A new synthetic approach and in vitro antimicrobial evaluation of novel imidazole incorporated 4-thiazolidinone motifs

N.C. Desai; V.V. Joshi; K.M. Rajpara; Atul H. Makwana

doi:10.1016/j.arabjc.2012.10.020

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Original article

10 (

1_suppl

); S589-S599

doi:

10.1016/j.arabjc.2012.10.020

A new synthetic approach and in vitro antimicrobial evaluation of novel imidazole incorporated 4-thiazolidinone motifs

N.C. Desai^⁎, V.V. Joshi, K.M. Rajpara, Atul H. Makwana

Division of Medicinal Chemistry, Department of Chemistry, Mahatma Gandhi Campus, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364 002, Gujarat, India

⁎Corresponding author. Tel./fax: +91 278 2439852. dnisheeth@rediffmail.com (N.C. Desai)

Received: 2012-4-11, Accepted: 2012-10-23, Published: 2012-02-01

Disclaimer:
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.

Peer review under responsibility of King Saud University.

Abstract

It is our ongoing effort to search new bio-active molecules and as a part of this, several chemical processes like condensation, cycloaddition were carried out to furnish 2-((1-(4-(4-(arylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazono)thiazolidin-4-ones (4a–o). All compounds were characterized by IR, ¹H NMR, ¹³C NMR and mass spectra. Newly synthesized compounds were screened for their antibacterial and antifungal activities on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus pyogenes, Candida albicans, Aspergillus niger and Aspergillus clavatus by bioassay namely serial broth dilution. On the basis of statistical analysis, it was observed that these compounds showed significant co-relation. The synthesized compounds showed potent antimicrobial activity against test microorganisms.

Keywords

Imidazole

4-Thiazolidinone

Antibacterial activity

Antifungal activity

MIC

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1 Introduction

Recently, antibiotic-resistant microbes are making their inexorable march and medicinal chemists have now realized that the discovery of more powerful antibiotics is not the only answer to this threat. But, a real need exists in searching a novel antimicrobial that expresses antimicrobial properties, possibly acting through mechanisms different from those of existing drugs. In this context, it is very essential to successfully develop novel, efficient bio-active molecules with clinically unexploited mode of action (Rubinstein, 1994; Brumfitt and Hamilton-Miller, 1994; Neu, 1992; Barry et al., 2000 ).

The pharmacological interest of the imidazole ring has been established, nitroimidazoles being extensively used in therapy against amoebic, trichomonal, giardial and anaerobic infections or as hypoxic cell radiosensitizers (Nair and Nagarajan, 1983). Metronidazole and substituted imidazoles are well-tolerated drugs that are potentially active against leishmania, but their use in the treatment of cutaneous and visceral leishmaniasis has produced conflicting results (Gangneux et al., 1999). Clotrimazole is an antifungal medication commonly used in the treatment of fungal infections such as vaginal yeast infections, oral thrush and ringworm. The imidazole moiety which incorporates both p-excessive and p-deficient characteristics has proven to be a master key in the range of drug target families (Abdel-Meguid et al., 1994; Muller, 2003). Compounds incorporating the imidazole scaffold are known as inhibitors of p38 MAPK (Laufer et al., 2004), JNK (Lisnock et al., 2002), B-Raf kinase (Takle et al., 2006), transforming growth factor β-1 (TGF-β1) type 1 receptor kinase (Laping et al., 2002) and acyl-CoA: cholesterol O-acyl transferase (ACAT) (Riddell et al., 1996). Imidazoles substituted with 2-arylamino functionality have been reported to have potent and selective agonist activity at α₂-adrenoceptors (Munk et al., 1997). Further the chemistry of thiazolidinone ring system is of considerable interest as it is a core structure in various synthetic pharmaceuticals displaying a broad spectrum of biological activities (Desai et al., 2012a). The thiazolidinone nucleus also appears frequently in the structure of various natural products, notably thiamine, compounds possessing cardiac and glycemic benefits such as troglitazone (Ghazzi et al., 1997) and many metabolic products of fungi and primitive marine animals, including 2-(aminoalkyl)-thiazole-4-carboxylic acids (Ulrich et al., 1987). Numerous thiazolidinone derivatives have shown significant bioactivities such as antidiarrhoeal (Diurno et al., 1997), anticonvulsant (Ragab et al., 1997), antimicrobial (Sattigeri et al., 2005), antidiabetic (Norisada et al., 2004), antihistaminic (Previtera et al., 1994), anticancer (Havrylyuk et al., 2009), anti HIV (Rawal et al., 2005), Ca²⁺ channel blocker (Kato et al., 1999b), PAF antagonist (Tanabe et al., 1991), cardioprotective (Kato et al., 1999a), antiischemic (Adachi et al., 1999), COX inhibitory (Ottana et al., 2002), anti-platelet activating factor (Tanabe et al., 1995), non-peptide thrombin receptor antagonist (Kato et al., 1999), tumor necrosis factor-α antagonist (Voss et al., 2003) and nematicidal activities. Certain commercially available drugs containing imidazole and 4-thiazolidinone nucleus are shown in Fig. 1.

Commercially available drugs containing imidazoline and thiazolidinone nucleus.

It must be emphasized, that a combination of imidazole template with 4-thiazolidinone is a well-known approach for a drug-like molecule’s build-up, which allows achieving new pharmacological profile, action strengthening or toxicity lowering. As part of our ongoing research in developing of new bio-active molecules (Desai et al., 2011, 2012b,c,d,e,f ), we tried to study the influence of imidazole and 4-thiazolidinone scaffold combination on the antimicrobial effect. The structural variations were explored by substituting the imidazoline moiety in position four and by introduction of different arylidene substituents. The latter were recently exploited as bioactive arms on heterocyclic scaffolds useful to pharmacological effect realization of 4-thiazolidinone based compounds.

2 Experimental

2.1

2.1 General

All reactions except those in aqueous media were carried out by standard techniques for the exclusion of moisture. Melting points were determined on an electro thermal melting point apparatus and were reported uncorrected. TLC on silica gel plates (Merck, 60, F₂₅₄) was used for purity checking and reaction monitoring. Column chromatography on silica gel (Merck, 70–230 mesh and 230–400 mesh ASTH for flash chromatography) was applied when necessary to isolate and purify the reaction products. Elemental analysis (% C, H, N) was carried out by a Perkin-Elmer 2400 CHN analyzer. IR spectra of all compounds were recorded on a Perkin-Elmer FT-IR spectrophotometer in KBr. ¹H NMR spectra were recorded on Varian Gemini 300 MHz and ¹³C NMR spectra on Varian Mercury-400, 100 MHz in DMSO-d₆ as a solvent and tetramethylsilane (TMS) as an internal standard. Mass spectra were scanned on a Shimadzu LCMS 2010 spectrometer. Anhydrous reactions were carried out in oven-dried glassware in a nitrogen atmosphere.

2.2

2.2 General procedure for preparation 1-(4-acetylphenyl)-4-(arylidene)-2-phenyl-1H-imidazol-5(4H)-ones (2a-o)

Compounds 1-(4-acetylphenyl)-4-(arylidene)-2-phenyl-1H-imidazol-5(4H)-ones (2a–o) were prepared according to the literature method (Badr and Mahgoub, 1989).

2.3

2.3 General procedure for preparation 2-(1-(4-(4-(arylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazinecarbothioamides (3a-o)

A mixture of compounds 1-(4-acetylphenyl)-4-(arylidene)-2-phenyl-1H-imidazol-5(4H)-ones (2a–o) (0.01 mol) and thiosemicarbazide (0.01 mol) in ethanol (40 mL) was heated under reflux for 1 h. The separated solid was recrystallized by ethanol to give compounds (3a–o).

2.3.1

2.3.1 2-(1-(4-(4-Benzylidene-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazine carbothioamide (3a)

Yield: 67%; m.p.: 182–184 °C; IR (KBr) ν_max/cm⁻¹: 3442, 3370 (NH₂), 3237 (NH), 3064 (C–H, aromatic), 2921, 3002 (C–H), 1684 (C⚌O), 1579 (C⚌N), 1513 (C⚌C), 1330 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.30 (s, 3H, CH₃), 6.43 (brs, 2H, D₂O exch., NH₂), 6.97 (t, J = 8.4 Hz, 1H, Ar–H), 7.12 (t, J = 8.4 Hz, 2H, Ar–H), 7.30 (d, J = 7.4 Hz, 2H, Ar–H), 7.39 (s, 1H, CH⚌C), 7.48 (d, J = 7.2 Hz, 2H, Ar–H), 7.54 (t, J = 8.1 Hz, 2H, Ar–H), 7.59 (t, J = 8.0 Hz, 1H, Ar–H), 7.94 (d, J = 8.0 Hz, 2H, Ar–H), 8.02 (d, J = 7.6 Hz, 2H, Ar–H), 8.70 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.3, 114.6, 124.3, 127.4, 128.2, 128.3, 128.7, 128.8, 129.4, 130.1, 131.4, 132.8, 135.2, 136.4, 141.3, 147.3, 158.3, 170.6, 179.4; LCMS (m/z): 439 (M⁺); Anal. Calcd. For C₂₅H₂₁N₅OS: C-68.32, H-4.82, N-15.93; Found: C-68.39, H-4.99, N-15.82%.

2.3.2

2.3.2 2-(1-(4-(4-(2-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3b)

Yield: 63%; m.p.: 193–195 °C; IR (KBr) ν_max/cm⁻¹: 3432, 3363 (NH₂), 3238 (NH), 3054 (C–H, aromatic), 2928, 3012 (C–H), 1681 (C⚌O), 1572 (C⚌N), 1522 (C⚌C), 1335 (C⚌S), 720 (C–Cl stretching); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.34 (s, 3H, CH₃), 6.44 (brs, 2H, D₂O exch., NH₂), 7.17 (t, J = 8.0 Hz, 1H, Ar–H), 7.21 (t, J = 7.4 Hz, 1H, Ar–H), 7.34 (d, J = 8.4 Hz, 1H, Ar–H), 7.42 (d, J = 8.4 Hz, 1H, Ar–H), 7.49 (d, J = 7.2 Hz, 2H, Ar–H), 7.56 (t, J = 8.0 Hz, 2H, Ar–H), 7.61 (t, J = 8.6 Hz, 1H, Ar–H), 7.70 (s, 1H, CH⚌C), 7.97 (d, J = 7.6 Hz, 2H, Ar–H), 8.05 (d, J = 7.4 Hz, 2H, Ar–H), 8.74 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.3, 110.8, 124.3, 127.8, 128.2, 128.7, 128.8, 129.1, 129.4, 129.9, 130.1, 131.4, 132.5, 132.8, 134.5, 135.2, 141.3, 147.3, 158.3, 170.6, 179.4; LCMS (m/z): 473 (M⁺); Anal. Calcd. For C₂₅H₂₀ClN₅OS: C-63.35, H-4.25, N-14.78; Found: C-63.42, H-4.19, N-14.85%.

2.3.3

2.3.3 2-(1-(4-(4-(4-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3c)

Yield: 66%; m.p.: 187–189 °C; IR (KBr) ν_max/cm⁻¹: 3422, 3355 (NH₂), 3252 (NH), 3062 (C–H, aromatic), 2924, 3003 (C–H), 1687 (C⚌O), 1580 (C⚌N), 1527 (C⚌C), 1331 (C⚌S), 735 (C–Cl stretching); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.37 (s, 3H, CH₃), 6.47 (brs, 2H, D₂O exch., NH₂), 7.36 (s, 1H, CH⚌C), 7.40 (d, J = 8.0 Hz, 2H, Ar–H), 7.46 (d, J = 7.4 Hz, 2H, Ar–H), 7.54 (t, J = 8.2 Hz, 2H, Ar–H), 7.63 (t, J = 8.0 Hz, 1H, Ar–H), 7.68 (t, J = 8.4 Hz, 2H, Ar–H), 7.94 (d, J = 8.2 Hz, 2H, Ar–H), 8.01 (d, J = 7.4 Hz, 2H, Ar–H), 8.78 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.1, 114.4, 124.5, 128.2, 128.5, 128.7, 129.0, 129.5, 130.6, 131.3, 133.1, 133.3, 134.7, 135.8, 141.8, 147.3, 158.5, 170.7, 179.2; LCMS (m/z): 473 (M⁺); Anal. Calcd. For C₂₅H₂₀ClN₅OS: C-63.35, H-4.25, N-14.78; Found: C-63.29, H-4.18, N-14.84%.

2.3.4

2.3.4 2-(1-(4-(4-(2-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3d)

Yield: 62%; m.p.: 176–178 °C; IR (KBr) ν_max/cm⁻¹: 3417, 3366 (NH₂), 3243 (NH), 3052 (C–H, aromatic), 2917, 3006 (C–H), 1691 (C⚌O), 1574 (C⚌N), 1533 (C⚌C), 1328 (C⚌S), 1151 (C–F stretching); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.34 (s, 3H, CH₃), 6.44 (brs, 2H, D₂O exch., NH₂), 7.15 (t, J = 8.4 Hz, 1H, Ar–H), 7.22 (d, J = 7.8 Hz, 1H, Ar–H), 7.39 (d, J = 8.2 Hz, 1H, Ar–H), 7.45 (d, J = 7.4 Hz, 2H, Ar–H), 7.58 (t, J = 8.6 Hz, 2H, Ar–H), 7.64 (t, J = 9.0 Hz, 1H, Ar–H), 7.69 (d, J = 8.4 Hz, 1H, Ar–H), 7.92 (d, J = 8.0 Hz, 2H, Ar–H), 8.08 (d, J = 7.2 Hz, 2H, Ar–H), 7.69 (s, 1H, CH⚌C), 8.79 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.6, 110.6, 115.3, 123.1, 124.5, 124.8, 128.2, 128.6, 128.8, 129.2, 129.6, 130.5, 131.7, 132.3, 135.6, 141.3, 147.5, 158.3, 161.3, 170.2, 179.1; LCMS (m/z): 457 (M⁺); Anal. Calcd. For C₂₅H₂₀FN₅OS: C-65.63, H-4.41, N-15.31; Found: C-65.67, H-4.35, N-15.39%.

2.3.5

2.3.5 2-(1-(4-(4-(4-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3e)

Yield: 66%; m.p.: 195–197 °C; IR (KBr) ν_max/cm⁻¹: 3412, 3354 (NH₂), 3251 (NH), 3077 (C–H, aromatic), 2922, 3004 (C–H), 1682 (C⚌O), 1570 (C⚌N), 1526 (C⚌C), 1333 (C⚌S), 1145 (C–F stretching); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.33 (s, 3H, CH₃), 6.48 (brs, 2H, D₂O exch., NH₂), 7.20 (d, J = 7.4 Hz, 2H, Ar–H), 7.39 (s, 1H, CH⚌C), 7.43 (d, J = 8.2 Hz, 2H, Ar–H), 7.58 (t, J = 8.6 Hz, 2H, Ar–H), 7.67 (t, J = 8.0 Hz, 1H, Ar–H), 7.75 (d, J = 7.4 Hz, 2H, Ar–H), 7.93 (d, J = 8.0 Hz, 2H, Ar–H), 8.02 (d, J = 7.6 Hz, 2H, Ar–H), 8.76 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.1, 114.3, 115.3, 124.6, 128.2, 128.5, 129.7, 130.1, 130.3, 131.3, 131.6, 132.3, 135.6, 141.4, 147.1, 158.5, 162.4, 170.7, 179.2; LCMS (m/z): 457 (M⁺); Anal. Calcd. For C₂₅H₂₀FN₅OS: C-65.63, H-4.41, N-15.31; Found: C-65.70, H-4.48, N-15.25%.

2.3.6

2.3.6 2-(1-(4-(4-(2-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3f)

Yield: 69%; m.p.: 178–180 °C; IR (KBr) ν_max/cm⁻¹: 3417, 3340 (NH₂), 3264 (NH), 3065 (C–H, aromatic), 2927, 3008 (C–H), 1689 (C⚌O), 1577 (C⚌N), 1517 (C⚌C), 1483, 1355 (NO₂), 1325 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.39 (s, 3H, CH₃), 6.52 (brs, 2H, D₂O exch., NH₂), 7.48 (d, J = 8.2 Hz, 2H, Ar–H), 7.54 (t, J = 8.6 Hz, 2H, Ar–H), 7.68 (t, J = 8.2 Hz, 1H, Ar–H), 7.74 (t, J = 7.4 Hz, 1H, Ar–H), 7.83 (t, J = 8.4 Hz, 1H, Ar–H), 7.89 (d, J = 7.4 Hz, 1H, Ar–H), 7.95 (s, 1H, CH⚌C), 7.99 (d, J = 8.4 Hz, 2H, Ar–H), 8.04 (d, J = 7.6 Hz, 2H, Ar–H), 8.23 (d, J = 8.0 Hz, 1H, Ar–H), 8.76 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.4, 110.7, 123.4, 124.1, 127.2, 128.1, 128.4, 128.7, 128.8, 129.2, 130.4, 131.3, 132.1, 134.4, 135.5, 141.3, 147.2, 147.4, 158.6, 170.8, 179.3; LCMS (m/z): 484 (M⁺); Anal. Calcd. For C₂₅H₂₀N₆O₃S: C-61.97, H-4.16, N-17.34; Found: C-61.90, H-4.22, N-17.29%.

2.3.7

2.3.7 2-(1-(4-(4-(4-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3g)

Yield: 66%; m.p.: 218–220 °C; IR (KBr) ν_max/cm⁻¹: 3423, 3338 (NH₂), 3272 (NH), 3058 (C–H, aromatic), 2932, 3014 (C–H), 1691 (C⚌O), 1581 (C⚌N), 1510 (C⚌C), 1487, 1352 (NO₂), 1330 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.36 (s, 3H, CH₃), 6.49 (brs, 2H, D₂O exch., NH₂), 7.44 (d, J = 7.2 Hz, 2H, Ar–H), 7.50 (s, 1H, CH⚌C), 7.59 (t, J = 8.6 Hz, 2H, Ar–H), 7.63 (t, J = 8.0 Hz, 1H, Ar–H), 7.99 (d, J = 8.4 Hz, 2H, Ar–H), 8.08 (d, J = 7.2 Hz, 2H, Ar–H), 8.10 (d, J = 8.4 Hz, 2H, Ar–H), 8.24 (d, J = 8.6 Hz, 2H, Ar–H), 8.79 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.6, 114.2, 123.8, 124.4, 128.5, 128.7, 129.2, 129.5, 130.7, 131.4, 132.2, 135.5, 141.3, 141.8, 147.2, 147.5, 158.9, 170.4, 179.8; LCMS (m/z): 484 (M⁺); Anal. Calcd. For C₂₅H₂₀N₆O₃S: C-61.97, H-4.16, N-17.34; Found: C-61.96, H-4.10, N-17.40%.

2.3.8

2.3.8 2-(1-(4-(4-(2-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3h)

Yield: 61%; m.p.: 187–189 °C; IR (KBr) ν_max/cm⁻¹: 3422 (OH), 3417, 3357 (NH₂), 3259 (NH), 3064 (C–H, aromatic), 2928, 3010 (C–H), 1683 (C⚌O), 1576 (C⚌N), 1515 (C⚌C), 1334 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.31 (s, 3H, CH₃), 6.42 (brs, 2H, D₂O exch., NH₂), 6.70 (d, J = 8.0 Hz, 1H, Ar–H), 6.94 (t, J = 8.2 Hz, 1H, Ar–H), 7.12 (t, J = 7.6 Hz, 1H, Ar–H), 7.49 (d, J = 7.4 Hz, 2H, Ar–H), 7.56 (t, J = 8.2 Hz, 2H, Ar–H), 7.61 (t, J = 8.4 Hz, 1H, Ar–H), 7.64 (d, J = 9.2 Hz, 1H, Ar–H), 7.71 (s, 1H, CH⚌C), 7.97 (t, J = 8.2 Hz, 2H, Ar–H), 8.03 (t, J = 7.4 Hz, 2H, Ar–H), 8.72 (s, 1H, D₂O exch., NH), 9.12 (s, 1H, D₂O exch., OH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.1, 110.5, 116.4, 117.1, 121.4, 124.6, 128.3, 128.5, 128.8, 129.2, 129.7, 130.3, 131.7, 132.1, 135.4, 141.7, 147.2, 157.3, 158.4, 170.3, 179.4; LCMS (m/z): 455 (M⁺); Anal. Calcd. For C₂₅H₂₁N₅O₂S: C-65.92, H-4.65, N-15.37; Found: C-65.86, H-4.72, N-15.42%.

2.3.9

2.3.9 2-(1-(4-(4-(3-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3i)

Yield: 64%; m.p.: 167–169 °C; IR (KBr) ν_max/cm⁻¹: 3428 (OH), 3416, 3364 (NH₂), 3252 (NH), 3072 (C–H, aromatic), 2922, 3007 (C–H), 1687 (C⚌O), 1583 (C⚌N), 1520 (C⚌C), 1339 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.88 (s, 3H, CH₃), 3.93 (s, 2H, CH₂), 6.69 (s, 1H, Ar–H), 6.82 (d, J = 9.2 Hz, 1H, Ar–H), 7.14 (d, J = 8.4 Hz, 1H, Ar–H), 7.38 (s, 1H, CH⚌C), 7.46 (d, J = 8.2 Hz, 2H, Ar–H), 7.52 (t, J = 8.2 Hz, 2H, Ar–H), 7.67 (t, J = 8.4 Hz, 1H, Ar–H), 7.58 (t, J = 8.6 Hz, 1H, Ar–H), 7.95 (t, J = 8.2 Hz, 2H, Ar–H), 8.03 (t, J = 7.4 Hz, 2H, Ar–H), 8.55 (s, 1H, D₂O exch., NH), 9.11 (s, 1H, D₂O exch., OH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.5, 112.2, 114.4, 115.7, 121.7, 124.6, 128.1, 128.5, 129.5, 130.2, 130.6, 131.5, 132.4, 135.5, 139.8, 141.7, 147.2, 158.6, 158.9, 170.2, 179.7; LCMS (m/z): 455 (M⁺); Anal. Calcd. For C₂₅H₂₁N₅O₂S: C-65.92, H-4.65, N-15.37; Found: C-65.97, H-4.58, N-15.32%.

2.3.10

2.3.10 2-(1-(4-(4-(4-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3j)

Yield: 66%; m.p.: 198–200 °C; IR (KBr) ν_max/cm⁻¹: 3421 (OH), 3413, 3356 (NH₂), 3263 (NH), 3083 (C–H, aromatic), 2929, 3013 (C–H), 1684 (C⚌O), 1580 (C⚌N), 1517 (C⚌C), 1333 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.33 (s, 3H, CH₃), 6.42 (brs, 2H, D₂O exch., NH₂), 6.63 (d, J = 7.2 Hz, 2H, Ar–H), 7.34 (s, 1H, CH⚌C), 7.42 (d, J = 8.4 Hz, 2H, Ar–H), 7.56 (t, J = 8.6 Hz, 2H, Ar–H), 7.59 (d, J = 8.2 Hz, 2H, Ar–H), 7.65 (t, J = 8.6 Hz, 1H, Ar–H), 7.91 (d, J = 8.2 Hz, 2H, Ar–H), 8.04 (d, J = 7.2 Hz, 2H, Ar–H), 8.75 (s, 1H, D₂O exch., NH), 9.15 (s, 1H, D₂O exch., OH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.5, 114.7, 115.4, 124.2, 127.4, 128.3, 128.8, 129.5, 130.3, 131.2, 131.6, 132.9, 135.1, 141.5, 147.2, 157.4, 158.6, 170.2, 179.7; LCMS (m/z): 455 (M⁺); Anal. Calcd. For C₂₅H₂₁N₅O₂S: C-65.92, H-4.65, N-15.37; Found: C-65.88, H-4.71, N-15.44%.

2.3.11

2.3.11 2-(1-(4-(4-(2-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3k)

Yield: 61%; m.p.: 187–189 °C; IR (KBr) ν_max/cm⁻¹: 3418, 3354 (NH₂), 3261 (NH), 3075 (C–H, aromatic), 2924, 3003 (C–H), 1688 (C⚌O), 1575 (C⚌N), 1512 (C⚌C), 1337 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.27 (s, 3H, CH₃), 2.45 (s, 3H, CH₃), 6.40 (brs, 2H, D₂O exch., NH₂), 7.01 (d, J = 9.0 Hz, 1H, Ar–H), 7.21 (t, J = 8.6 Hz, 1H, Ar–H), 7.29 (t, J = 7.6 Hz, 1H, Ar–H), 7.38 (d, J = 8.4 Hz, 1H, Ar–H), 7.44 (d, J = 8.2 Hz, 2H, Ar–H), 7.53 (t, J = 8.0 Hz, 2H, Ar–H), 7.64 (t, J = 8.6 Hz, 1H, Ar–H), 7.73 (s, 1H, CH⚌C), 7.95 (t, J = 8.2 Hz, 2H, Ar–H), 8.01 (t, J = 7.6 Hz, 2H, Ar–H), 8.69 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.5, 19.1, 110.2, 124.5, 125.4, 127.4, 127.8, 128.2, 128.4, 128.8, 129.1, 130.4, 131.5, 132.3, 135.7, 136.1, 136.6, 141.4, 147.2, 158.5, 170.4, 179.1; LCMS (m/z): 453 (M⁺); Anal. Calcd. For C₂₆H₂₃N₅OS: C-68.85, H-5.11, N-15.44; Found: C-68.91, H-5.06, N-15.52%.

2.3.12

2.3.12 2-(1-(4-(4-(3-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3l)

Yield: 67%; m.p.: 203–205 °C; IR (KBr) ν_max/cm⁻¹: 3412, 3338 (NH₂), 3248 (NH), 3066 (C–H, aromatic), 2937, 3011 (C–H), 1681 (C⚌O), 1572 (C⚌N), 1518 (C⚌C), 1330 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.32 (s, 3H, CH₃), 2.38 (s, 3H, CH₃), 6.41 (brs, 2H, D₂O exch., NH₂), 7.07 (s, 1H, Ar–H), 7.10 (d, J = 8.6 Hz, 1H, Ar–H), 7.19 (t, J = 7.2 Hz, 1H, Ar–H), 7.35 (s, 1H, CH⚌C), 7.40 (d, J = 7.6 Hz, 2H, Ar–H), 7.46 (d, J = 8.4 Hz, 1H, Ar–H), 7.53 (t, J = 8.6 Hz, 2H, Ar–H), 7.61 (t, J = 8.2 Hz, 1H, Ar–H), 7.93 (t, J = 8.6 Hz, 2H, Ar–H), 8.11 (t, J = 7.4 Hz, 2H, Ar–H), 8.70 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.6, 21.6, 114.5, 124.1, 125.6, 126.6, 128.4, 128.5, 128.7, 128.9, 129.6, 130.3, 131.2, 132.7, 135.1, 135.7, 138.3, 141.6, 147.3, 158.6, 170.2, 179.8; LCMS (m/z): 453 (M⁺); Anal. Calcd. For C₂₆H₂₃N₅OS: C-68.85, H-5.11, N-15.44; Found: C-68.89, H-5.17, N-15.39%.

2.3.13

2.3.13 2-(1-(4-(4-(4-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3m)

Yield: 62%; m.p.: 192–194 °C; IR (KBr) ν_max/cm⁻¹: 3410, 3345 (NH₂), 3239 (NH), 3060 (C–H, aromatic), 2931, 3009 (C–H), 1687 (C⚌O), 1579 (C⚌N), 1525 (C⚌C), 1335 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.28 (s, 3H, CH₃), 2.34 (s, 3H, CH₃), 6.37 (brs, 2H, D₂O exch., NH₂), 7.16 (d, J = 8.0 Hz, 2H, Ar–H), 7.33 (s, 1H, CH⚌C), 7.47 (d, J = 8.2 Hz, 2H, Ar–H), 7.53 (t, J = 7.8 Hz, 2H, Ar–H), 7.62 (d, J = 8.6 Hz, 2H, Ar–H), 7.69 (t, J = 8.6 Hz, 1H, Ar–H), 7.96 (d, J = 7.6 Hz, 2H, Ar–H), 8.07 (d, J = 8.4 Hz, 2H, Ar–H), 8.79 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.5, 21.1, 114.2, 124.6, 128.2, 128.3, 128.7, 128.8, 129.6, 130.4, 131.6, 132.4, 132.8, 135.2, 137.7, 141.1, 147.5, 158.2, 170.1, 179.5; LCMS (m/z): 453 (M⁺); Anal. Calcd. For C₂₆H₂₃N₅OS: C-68.85, H-5.11, N-15.44; Found: C-68.80, H-5.03, N-15.50%.

2.3.14

2.3.14 2-(1-(4-(4-(2-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3n)

Yield: 68%; m.p.: 168–170 °C; IR (KBr) ν_max/cm⁻¹: 3417, 3349 (NH₂), 3238 (NH), 3058 (C–H, aromatic), 2927, 3009 (C–H), 1683 (C⚌O), 1581 (C⚌N), 1522 (C⚌C), 1329 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.36 (s, 3H, CH₃), 3.74 (s, 3H, CH₃), 6.45 (brs, 2H, D₂O exch., NH₂), 6.89 (d, J = 7.2 Hz, 1H, Ar–H), 6.94 (t, J = 8.4 Hz, 1H, Ar–H), 7.25 (t, J = 8.2 Hz, 1H, Ar–H), 7.47 (d, J = 8.6 Hz, 2H, Ar–H), 7.51 (t, J = 8.4 Hz, 2H, Ar–H), 7.61 (t, J = 8.8 Hz, 1H, Ar–H), 7.68 (d, J = 7.6 Hz, 1H, Ar–H), 7.72 (s, 1H, CH⚌C), 7.93 (t, J = 8.0 Hz, 2H, Ar–H), 8.04 (t, J = 7.6 Hz, 2H, Ar–H), 8.65 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.1, 54.8, 110.3, 114.4, 114.7, 121.3, 124.2, 128.5, 128.6, 128.7, 128.9, 129.1, 130.4, 131.5, 132.3, 135.5, 141.3, 147.3, 158.3, 159.4, 170.6, 179.4; LCMS (m/z): 469 (M⁺); Anal. Calcd. For C₂₆H₂₃N₅O₂S: C-66.50, H-4.94, N-14.91; Found: C-66.57, H-4.87, N-14.96%.

2.3.15

2.3.15 2-(1-(4-(4-(4-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3o)

Yield: 65%; m.p.: 184–196 °C; IR (KBr) ν_max/cm⁻¹: 3414, 3342 (NH₂), 3239 (NH), 3061 (C–H, aromatic), 2925, 3005 (C–H), 1689 (C⚌O), 1586 (C⚌N), 1525 (C⚌C), 1332 (C⚌S); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.28 (s, 3H, CH₃), 3.75 (s, 3H, OCH₃), 6.37 (brs, 2H, D₂O exch., NH₂), 6.92 (d, J = 7.8 Hz, 2H, Ar–H), 7.37 (s, 1H, CH⚌C), 7.43 (d, J = 7.6 Hz, 2H, Ar–H), 7.52 (t, J = 8.6 Hz, 2H, Ar–H), 7.62 (t, J = 8.4 Hz, 1H, Ar–H), 7.68 (d, J = 8.4 Hz, 2H, Ar–H), 7.92 (d, J = 8.2 Hz, 2H, Ar–H), 8.03 (d, J = 8.6 Hz, 2H, Ar–H), 8.74 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 18.3, 54.2, 114.3, 114.6, 124.3, 127.3, 128.2, 128.7, 129.4, 130.1, 130.5, 131.4, 132.8, 135.2, 141.3, 147.3, 158.3, 159.2, 170.6, 179.4; LCMS (m/z): 469 (M⁺); Anal. Calcd. For C₂₆H₂₃N₅O₂S: C-66.50, H-4.94, N-14.91; Found: C-66.43, H-4.99, N-14.84%.

2.4

2.4 General procedure for preparation 2-((1-(4-(4-(arylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl) ethylidene)hydrazono)thiazolidin-4-ones (4a-o)

A mixture of compounds 2-(1-(4-(4-(arylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3a–o) (0.01 mol), ethyl bromoacetate (0.01 mol) and sodium acetate (0.08 mol) in ethanol (40 mL) was heated under reflux for 1 h. The separated solid was recrystallized from ethanol.

2.4.1

2.4.1 2-((1-(4-(4-Benzylidene-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazono) thiazolidin-4-one (4a)

Yield: 60%; m.p.: 188–190 °C; IR (KBr) ν_max/cm⁻¹: 3353 (NH), 3054 (C–H, aromatic), 2921, 2863 (C–H), 1688, 1708 (C⚌O), 1584 (C⚌N), 1508 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.89 (s, 3H, CH₃), 3.92 (s, 2H, CH₂), 6.94 (t, J = 8.4 Hz, 1H, Ar–H), 7.15 (t, J = 8.4 Hz, 2H, Ar–H), 7.31 (d, J = 7.4 Hz, 2H, Ar–H), 7.46 (d, J = 7.2 Hz, 2H, Ar–H), 7.55 (t, J = 8.1 Hz, 2H, Ar–H), 7.58 (t, J = 8.0 Hz, 1H, Ar–H), 7.83 (s, 1H, CH = C), 7.91 (d, J = 8.0 Hz, 2H, Ar–H), 8.04 (d, J = 7.6 Hz, 2H, Ar–H), 8.51 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.3, 39.5, 114.2, 124.3, 127.3, 127.5, 128.2, 128.3, 128.7, 128.8, 129.4, 130.1, 131.4, 135.2, 136.4, 141.2, 142.1, 158.3, 160.4, 170.3, 176.2; LCMS (m/z): 479 (M⁺); Anal. Calcd. For C₂₇H₂₁N₅O₂S: C-67.62, H-4.41, N-14.60; Found: C-67.68, H-4.35, N-14.53%.

2.4.2

2.4.2 2-((1-(4-(4-(2-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4b)

Yield: 54%; m.p.: 174–176 °C; IR (KBr) ν_max/cm⁻¹: 3349 (NH), 3059 (C–H, aromatic), 2929, 2867 (C–H), 1693, 1703 (C⚌O), 1587 (C⚌N), 1512 (C⚌C), 743 (C–Cl); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.84 (s, 3H, CH₃), 3.92 (s, 2H, CH₂), 7.16 (t, J = 8.0 Hz, 1H, Ar–H), 7.23 (t, J = 7.4 Hz, 1H, Ar–H), 7.34 (d, J = 8.4 Hz, 1H, Ar–H), 7.44 (d, J = 8.4 Hz, 1H, Ar–H), 7.49 (d, J = 7.2 Hz, 2H, Ar–H), 7.57 (t, J = 8.0 Hz, 2H, Ar–H), 7.64 (t, J = 8.6 Hz, 1H, Ar–H), 7.97 (d, J = 7.6 Hz, 2H, Ar–H), 8.05 (d, J = 7.4 Hz, 2H, Ar–H), 8.11 (s, 1H, CH⚌C), 8.53 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.5, 39.7, 110.3, 124.4, 127.6, 127.8, 128.2, 128.6, 128.7, 129.1, 129.3, 129.9, 130.6, 131.4, 132.8, 134.3, 135.5, 141.8, 142.3, 158.6, 160.3, 170.6, 176.5; LCMS (m/z): 513 (M⁺); Anal. Calcd. For C₂₇H₂₀ClN₅O₂S: C-63.09, H-3.92, N-13.63; Found: C-63.17, H-3.86, N-13.70%.

2.4.3

2.4.3 2-((1-(4-(4-(4-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4c)

Yield: 64%; m.p.: 232–234 °C; IR (KBr) ν_max/cm⁻¹: 3360 (NH), 3064 (C–H, aromatic), 2922, 2872 (C–H), 1687, 1710 (C⚌O), 1584 (C⚌N), 1506 (C⚌C), 757 (C–Cl); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.86 (s, 3H, CH₃), 3.94 (s, 2H, CH₂), 7.42 (d, J = 8.0 Hz, 2H, Ar–H), 7.48 (d, J = 7.4 Hz, 2H, Ar–H), 7.53 (t, J = 8.2 Hz, 2H, Ar–H), 7.63 (t, J = 8.0 Hz, 1H, Ar–H), 7.68 (t, J = 8.4 Hz, 2H, Ar–H), 7.82 (s, 1H, CH⚌C), 7.93 (d, J = 8.2 Hz, 2H, Ar–H), 8.02 (d, J = 7.4 Hz, 2H, Ar–H), 8.57 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.4, 39.6, 114.1, 124.6, 127.3, 128.5, 128.7, 128.9, 129.0, 129.2, 130.5, 131.6, 133.1, 134.7, 135.6, 141.4, 142.6, 158.3, 160.6, 170.5, 176.5; LCMS (m/z): 513 (M⁺); Anal. Calcd. For C₂₇H₂₀ClN₅O₂S: C-63.09, H-3.92, N-13.63; Found: C-63.02, H-3.97, N-13.58%.

2.4.4

2.4.4 2-((1-(4-(4-(2-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4d)

Yield: 61%; m.p.: 199–201 °C; IR (KBr) ν_max/cm⁻¹: 3352 (NH), 3072 (C–H, aromatic), 2932, 2865 (C–H), 1685, 1703 (C⚌O), 1578 (C⚌N), 1514 (C⚌C), 1147 (C–F); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.92 (s, 3H, CH₃), 3.91 (s, 2H, CH₂), 7.18 (t, J = 8.4 Hz, 1H, Ar–H), 7.21 (d, J = 7.8 Hz, 1H, Ar–H), 7.37 (d, J = 8.2 Hz, 1H, Ar–H), 7.44 (d, J = 7.4 Hz, 2H, Ar–H), 7.56 (t, J = 8.6 Hz, 2H, Ar–H), 7.62 (t, J = 9.0 Hz, 1H, Ar–H), 7.68 (d, J = 8.4 Hz, 1H, Ar–H), 7.92 (d, J = 8.0 Hz, 2H, Ar–H), 8.04 (d, J = 7.2 Hz, 2H, Ar–H), 8.10 (s, 1H, CH⚌C), 8.52 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.5, 39.3, 110.8, 115.3, 123.1, 124.3, 124.7, 127.6, 128.3, 128.4, 128.7, 129.5, 129.6, 130.3, 131.8, 135.6, 141.4, 142.6, 158.3, 160.5, 161.2, 170.3, 176.7; LCMS (m/z): 497 (M⁺); Anal. Calcd. For C₂₇H₂₀FN₅O₂S: C-65.18, H-4.05, N-14.08; Found: C-65.11, H-4.11, N-14.17%.

2.4.5

2.4.5 2-((1-(4-(4-(4-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4e)

Yield: 56%; m.p.: 188–190 °C; IR (KBr) ν_max/cm⁻¹: 3349 (NH), 3068 (C–H, aromatic), 2929, 2864 (C–H), 1693, 1710 (C⚌O), 1584 (C⚌N), 1519 (C⚌C), 1154 (C–F); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.95 (s, 3H, CH₃), 3.97 (s, 2H, CH₂), 7.24 (d, J = 7.4 Hz, 2H, Ar–H), 7.41 (d, J = 8.2 Hz, 2H, Ar–H), 7.56 (t, J = 8.6 Hz, 2H, Ar–H), 7.62 (t, J = 8.0 Hz, 1H, Ar–H), 7.78 (d, J = 7.4 Hz, 2H, Ar–H), 7.83 (s, 1H, CH⚌C), 7.95 (d, J = 8.0 Hz, 2H, Ar–H), 8.05 (d, J = 7.6 Hz, 2H, Ar–H), 8.57 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.5, 39.2, 114.5, 115.5, 124.5, 127.4, 128.6, 128.9, 129.2, 130.5, 130.8, 131.4, 131.7, 135.5, 141.3, 142.6, 158.3, 160.5, 162.4, 170.4, 176.4; LCMS (m/z): 497 (M⁺); Anal. Calcd. For C₂₇H₂₀FN₅O₂S: C-65.18, H-4.05, N-14.08; Found: C-65.24, H-4.01, N-14.00%.

2.4.6

2.4.6 2-((1-(4-(4-(2-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4f)

Yield: 59%; m.p.: 213–215 °C; IR (KBr) ν_max/cm⁻¹: 3343 (NH), 3072 (C–H, aromatic), 2924, 2868 (C-–H), 1687, 1702 (C⚌O), 1587 (C⚌N), 1512 (C⚌C), 1483, 1358 (NO₂); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.92 (s, 3H, CH₃), 3.94 (s, 2H, CH₂), 7.46 (d, J = 8.2 Hz, 2H, Ar–H), 7.56 (t, J = 8.6 Hz, 2H, Ar–H), 7.64 (t, J = 8.2 Hz, 1H, Ar–H), 7.72 (t, J = 7.4 Hz, 1H, Ar–H), 7.82 (t, J = 8.4 Hz, 1H, Ar–H), 7.91 (d, J = 7.4 Hz, 1H, Ar–H), 7.96 (d, J = 8.4 Hz, 2H, Ar–H), 8.23 (d, J = 8.0 Hz, 1H, Ar–H), 8.02 (d, J = 7.6 Hz, 2H, Ar–H), 8.34 (s, 1H, CH⚌C), 8.64 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.7, 39.3, 110.9, 123.4, 124.6, 127.2, 127.6, 128.2, 128.3, 128.5, 128.8, 129.4, 130.6, 131.3, 134.4, 135.5, 141.7, 142.4, 147.4, 158.6, 160.7, 170.7, 176.6; LCMS (m/z): 524 (M⁺); Anal. Calcd. For C₂₇H₂₀N₆O₄S: C-61.82, H-3.84, N-16.02; Found: C-61.76, H-3.89, N-16.07%.

2.4.7

2.4.7 2-((1-(4-(4-(4-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4g)

Yield: 54%; m.p.: 187–189 °C; IR (KBr) ν_max/cm⁻¹: 3354 (NH), 3065 (C–H, aromatic), 2934, 2863 (C–H), 1684, 1708 (C⚌O), 1583 (C⚌N), 1517 (C⚌C), 1489, 1362 (NO₂); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.97 (s, 3H, CH₃), 3.94 (s, 2H, CH₂), 7.45 (d, J = 7.2 Hz, 2H, Ar–H), 7.58 (t, J = 8.6 Hz, 2H, Ar–H), 7.64 (t, J = 8.0 Hz, 1H, Ar–H), 7.92 (s, 1H, CH⚌C), 7.99 (d, J = 8.4 Hz, 2H, Ar–H), 8.03 (d, J = 7.2 Hz, 2H, Ar–H), 8.12 (d, J = 8.4 Hz, 2H, Ar–H), 8.28 (d, J = 8.6 Hz, 2H, Ar–H), 8.62 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.7, 39.2, 114.5, 123.8, 124.4, 127.7, 128.2, 128.8, 129.2, 129.4, 130.7, 131.4, 135.6, 141.1, 141.4, 142.5, 147.2, 158.1, 160.5, 170.3, 176.6; LCMS (m/z): 524 (M⁺); Anal. Calcd. For C₂₇H₂₀N₆O₄S: C-61.82, H-3.84, N-16.02; Found: C-61.86, H-3.77, N-16.10%.

2.4.8

2.4.8 2-((1-(4-(4-(2-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4h)

Yield: 64%; m.p.: 235–237 °C; IR (KBr) ν_max/cm⁻¹: 3417 (O–H), 3354 (NH), 3073 (C–H, aromatic), 2926, 2867 (C–H), 1689, 1702 (C⚌O), 1588 (C⚌N), 1512 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.90 (s, 3H, CH₃), 6.42 (s, 2H, CH₂), 6.71 (d, J = 8.0 Hz, 1H, Ar–H), 6.95 (t, J = 8.2 Hz, 1H, Ar–H), 7.11 (t, J = 7.6 Hz, 1H, Ar–H), 7.47 (d, J = 7.4 Hz, 2H, Ar–H), 7.55 (t, J = 8.2 Hz, 2H, Ar–H), 7.60 (t, J = 8.4 Hz, 1H, Ar–H), 7.66 (d, J = 9.2 Hz, 1H, Ar–H), 7.94 (t, J = 8.2 Hz, 2H, Ar–H), 8.02 (t, J = 7.4 Hz, 2H, Ar–H), 8.11 (s, 1H, CH⚌C), 8.53 (s, 1H, D₂O exch., NH), 9.11 (s, 1H, D₂O exch., OH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.2, 39.7, 110.3, 116.4, 117.3, 121.3, 124.6, 127.6, 128.1, 128.4, 128.6, 129.2, 129.6, 130.4, 131.6, 135.3, 141.6, 142.8, 157.3, 158.2, 160.7, 170.2, 176.6; LCMS (m/z): 495 (M⁺); Anal. Calcd. For C₂₇H₂₁N₅O₃S: C-65.44, H-4.27, N-14.13; Found: C-65.51, H-4.33, N-14.20%.

2.4.9

2.4.9 2-((1-(4-(4-(3-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4i)

Yield: 53%; m.p.: 175–177 °C; IR (KBr) ν_max/cm⁻¹: 3414 (O–H), 3358 (NH), 3065 (C–H, aromatic), 2922, 2872 (C–H), 1685, 1705 (C⚌O), 1584 (C⚌N), 1518 (C = C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.88 (s, 3H, CH₃), 3.93 (s, 2H, CH₂), 6.69 (s, 1H, Ar–H), 6.81 (d, J = 9.2 Hz, 1H, Ar–H), 7.15 (d, J = 8.4 Hz, 1H, Ar–H), 7.47 (d, J = 8.2 Hz, 2H, Ar–H), 7.52 (t, J = 8.2 Hz, 2H, Ar–H), 7.67 (t, J = 8.4 Hz, 1H, Ar–H), 7.58 (t, J = 8.6 Hz, 1H, Ar–H), 7.95 (t, J = 8.2 Hz, 2H, Ar–H), 8.03 (t, J = 7.4 Hz, 2H, Ar–H), 7.86 (s, 1H, CH⚌C), 8.52 (s, 1H, D₂O exch., NH), 9.10 (s, 1H, D₂O exch., OH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.2, 39.6, 112.4, 114.7, 115.4, 121.5, 124.7, 127.2, 128.1, 128.6, 129.2, 130.1, 130.5, 131.6, 135.1, 139.8, 141.6, 142.3, 158.6, 158.8, 160.3, 170.5, 176.4; LCMS (m/z): 495 (M⁺); Anal. Calcd. For C₂₇H₂₁N₅O₃S: C-65.44, H-4.27, N-14.13; Found: C-65.40, H-4.22, N-14.08%.

2.4.10

2.4.10 2-((1-(4-(4-(4-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4j)

Yield: 58%; m.p.: 165–167 °C; IR (KBr) ν_max/cm⁻¹: 3417 (O–H), 3354 (NH), 3073 (C–H, aromatic), 2926, 2867 (C–H), 1689, 1701 (C⚌O), 1588 (C⚌N), 1512 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.91 (s, 3H, CH₃), 3.90 (s, 2H, CH₂), 6.62 (d, J = 7.2 Hz, 2H, Ar–H), 7.43 (d, J = 8.4 Hz, 2H, Ar–H), 7.55 (t, J = 8.6 Hz, 2H, Ar–H), 7.57 (d, J = 8.2 Hz, 2H, Ar–H), 7.66 (t, J = 8.6 Hz, 1H, Ar–H), 7.82 (s, 1H, CH⚌C), 7.91 (d, J = 8.2 Hz, 2H, Ar–H), 8.04 (d, J = 7.2 Hz, 2H, Ar–H), 8.53 (s, 1H, D₂O exch., NH), 9.15 (s, 1H, D₂O exch., OH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.1, 39.3, 114.5, 115.5, 124.5, 127.1, 127.8, 128.5, 128.2, 129.6, 130.5, 131.2, 131.5, 135.6, 141.6, 142.3, 157.8, 158.6, 160.2, 170.7, 176.3; LCMS (m/z): 495 (M⁺); Anal. Calcd. For C₂₇H₂₁N₅O₃S: C-65.44, H-4.27, N-14.13; Found: C-65.49, H-4.32, N-14.22%.

2.4.11

2.4.11 2-((1-(4-(4-(2-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4k)

Yield: 65%; m.p.: 205–207 °C; IR (KBr) ν_max/cm⁻¹: 3348 (NH), 3068 (C–H, aromatic), 2927, 2874 (C–H), 1681, 1706 (C⚌O), 1581 (C⚌N), 1516 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.45 (s, 3H, CH₃), 2.94 (s, 3H, CH₃), 3.91 (s, 2H, CH₂), 7.00 (d, J = 9.0 Hz, 1H, Ar–H), 7.21 (t, J = 8.6 Hz, 1H, Ar–H), 7.27 (t, J = 7.6 Hz, 1H, Ar–H), 7.38 (d, J = 8.4 Hz, 1H, Ar–H), 7.42 (d, J = 8.2 Hz, 2H, Ar–H), 7.55 (t, J = 8.0 Hz, 2H, Ar–H), 7.64 (t, J = 8.6 Hz, 1H, Ar–H), 7.94 (t, J = 8.2 Hz, 2H, Ar–H), 8.01 (t, J = 7.6 Hz, 2H, Ar–H), 8.10 (s, 1H, CH⚌C), 8.49 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.1, 19.2, 39.6, 110.4, 124.6, 125.6, 127.1, 127.4, 127.8, 128.3, 128.6, 128.9, 129.2, 130.3, 131.5, 135.4, 136.3, 136.7, 141.3, 142.1, 158.6, 160.5, 170.6, 176.4; LCMS (m/z): 493 (M⁺); Anal. Calcd. For C₂₈H₂₃N₅O₂S: C-68.13, H-4.70, N-14.19; Found: C-68.20, H-4.76, N-14.14%.

2.4.12

2.4.12 2-((1-(4-(4-(3-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4l)

Yield: 60%; m.p.: 184–186 °C; IR (KBr) ν_max/cm⁻¹: 3342 (NH), 3064 (C–H, aromatic), 2922, 2870 (C–H), 1687, 1711 (C⚌O), 1585 (C⚌N), 1512 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.38 (s, 3H, CH₃), 2.87 (s, 3H, CH₃), 3.94 (s, 2H, CH₂), 7.05 (s, 1H, Ar–H), 7.12 (d, J = 8.6 Hz, 1H, Ar–H), 7.20 (t, J = 7.2 Hz, 1H, Ar–H), 7.39 (d, J = 7.6 Hz, 2H, Ar–H), 7.45 (d, J = 8.4 Hz, 1H, Ar–H), 7.54 (t, J = 8.6 Hz, 2H, Ar–H), 7.63 (t, J = 8.2 Hz, 1H, Ar–H), 7.81 (s, 1H, CH⚌C), 7.92 (t, J = 8.6 Hz, 2H, Ar–H), 8.13 (t, J = 7.4 Hz, 2H, Ar–H), 8.57 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.1, 21.7, 39.5, 114.6, 124.2, 125.6, 126.6, 127.3, 128.1, 128.3, 128.5, 128.8, 129.2, 130.5, 131.2, 135.3, 135.5, 138.4, 141.1, 142.6, 158.1, 160.6, 170.7, 176.1; LCMS (m/z): 493 (M⁺); Anal. Calcd. For C₂₈H₂₃N₅O₂S: C-68.13, H-4.70, N-14.19; Found: C-68.08, H-4.64, N-14.25%.

2.4.13

2.4.13 2-((1-(4-(4-(4-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4m)

Yield: 52%; m.p.: 196–198 °C; IR (KBr) ν_max/cm⁻¹: 3348 (NH), 3058 (C–H, aromatic), 2927, 2875 (C–H), 1683, 1706 (C⚌O), 1587 (C⚌N), 1518 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.34 (s, 3H, CH₃), 2.94 (s, 3H, CH₃), 3.96 (s, 2H, CH₂), 7.12 (d, J = 8.0 Hz, 2H, Ar–H), 7.46 (d, J = 8.2 Hz, 2H, Ar–H), 7.52 (t, J = 7.8 Hz, 2H, Ar–H), 7.63 (d, J = 8.6 Hz, 2H, Ar–H), 7.69 (t, J = 8.6 Hz, 1H, Ar–H), 7.84 (s, 1H, CH⚌C), 7.96 (d, J = 7.6 Hz, 2H, Ar–H), 8.05 (d, J = 8.4 Hz, 2H, Ar–H), 8.55 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.0, 21.1, 39.3, 114.4, 124.2, 127.4, 128.1, 128.3, 128.6, 128.8, 129.4, 130.7, 131.4, 132.4, 135.6, 137.7, 141.7, 142.4, 158.6, 160.1, 170.2, 176.5; LCMS (m/z): 493 (M⁺); Anal. Calcd. For C₂₈H₂₃N₅O₂S: C-68.13, H-4.70, N-14.19; Found: C-68.21, H-4.65, N-14.24%.

2.4.14

2.4.14 2-((1-(4-(4-(2-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4n)

Yield: 56%; m.p.: 224–226 °C; IR (KBr) ν_max/cm⁻¹: 3354 (NH), 3067 (C–H, aromatic), 2932, 2870 (C–H), 1687, 1712 (C⚌O), 1584 (C⚌N), 1514 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.91 (s, 3H, CH₃), 3.74 (s, 3H, CH₃), 3.96 (s, 2H, CH₂), 6.88 (d, J = 7.2 Hz, 1H, Ar–H), 6.95 (t, J = 8.4 Hz, 1H, Ar–H), 7.25 (t, J = 8.2 Hz, 1H, Ar–H), 7.45 (d, J = 8.6 Hz, 2H, Ar–H), 7.53 (t, J = 8.4 Hz, 2H, Ar–H), 7.60 (t, J = 8.8 Hz, 1H, Ar–H), 7.69 (d, J = 7.6 Hz, 1H, Ar–H), 7.96 (t, J = 8.0 Hz, 2H, Ar–H), 8.04 (t, J = 7.6 Hz, 2H, Ar–H), 8.10 (s, 1H, CH⚌C), 8.57 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.5, 39.2, 54.8, 110.1, 114.4, 114.6, 121.3, 124.4, 127.2, 128.5, 128.6, 128.7, 128.9, 129.3, 130.5, 131.2, 135.5, 141.7, 142.3, 158.1, 159.4, 160.6, 170.2, 176.7; LCMS (m/z): 509 (M⁺); Anal. Calcd. For C₂₈H₂₃N₅O₃S: C-66.00, H-4.55, N-13.74; Found: C-66.07, H-4.62, N-13.80%.

2.4.15

2.4.15 2-((1-(4-(4-(4-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4o)

Yield: 52%; m.p.: 213–215 °C; IR (KBr) ν_max/cm⁻¹: 3364 (NH), 3063 (C–H, aromatic), 2943, 2876 (C–H), 1683, 1705 (C⚌O), 1581 (C⚌N), 1518 (C⚌C); ¹H NMR (300 MHz, DMSO-d₆, δ, ppm): 2.95 (s, 3H, CH₃), 3.75 (s, 3H, OCH₃), 3.97 (s, 2H, CH₂), 6.93 (d, J = 7.8 Hz, 2H, Ar–H), 7.44 (d, J = 7.6 Hz, 2H, Ar–H), 7.56 (t, J = 8.6 Hz, 2H, Ar–H), 7.61 (t, J = 8.4 Hz, 1H, Ar–H), 7.69 (d, J = 8.4 Hz, 2H, Ar–H), 7.85 (s, 1H, CH⚌C), 7.93 (d, J = 8.2 Hz, 2H, Ar–H), 8.05 (d, J = 8.6 Hz, 2H, Ar–H), 8.58 (s, 1H, D₂O exch., NH); ¹³C NMR (100 MHz, DMSO-d₆, δ, ppm): 16.4, 39.2, 54.2, 114.4, 114.7, 124.1, 127.4, 127.5, 128.6, 128.9, 129.2, 130.1, 130.3, 131.6, 135.6, 141.5, 142.4, 158.5, 159.8, 160.6, 170.7, 176.1; LCMS (m/z): 509 (M⁺); Anal. Calcd. For C₂₈H₂₃N₅O₃S: C-66.00, H-4.55, N-13.74; Found: C-65.95, H-4.49, N-13.68%.

3 Results and discussion

3.1

3.1 Chemistry

The synthetic pathways to obtain the intermediate and target compounds in this study are depicted in Scheme 1. Compounds 4-(arylidene)-2-phenyloxazol-5(4H)-ones (1) were prepared in an excellent yield in one step by Perkin condensation of hippuric acid, different substituted aldehydes and acetic anhydride in the presence of anhydrous sodium acetate. In the second step, intermediate (1) was reacted with p-aminoacetophenone in pyridine and refluxed for 4 h to furnish product 1-(4-acetylphenyl)-4-(arylidene)-2-phenyl-1H-imidazol-5(4H)-ones (2). The key intermediates (3a–o) were synthesized through condensation of equimolar amounts of compound (2) and thiosemicarbazide in methanol and refluxed for 1 h. This Schiff base (3a) was characterized using IR and NMR spectra. IR spectra showed strong absorption bands at 3370 and 3442 cm⁻¹ due to primary amine group. Absorption band at 1330 cm⁻¹ over the range was due to C⚌S stretching vibration. The characteristic signals in ¹H NMR of compound (3a) displayed singlet at δ = 6.43 ppm integrating two protons of the primary amine and proton of the secondary amine appeared as a singlet at δ = 8.70 ppm. ¹³C NMR spectra displayed a signal at 179.4 ppm assignable to thiocarbamoyl carbon (C⚌S). The mass spectrum of (3a) showed a molecular ion peak at m/z = 439 (M⁺) corresponding to a molecular formula C₂₅H₂₁N₅OS. Moreover, the aforementioned schiff bases (3a–o) were cyclized to (4a–o) through their reaction with ethyl bromoacetate in hot ethanol for 1 h. Compound (4a) showed strong absorption bands at 1688 and 1708 cm⁻¹ due to carbonyl group in IR spectra. Absorption band appeared at 3353 cm⁻¹ was due to stretching vibration corresponding to secondary amine. In addition to this, ¹H NMR spectra revealed the appearance of singlet peak at δ = 3.92 ppm integrating two protons of the thiazolidine ring. The characteristic signal of compound (3a) displayed singlet at δ = 8.51 ppm integrating proton of the secondary amine. ¹³C NMR confirmed the proposed structure by appearance of signal at δ = 176.2 ppm due to carbonyl carbon as well as the appearance of signal around δ = 39.5 ppm assignable to methylene group of the thiazolidine ring. Moreover, the mass spectrum of (4a) showed a molecular ion peak at m/z = 479 (M⁺) corresponding to a molecular formula C₂₇H₂₁N₅O₂S.

Synthetic route for the preparation of title compounds (4a–o).

3.2

3.2 Antimicrobial activity

Compounds 4a–o were evaluated against Gram-positive bacteria (Staphylococcus aureus, Staphylococcus pyogenes), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and fungi (Candida albicans, Aspergillus niger and Aspergillus clavatus) strains. The individual minimal inhibitory concentration (MIC, μg/mL) values of test compounds against the test microbes are listed in Table 1 along with MIC values of reference compounds ampicillin (for bacteria) and griseofulvin (for fungi). The results revealed that the majority of the synthesized compounds showed varying degrees of inhibition against the test microorganisms. It was found that compounds 4h (2-OH) and 4n (2-OCH₃) showed excellent activity (50 μg/mL and 25 μg/mL) against the gram-positive bacteria S. aureus and S. pyogenes respectively. Among them compounds 4h (2-OH) and 4n (2-OCH₃) exhibited significant activity against S. aureus with the MIC value of 25 μg/mL comparable to that of the reference drug. Compounds 4m (4-CH₃) and 4h (2-OH) showed excellent activity (12.5 μg/mL and 25 μg/mL) against Gram-negative bacteria E. coli, while 4k (2-CH₃) and 4m (4-CH₃) showed excellent activity (12.5 μg/mL and 25 μg/mL) against P. aeruginosa. MIC values of antifungal activity, showed that most compounds exhibited good inhibition against the three fungal strains. Among them 4h (2-OH), 4j (4-OH), 4m (4-CH₃) and 4n (2-OCH₃) exhibited strong inhibition (100 μg/mL) against C. albicans. Compound 4j showed strong activity (25 μg/mL) against A. niger. Compounds 4m and 4n exhibited excellent activity (25 μg/mL) against A. clavatus.

Table 1 Results of antibacterial and antifungal screening of compounds (4a–o).

Entry	-R	Minimum inhibitory concentration (MIC) in μg/mL ± SD				Minimum inhibitory concentration (MIC) in μg/mL ± SD
Entry	-R	E. coli MTCC 443	P. aeruginosa MTCC 1688	S. aureus MTCC 96	S. pyogenes MTCC 442	C. albicans MTCC 227	A. niger MTCC 282	A. clavatus MTCC 1323
4a	-H	250 ± 3.21	500 ± 2.88^⁎	250 ± 2.05^⁎	500 ± 2.05^⁎	1000 ± 3.60	1000 ± 1.20^⁎⁎	500 ± 4.50^⁎⁎
4b	-2-Cl	250 ± 3.61^⁎	500 ± 1.00^⁎	500 ± 3.05	500 ± 3.46^⁎	1000 ± 2.72^⁎	1000 ± 4.04^⁎	1000 ± 4.16
4c	-4-Cl	100 ± 3.05^⁎⁎	100 ± 1.00^⁎⁎⁎	500 ± 4.04^⁎	250 ± 3.60^⁎	500 ± 4.04^⁎	500 ± 3.70^⁎	1000 ± 1.00^⁎
4d	-2-F	500 ± 1.60^⁎⁎	500 ± 1.60^⁎⁎	500 ± 3.21^⁎	250 ± 3.21^⁎	500 ± 4.35^⁎⁎	1000 ± 4.04^⁎	500 ± 4.04
4e	-4-F	500 ± 2.64^⁎⁎	250 ± 4.04	250 ± 2.04^⁎	500 ± 3.21	500 ± 2.88^⁎	250 ± 4.58^⁎	100 ± 1.50^⁎⁎⁎
4f	-2-NO₂	500 ± 3.60	500 ± 2.04^⁎⁎	250 ± 1.05^⁎	250 ± 4.16^⁎	500 ± 2.18^⁎⁎	500 ± 4.16^⁎	250 ± 3.46
4g	-4NO₂	500 ± 1.20^⁎	250 ± 3.60^⁎⁎	500 ± 1.16^⁎	250 ± 1.92	1000 ± 4.60	100 ± 1.60^⁎⁎	250 ± 2.05^⁎⁎
4h	-2-OH	25 ± 2.44^⁎	50 ± 2.21^⁎⁎	50 ± 4.16^⁎	25 ± 1.78^⁎	100 ± 2.05^⁎⁎	50 ± 3.78	50 ± 3.52^⁎
4i	-3-OH	50 ± 3.78^⁎	500 ± 3.78	250 ± 2.04^⁎⁎	250 ± 3.46	250 ± 1.52^⁎	50 ± 1.60^⁎	100 ± 3.78^⁎
4j	-4-OH	100 ± 1.78^⁎	250 ± 1.21^⁎	100 ± 4.16	50 ± 3.78^⁎⁎	100 ± 1.16^⁎⁎⁎	25 ± 1.18^⁎	50 ± 3.60^⁎
4k	-2-CH₃	50 ± 1.60^⁎⁎	12.5 ± 3.78^⁎	100 ± 2.64^⁎⁎⁎	100 ± 2.64^⁎⁎	250 ± 2.88^⁎	100 ± 1.60^⁎	100 ± 3.78
4l	-3-CH₃	500 ± 5.19^⁎	250 ± 1.04^⁎⁎⁎	500 ± 4.60^⁎	100 ± 3.78^⁎⁎⁎	1000 ± 2.56^⁎	100 ± 2.64^⁎	500 ± 4.72^⁎
4m	-4-CH₃	12.5 ± 4.40	25 ± 3.26	100 ± 3.78^⁎⁎	50 ± 4.61^⁎	100 ± 4.72	50 ± 4.16^⁎⁎	25 ± 1.86^⁎⁎
4n	-2-OCH₃	100 ± 3.60^⁎⁎⁎	50 ± 1.16^⁎	100 ± 4.50^⁎	25 ± 3.60^⁎	100 ± 4.04^⁎	100 ± 4.16^⁎	25 ± 4.04^⁎
4o	-4-OCH₃	100 ± 1.52^⁎	100 ± 2.04^⁎⁎	250 ± 4.04	50 ± 2.05^⁎⁎⁎	500 ± 4.61^⁎⁎	50 ± 4.16	100 ± 1.00^⁎⁎⁎

Ampicillin		100 ± 1.12	100 ± 1.12	250 ± 1.72	100 ± 2.24	–	–	–

Griseofulvin		–	–	–	–	500 ± 0.52	100 ± 1.0	100 ± 1.18

±SD = Standard deviation.

All values are presented as mean of six experiments (n = 6). All significant differences are considered from control value 0.00.

⁎ P < 0.05 significant.

⁎⁎ P < 0.01 moderately significant.

⁎⁎⁎ P < 0.001 extremely significant.

On the basis of structure–activity relationship (SAR) studies, the results suggested that the antimicrobial activity of the imidazole derivatives was markedly influenced by the electron donating substituents and the incorporation of electron donating group caused enhanced activity against most test microorganisms. Compounds 4h, 4j, 4k, 4m and 4n with electron-donating substituents (OH, CH₃ and OCH₃) in the aromatic ring were more active against all test bacteria and fungi than compounds having electron-withdrawing groups. Notably, compounds 4k and 4m showed highest inhibition against bacterial strains E. coli and P. aeruginosa respectively at MIC 12.5 μg/mL. Furthermore, compounds 4h and 4n showed significant inhibition against bacterial strains S. aureus and S. pyogenes at MIC 50 and 25 μg/mL respectively. Compounds 4m and 4n showed highest inhibition against fungal strains C. albicans and A. clavatus. From the data of biological activity, we can presume that, to get most potent antimicrobial agents, compounds must contain electron releasing group as substitution. Therefore the electron releasing groups induced a positive effect and the electron withdrawing groups induced a negative effect on the biological activity.

4 Biological evaluation

4.1

4.1 Antibacterial assay

The newly synthesized compounds (4a–o) were screened for their antibacterial activity against Gram-positive bacteria (S. aureus (MTCC-96), S. pyogenes (MTCC-442)) and Gram-negative bacteria (E. coli (MTCC-443), P. aeruginosa (MTCC-1688). All MTCC cultures were collected from the Institute of Microbial Technology, Chandigarh. The activity of compounds was determined as per the National Committee for Clinical Laboratory Standards (NCCLS) protocol using Mueller Hinton Broth (Becton Dickinson, USA) (Finegold and Garrod, 1995; Desai et al., 2012f). Compounds were screened for their antibacterial activity as primary screening in six sets against E. coli, S. aureus, P. aeruginosa and S. pyogenes at different concentrations of 1000, 500, and 250 μg/mL. The compounds found to be active in primary screening were similarly diluted to obtain 200, 125, 100, 62.5, 50, 25 and 12.5 μg/mL concentrations for secondary screening to test in a second set of dilution against all microorganisms. Inoculum size for test strain was adjusted to 10⁶ CFU/mL (Colony Forming Unit per milliliter) by comparing the turbidity (turbidimetric method). Mueller Hinton Broth was used as nutrient medium to grow and dilute the compound suspension for test bacteria. Two percent DMSO was used as a diluent/vehicle to obtain the desired concentration of synthesized compounds and standard drugs to test upon standard microbial strains. Synthesized compounds were diluted to 1000 μg/mL concentration, as a stock solution. The control tube containing no antibiotic was immediately subcultured [before inoculation] by spreading a loopful evenly over a quarter of the plate of medium suitable for the growth of test organisms. The tubes were then put for incubation at 37 °C for 24 h for bacteria. Ten micrograms per milliliter suspensions was further inoculated on an appropriate media and growth was noted after 24 h and 48 h. The highest dilution (lowest concentration) preventing appearance of turbidity was considered as minimum inhibitory concentration (MIC, μg/mL) i.e. the amount of growth from the control tube before incubation (which represents the original inoculum) was compared. A set of tubes containing only seeded broth and solvent controls were maintained under identical conditions so as to make sure that the solvent had no influence on strain growth. The result of this is greatly affected by the size of inoculum. The test mixture should contain 10⁶ CFU/mL organisms. Standard drug used in the present study was ‘ampicillin’ for evaluating antibacterial activity which showed 100, 100, 250 and 100 μg/mL MIC against E. coli, P. aeruginosa, S. aureus and S. pyogenes respectively.

4.2

4.2 Antifungal assay

The same compounds (4a–o) were tested for antifungal activity as primary screening in six sets against C. albicans, A. niger and A. clavatus at various concentrations of 1000, 500, and 250 μg/mL. The compounds found to be active in primary screening were similarly diluted to obtain 200, 125, 100, 62.5, 50 and 25 μg/mL concentrations for secondary screening to test in a second set of dilution against all microorganisms. Griseofulvin was used as a standard drug for antifungal activity, which showed 500, 100 and 100 μg/mL MIC against C. albicans, A. niger and A. clavatus respectively. For fungal growth, in the present protocol, we have used Sabourauds dextrose broth at 28 °C in an aerobic condition for 48 h.

4.3

4.3 Statistical analysis

Standard deviation value was expressed in terms of ±SD. On the basis of calculated value by using one-way ANOVA method followed by independent two sample t test, it has been observed that differences below 0.001 level were considered as statistically significant.

5 Conclusion

The new compounds (4a–o) presented hereby significantly differ in their corresponding antimicrobial activity depending on the type of substituent. In the course of this study, particularly derivatives possessing electron donating groups such as methyl, methoxy and hydroxy were identified as exhibiting potent groups for antibacterial activity against bacterial strains and antifungal activity against fungal strains. Structure–activity relationship studies showed that the antimicrobial potency is mainly influenced by the substituent at 2 and 4-positions on the benzene ring of imidazole ring. It may be considered as a promising lead for further design and development of new chemical entities. The results described here, merit further investigations in our laboratory using a forward chemical genetics approach for finding lead molecules as antimicrobial agents.

Acknowledgment

We express sincere gratitude to the Department of Chemistry, Mahatma Gandhi Campus, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar for providing research and library facilities.

References

Abdel-Meguid S.S., Metcalf B.W., Carr T.J., Demarsh P., DesJarlais R.L., Fisher S., Green D.W., Ivanoff L., Lambert D.M., . Biochemistry. 1994;33:11671.
Adachi Y., Suzuki Y., Homma N., Fukazawa M., Tamura K., Nishie I., Kuromaru O., . Eur. J. Pharmacol.. 1999;367:267.
Badr M.Z.A., Mahgoub S.A.S., . Indian J. Chem.. 1989;28B:829.
Barry C.E., Slayden R.A., Sampson A.E., Lee R.E., . Biochem. Pharmacol.. 2000;59:221.
Brumfitt W., Hamilton-Miller J.M.T., . Drugs Exp. Clin. Res.. 1994;20:215.
Desai N.C., Maheta A.S., Rajpara K.M., Joshi V.V., Vaghani H.V., Satodiya H.M., . J. Saudi. Chem. Soc. 2011
[CrossRef]
Desai N.C., Joshi V.V., Rajpara K.M., Vaghani H.V., Satodiya H.M., . Med. Chem. Res. 2012
[CrossRef]
Desai N.C., Rajpara K.M., Joshi V.V., Vaghani H.V., Satodiya H.M., . Med. Chem. Res. 2012
[CrossRef]
Desai N.C., Rajpara K.M., Joshi V.V., Vaghani H.V., Satodiya H.M., . Anti-Infect. Agents. 2012;10:75.
Desai N.C., Joshi V.V., Rajpara K.M., Vaghani H.V., Satodiya H.M., . J. Fluor. Chem.. 2012;142:67-78.
Desai N.C., Rajpara K.M., Joshi V.V., . Bioorg. Med. Chem. Lett.. 2012;15:6871.
Desai, N.C., Rajpara, K.M., Joshi, V.V., 2012f. J. Fluor. Chem., http://dx.doi.org/10.1016/j.jfluchem.2012.06.021.
Diurno M.V., Mazzoni O., Capasso F., Izzo A.A., Bolognese A., . Farmaco. 1997;52:237.
Finegold S.M., Garrod L., . Bailey and Scott’s Diagnostic Microbiology (8th ed.). Toronto: C.V. Mosby; 1995. Chapter 13, pp. 171–193
Gangneux J.P., Dullin M., Sulahian A., Garin Y.J.F., Derouin F., . Antimicrob. Agents Chemother.. 1999;43:172.
Ghazzi M.N., Perez J.E., Antonucci T.K., Driscoll J.H., Huang S.M., Faja B.W., Whitcomb R.W., . Diabetes. 1997;46:433.
Havrylyuk D., Zimenkovsky B., Lesyk R., . Phosphorus, Sulfur Silicon Relat. Elem.. 2009;184:638.
Kato T., Ozaki T., Ohi N., . Tetrahedron: Asymmetry. 1999;10:3963.
Kato T., Ozaki T., Tamura K., Suzuki Y., Akima M., Ohi N., . J. Med. Chem.. 1999;42:3134.
Kato Y., Kita Y., Nishio M., Hirasawa Y., Ito K., Yamanaka T., Motoyama Y., Seki J., . Eur. J. Pharmacol.. 1999;384:197.
Laping N.J., Grygielko E., Mathur A., Butter S., Bomberger J., Tweed C., Martin W., Fornwald J., Lehr R., Harling J., Gaster L., Callahan J.F., Olson B.A., . Mol. Pharmacol.. 2002;62:58.
Laufer S.A., Zimmermann W., Ruff K.J., . J. Med. Chem.. 2004;47:6311.
Lisnock J.M., Griffin P., Calaycay J., Frantz B., Parsons J., O'Keefe S.J., LoGrasso P., . Biochemistry. 2002;39:3141.
Muller G., . Drug Discovery Today. 2003;8:681.
Munk S.A., Harcourt D.A., Arasasingham P.N., Burke J.A., Kharlamb A.B., Manlapaz C.A., Padillo E.U., Roberts D., Runde E., Williams L., Wheeler L.A., Garst M.E., . J. Med. Chem.. 1997;40:18.
Nair M.D., Nagarajan K., . Prog. Drug. Res.. 1983;27:163.
Neu H.C., . Science. 1992;257:1064.
Norisada N., Masuzaki H., Fujimoto M., Inoue G., Hosoda K., Hayashi T., Watanabe M., Muraoka S., Yoneda F., Nakao K., . Metabolism. 2004;53:1532.
Ottana R., Mazzon E., Dugo L., Monforte F., Maccari R., Sautebin L., Luca G.De., Vigorita M.G., Alcaro S., Ortuso F., . Eur. J. Pharmacol.. 2002;448:71.
Previtera T., Vigorita M.G., Basile M., Orsini F., Benetollo F., Bombieri G., . Eur. J. Med. Chem.. 1994;29:317-324.
Ragab F.A., Eid N.M., el-Tawab H.A., . Pharmazie. 1997;52:926.
Rawal R.K., Prabhakar Y.S., Katti S.B., DeClercq E., . Bioorg. Med. Chem.. 2005;13:6771.
Riddell D., Bright C.P., Burton B.J., Bush R.C., Harris N.V., Hele D., Moore U.M., Naik K., Parrott D.P., Smith C., Williams R.J., . Biochem. Pharmacol.. 1996;52:1177.
Rubinstein E., . Science. 1994;264:360.
Sattigeri V.J., Soni A., Singhal S., Khan S., Pandya M., Bhateja P., Mathur T., Rattan A., Khanna J., Mehta A., . ARKIVOC. 2005;2:46.
Takle A.K., Brown M.J., Davies S., Dean D.K., Francis G., Gaiba A., Hird A.W., King F.D., Lovell P.J., Naylor A., Reith A.D., Steadman J.G., Wilson D.M., . Bioorg. Med. Chem. Lett.. 2006;16:378.
Tanabe Y., Suzukamo G., Komuro Y., Imanishi N., Morooka S., Enomoto M., Kojima A., Sanemitsu Y., Mizutani M., . Tetrahedron Lett.. 1991;32:379.
Tanabe Y., Yamamoto H., Murakami M., Yanagi K., Kubota Y., Okumura H., Sanemitsu Y., Suzukamo G., . J. Chem. Soc., Perkin Trans.. 1995;1:935.
Ulrich S., Roland U., Albrecht L., Helmut G., Bernd P., Johanna B., Karin W., Peter F., . Synthesis. 1987;3:233-236.
Voss M.E., Carter P.H., Tebben A.J., Scherle P.A., Brown G.D., Thampson L.A., Xu M., Lo Y.C., Liu R.Q., Strzemienski P., Everlof J.G., Trzaskos J.M., Decicco C.P., . Bioorg. Med. Chem. Lett.. 2003;13:533.

Show Sections

[1] Abdel-Meguid S.S., Metcalf B.W., Carr T.J., Demarsh P., DesJarlais R.L., Fisher S., Green D.W., Ivanoff L., Lambert D.M., . Biochemistry. 1994;33:11671.

[2] Adachi Y., Suzuki Y., Homma N., Fukazawa M., Tamura K., Nishie I., Kuromaru O., . Eur. J. Pharmacol.. 1999;367:267.

[3] Badr M.Z.A., Mahgoub S.A.S., . Indian J. Chem.. 1989;28B:829.

[4] Barry C.E., Slayden R.A., Sampson A.E., Lee R.E., . Biochem. Pharmacol.. 2000;59:221.

[5] Brumfitt W., Hamilton-Miller J.M.T., . Drugs Exp. Clin. Res.. 1994;20:215.

[6] Desai N.C., Maheta A.S., Rajpara K.M., Joshi V.V., Vaghani H.V., Satodiya H.M., . J. Saudi. Chem. Soc. 2011
[CrossRef]

[7] Desai N.C., Joshi V.V., Rajpara K.M., Vaghani H.V., Satodiya H.M., . Med. Chem. Res. 2012
[CrossRef]

[8] Desai N.C., Rajpara K.M., Joshi V.V., Vaghani H.V., Satodiya H.M., . Med. Chem. Res. 2012
[CrossRef]

[9] Desai N.C., Rajpara K.M., Joshi V.V., Vaghani H.V., Satodiya H.M., . Anti-Infect. Agents. 2012;10:75.

[10] Desai N.C., Joshi V.V., Rajpara K.M., Vaghani H.V., Satodiya H.M., . J. Fluor. Chem.. 2012;142:67-78.

[11] Desai N.C., Rajpara K.M., Joshi V.V., . Bioorg. Med. Chem. Lett.. 2012;15:6871.

[12] Desai, N.C., Rajpara, K.M., Joshi, V.V., 2012f. J. Fluor. Chem., http://dx.doi.org/10.1016/j.jfluchem.2012.06.021.

[13] Diurno M.V., Mazzoni O., Capasso F., Izzo A.A., Bolognese A., . Farmaco. 1997;52:237.

[14] Finegold S.M., Garrod L., . Bailey and Scott’s Diagnostic Microbiology (8th ed.). Toronto: C.V. Mosby; 1995. Chapter 13, pp. 171–193

[15] Gangneux J.P., Dullin M., Sulahian A., Garin Y.J.F., Derouin F., . Antimicrob. Agents Chemother.. 1999;43:172.

[16] Ghazzi M.N., Perez J.E., Antonucci T.K., Driscoll J.H., Huang S.M., Faja B.W., Whitcomb R.W., . Diabetes. 1997;46:433.

[17] Havrylyuk D., Zimenkovsky B., Lesyk R., . Phosphorus, Sulfur Silicon Relat. Elem.. 2009;184:638.

[18] Kato T., Ozaki T., Ohi N., . Tetrahedron: Asymmetry. 1999;10:3963.

[19] Kato T., Ozaki T., Tamura K., Suzuki Y., Akima M., Ohi N., . J. Med. Chem.. 1999;42:3134.

[20] Kato Y., Kita Y., Nishio M., Hirasawa Y., Ito K., Yamanaka T., Motoyama Y., Seki J., . Eur. J. Pharmacol.. 1999;384:197.

[21] Laping N.J., Grygielko E., Mathur A., Butter S., Bomberger J., Tweed C., Martin W., Fornwald J., Lehr R., Harling J., Gaster L., Callahan J.F., Olson B.A., . Mol. Pharmacol.. 2002;62:58.

[22] Laufer S.A., Zimmermann W., Ruff K.J., . J. Med. Chem.. 2004;47:6311.

[23] Lisnock J.M., Griffin P., Calaycay J., Frantz B., Parsons J., O'Keefe S.J., LoGrasso P., . Biochemistry. 2002;39:3141.

[24] Muller G., . Drug Discovery Today. 2003;8:681.

[25] Munk S.A., Harcourt D.A., Arasasingham P.N., Burke J.A., Kharlamb A.B., Manlapaz C.A., Padillo E.U., Roberts D., Runde E., Williams L., Wheeler L.A., Garst M.E., . J. Med. Chem.. 1997;40:18.

[26] Nair M.D., Nagarajan K., . Prog. Drug. Res.. 1983;27:163.

[27] Neu H.C., . Science. 1992;257:1064.

[28] Norisada N., Masuzaki H., Fujimoto M., Inoue G., Hosoda K., Hayashi T., Watanabe M., Muraoka S., Yoneda F., Nakao K., . Metabolism. 2004;53:1532.

[29] Ottana R., Mazzon E., Dugo L., Monforte F., Maccari R., Sautebin L., Luca G.De., Vigorita M.G., Alcaro S., Ortuso F., . Eur. J. Pharmacol.. 2002;448:71.

[30] Previtera T., Vigorita M.G., Basile M., Orsini F., Benetollo F., Bombieri G., . Eur. J. Med. Chem.. 1994;29:317-324.

[31] Ragab F.A., Eid N.M., el-Tawab H.A., . Pharmazie. 1997;52:926.

[32] Rawal R.K., Prabhakar Y.S., Katti S.B., DeClercq E., . Bioorg. Med. Chem.. 2005;13:6771.

[33] Riddell D., Bright C.P., Burton B.J., Bush R.C., Harris N.V., Hele D., Moore U.M., Naik K., Parrott D.P., Smith C., Williams R.J., . Biochem. Pharmacol.. 1996;52:1177.

[34] Rubinstein E., . Science. 1994;264:360.

[35] Sattigeri V.J., Soni A., Singhal S., Khan S., Pandya M., Bhateja P., Mathur T., Rattan A., Khanna J., Mehta A., . ARKIVOC. 2005;2:46.

[36] Takle A.K., Brown M.J., Davies S., Dean D.K., Francis G., Gaiba A., Hird A.W., King F.D., Lovell P.J., Naylor A., Reith A.D., Steadman J.G., Wilson D.M., . Bioorg. Med. Chem. Lett.. 2006;16:378.

[37] Tanabe Y., Suzukamo G., Komuro Y., Imanishi N., Morooka S., Enomoto M., Kojima A., Sanemitsu Y., Mizutani M., . Tetrahedron Lett.. 1991;32:379.

[38] Tanabe Y., Yamamoto H., Murakami M., Yanagi K., Kubota Y., Okumura H., Sanemitsu Y., Suzukamo G., . J. Chem. Soc., Perkin Trans.. 1995;1:935.

[39] Ulrich S., Roland U., Albrecht L., Helmut G., Bernd P., Johanna B., Karin W., Peter F., . Synthesis. 1987;3:233-236.

[40] Voss M.E., Carter P.H., Tebben A.J., Scherle P.A., Brown G.D., Thampson L.A., Xu M., Lo Y.C., Liu R.Q., Strzemienski P., Everlof J.G., Trzaskos J.M., Decicco C.P., . Bioorg. Med. Chem. Lett.. 2003;13:533.

A new synthetic approach and in vitro antimicrobial evaluation of novel imidazole incorporated 4-thiazolidinone motifs

Abstract

Keywords

Imidazole

4-Thiazolidinone

Antibacterial activity

Antifungal activity

MIC

1 Introduction

2 Experimental

2.1 General

2.2 General procedure for preparation 1-(4-acetylphenyl)-4-(arylidene)-2-phenyl-1H-imidazol-5(4H)-ones (2a-o)

2.3 General procedure for preparation 2-(1-(4-(4-(arylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazinecarbothioamides (3a-o)

2.3.1 2-(1-(4-(4-Benzylidene-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazine carbothioamide (3a)

2.3.2 2-(1-(4-(4-(2-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3b)

2.3.3 2-(1-(4-(4-(4-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3c)

2.3.4 2-(1-(4-(4-(2-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3d)

2.3.5 2-(1-(4-(4-(4-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3e)

2.3.6 2-(1-(4-(4-(2-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3f)

2.3.7 2-(1-(4-(4-(4-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3g)

2.3.8 2-(1-(4-(4-(2-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3h)

2.3.9 2-(1-(4-(4-(3-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3i)

2.3.10 2-(1-(4-(4-(4-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3j)

2.3.11 2-(1-(4-(4-(2-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3k)

2.3.12 2-(1-(4-(4-(3-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3l)

2.3.13 2-(1-(4-(4-(4-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3m)

2.3.14 2-(1-(4-(4-(2-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3n)

2.3.15 2-(1-(4-(4-(4-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazinecarbothioamide (3o)

2.4 General procedure for preparation 2-((1-(4-(4-(arylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl) ethylidene)hydrazono)thiazolidin-4-ones (4a-o)

2.4.1 2-((1-(4-(4-Benzylidene-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene)hydrazono) thiazolidin-4-one (4a)

2.4.2 2-((1-(4-(4-(2-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4b)

2.4.3 2-((1-(4-(4-(4-Chlorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4c)

2.4.4 2-((1-(4-(4-(2-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4d)

2.4.5 2-((1-(4-(4-(4-Fluorobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4e)

2.4.6 2-((1-(4-(4-(2-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4f)

2.4.7 2-((1-(4-(4-(4-Nitrobenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4g)

2.4.8 2-((1-(4-(4-(2-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4h)

2.4.9 2-((1-(4-(4-(3-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4i)

2.4.10 2-((1-(4-(4-(4-Hydroxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4j)

2.4.11 2-((1-(4-(4-(2-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4k)

2.4.12 2-((1-(4-(4-(3-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4l)

2.4.13 2-((1-(4-(4-(4-Methylbenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4m)

2.4.14 2-((1-(4-(4-(2-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4n)

2.4.15 2-((1-(4-(4-(4-Methoxybenzylidene)-5-oxo-2-phenyl-4,5-dihydro-1H-imidazol-1-yl)phenyl)ethylidene) hydrazono)thiazolidin-4-one (4o)

3 Results and discussion

3.1 Chemistry

3.2 Antimicrobial activity

4 Biological evaluation

4.1 Antibacterial assay

4.2 Antifungal assay

4.3 Statistical analysis

5 Conclusion

Acknowledgment

References

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