Translate this page into:
Chemical composition, antibacterial and repellent activities of Azorella trifurcata, Senecio pogonias, and Senecio oreophyton essential oils
⁎Corresponding author at: Instituto de Biotecnología, Facultad de Ingeniería, Universidad Nacional de San Juan, Av. Libertador General San Martín 1109 oeste, 5400 San Juan, Argentina. Tel.: +54 264 4211700x294; fax: +54 2644213672. atapia@unsj.edu.ar (Alejandro Tapia)
-
Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Abstract
The antibacterial and insect-repellent activities of the essential oils (EOs) from Argentinian medicinal plants Azorella trifurcata (Gaertn.) Pers., Senecio cfr. oreophyton J. Remy and Senecio cfr. pogonias Cabrera, were investigated. All EOs showed good repellent properties against Triatoma infestans Klug, the vector of the Chagas disease, with percent repellence values between 60% and 70% at 24 h compared with positive control N-N diethyl-m-methylbenzamide (DEET) and moderate activity against the bacteria tested with minimum inhibitory concentration (MIC) values between 31.2 and 2000 μg/ml. The A. trifurcata, Senecio pogonias and Senecio oreophyton EOs, obtained by hydrodistillation, were characterized by GC-FID and GC/MS analyses. Spathulenol (38.2%), myrtenyl acetate (8.4%), α-terpineol (4.5%), limonene (9.8%) and α-thujene (5.4%) were the main constituents in the EO of A. trifurcata. The S. pogonias and S. oreophyton EOs are characterized by a high content of monoterpene hydrocarbons (92% and 95.1%, respectively) with α-pinene, the main component in both oils. To our knowledge, the essential oil composition from Andean medicinal plants A. trifurcata, S. pogonias and S. oreophyton collected in central Andean slopes are reported for the first time.
Keywords
Azorella trifurcata
Senecio oreophyton
Essential oil
Triatoma infestans
Chagas disease
Escherichia coli
Dedicated to the memory of Ing. Francisco Benavente (Facultad de Ingeniería, Universidad Nacional de San Juan, Argentina).
1 Introduction
The Province of San Juan is located in the central-western part of Argentina, centred at the intersection of 31° S latitude and 69° W longitudes to the western Andean slopes. The province has a rich tradition in folk medicine including the use of medicinal plants. The flora from ecosystem Andino in Argentine comprises a large number of species distributed in different ecosystems, characterized by particular edaphic and climatic conditions. Plants of the high mountains have been used as medicines since pre-hispanic times and are still used for their reputed therapeutic properties, including Azorella, Senecio, Baccharis and Larrea genus, to treat mainly digestive and hepatic disorders, fever, coughs and colds (Bustos et al., 1996; Feresin et al., 2002).
The Azorella genus comprises about 30 species growing in the Andean mountains and Patagonia, Argentina, and only 15 species are recognized in this country (Martinez, 1989). Several authors have reported the chemical composition of the Chilean species A. madreporica, A. yareta, and A. compacta (Loyola et al., 1997a,b,c, 1998a,b, 2002). The biological activities such as: antiplasmodial, trichonomicidal, antituberculosis and antibacterial, have been evaluated by azorellane and mulinane diterpenoids, and isolated by the different Azorella species (Wächter et al., 1999; Loyola et al., 2001, 2004; Molina-Salinas et al., 2010). Azorella trifurcata, commonly known as “yareta” distributed in Argentina and Chile is used to treat digestive disorders. Recently, triterpenoids isolated from A. trifurcata (Gaertn.) Pers and their effect against the enzyme acetylcholinesterase were reported (Areche et al., 2010). Also, their in vitro spermatostatic activity of mulinane- and azorellane-type diterpenes on human spermatozoa (Chiaramello et al., 2011) was reported.
Regarding Senecio genus, there are about 3000 species around the world, mainly in hilly areas. In Argentina there are more than 270 species; most of them in the Andes Mountain and in Patagonia (Cabrera, 1971). The chemical composition of the essential oils of some Senecio species including S. trapezuntinus, S. platyphyllus, S. vernalis, S. glaucus, S. leucostachys, S. squalidus, S. aegyptius, S. graveolens, S farfarifolius, S. nutans, S. rufinervis, and S. longipenicillatus are reported (Kahriman et al., 2011; Mishra et al., 2011). The species, Senecio cfr pogonias, and S. cfr oreophyton n.v. “chachacoma” are used in traditional medicine of Argentine to treat hepatic disorders, fever, coughs and colds. To our knowledge, so far, the biological activities and chemical composition of A. trifurcata, Senecio oreophyton and S. pogonias essential oils (EOs) collected in the central Andean zone of Argentina have not yet been reported.
Is recognized, that the infectious diseases caused by bacteria, virus, fungi, and parasites, are a significant threat to public health (WHO, 2014). Thus, the natural products, specially the EOs and their components, are an alternative for this type of affections.
We report the chemical composition, repellent against T. infestans “Chagas disease” vector and antimicrobial activity of essential oils of A. trifurcata, S. oreophyton, and S pogonias collected in the central Andean mountain from San Juan Province, Argentine.
2 Materials and methods
2.1 Plant materials
Samples of A. trifurcata (Gaertn.) Pers. (Apiaceae), Senecio cfr. oreophyton J. Remy and Senecio cfr. pogonias Cabrera (Asteraceae) were collected from Iglesia (Quebrada de Romo) district in the Central Andes area, from San Juan Province, Argentina, during the flowering period (2011). Species were identified by Dr. Luis Ariza Espinar (Instituto Multidisciplinario de Biología Vegetal, CONICET, and Universidad Nacional de Córdoba). Voucher specimens were deposited with the Museo Botánico de Córdoba, Argentina and were identified as CORD 9745, CORD 9748 and CORD 9747 code, respectively.
2.2 Isolation of essential oils
Fresh aerial parts (500 g) were finely grinded and subjected to hydro distillation in a Clevenger apparatus for 1 h, according to the method recommended by the European Pharmacopoeia (Council of Europe (COE, 2005). Yields were averaged over four distillations and calculated according to dry weight of the plant material. Essential oils (EOs) were stored at −18 °C in airtight micro tubes prior to analysis by gas chromatography (GC) and chromatography–mass spectrometry (GC/MS).
2.2.1 Chemical characterization of the essential oils. GC Analysis
GC analyses were performed with a Shimadzu GC-R1A apparatus equipped with a flame ionization detector (FID) and a DB-5 fused-silica cap. Column (30 m × 0.25 mm i.d., film thickness 0.25 mm) is coated with a non polar 5% phenyl/95% dimethylpolysiloxane phase. The oven temp was programmed from 40 to 2308 at 28/min; injector and detector temp., 2408; carrier gas, N2 (0.9 ml/min). The identification of the components was based on the comparison of their retention indices (RIs) with those of a homologous series of n-alkanes (C9–C25) and of pure authentic samples.
2.2.2 GC–MS Analysis of essential oils
The essential oils were analysed by GC/MS. Mass spectra were obtained on a Perkin Elmer Clarus 600 mass spectrometer, coupled directly to Perkin Elmer Series Clarus 600 gas chromatograph fitted with a fused silica DB-5 MS capillary column (60 m, 0.25 mm i.d., film thickness 0.25 μm) and by using helium as a carrier gas (49.6 psi). The split injection mode was selected. Samples were analysed at oven temperature programme: initial temperature was 60 °C (held for 5 min), 5 °C min to 240 °C (held for 10 min). A column head pressure of 15 psi and an injector temperature and FID detector of 250 °C were used. The GC transfer line was maintained at 200 °C. Ionization was carried out in the mass spectrometer under vacuum by electron impact with a 70 eV ionization energy. Chromatograms were acquired in “scan” mode, scanning the quadrupole from m/z 50 to m/z 300 (scan time: 0.2 s, inter-scan time: 0.1 s).
Identification of the components was done comparing their mass spectra with those reported in the literature and by computer matching with the Wiley 8 and Adams libraries and co-injection with authentic compounds whenever possible (Adams, 2007).
2.3 Repellent activity against T. infestans nymphs
2.3.1 Insects
T. infestans Klug nymphs were provided by Servicio Nacional de Chagas (Córdoba, Argentina) at the fifth instar. Nymphs were used one day after receipt.
2.3.2 Repellent activity test
Bioassays were done according to Talukder and Howse (Talukder and Howse, 1994). Filter paper discs (9 cm diameter) divided by halves were used. One half was treated with 0.5 ml of acetone solutions of the essential oils (0.5% w/v) and the remaining half was left untreated. As control, circular white filter papers divided into two halves, one treated with 0.5 ml of acetone and the other untreated, were used. After solvent evaporation, filter paper discs were placed covering the floor of a Petri dish. Five starved nymphs of T. infestans (fifth instar) were released in the centre of each Petri dish and maintained under controlled conditions of temperature 24 ± 2 °C, 50 ± 5% RH and photoperiod of 16 h L/8 h D. Experiments were performed by quintuplicate. The insect’s distribution was recorded at 1, 24 and 72 h of treatment. Data were transformed into repellency percentage (RP) as: Where Nc represents percentage of nymphs on the blank half of the filter-paper disc.
Positive values show repellence while negative values show attraction. Mean values were categorised according to the following scale: Class 0 (>0.01 to <0.1), I (0.1 to 20), II (20.1 to 40); III (40.1 to 60); IV (60.1 to 80), V (80.1 to 100). Data were analysed by repeated measures ANOVA to determine the overall significance of the repellence means between the time points and the effect of oil treatment as a factor between subjects. Data were analysed with the statistical software SPSS 15.0 (SPPSS Inc.).
2.4 Antibacterial activity
2.4.1 Microorganisms
The following bacterial strains were used: Escherichia coli ATCC 25922, Escherichia coli LM1 (LM: Laboratorio de Microbiología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina). Escherichia coli 712, E. coli 121, E. coli 782, Enterobacter sp., Pseudomonas sp., Klebsiella pneumoniae ss. pneumoniae, Klebsiella pneumoniae ss. pneumoniae 94-1, Staphylococcus coagulaase negative, and Proteus mirabilis (Laboratorio de Microbiología, Hospital Marcial Quiroga, San Juan, Argentina).
2.4.2 Antibacterial activity test
Minimum inhibitory concentration (MIC) was determined using the microbroth dilution method according to the protocols of the Clinical and Laboratory Standards Institute (CLSI, 2008). All tests were performed in Mueller–Hinton broth (MHB), and cultures of each strain were prepared overnight. Microorganism suspensions were adjusted in a spectrophotometer with sterile physiological solutions to give a final organism density of 0.5 Mc Farland scale (1–5 × 105 CFU/ml). Stock solutions of EOs in DMSO were diluted to give serial two-fold dilutions that were added to each medium to obtain final concentrations ranging from 2000 to 32.5 μg/ml. The final concentration of DMSO in the assay did not exceed 1%. The antimicrobial agent cefotaxime (Argentina Pharmaceutica) is used as a positive control. Tests were done in triplicate and values of MIC are expressed in μg/ml.
3 Results and discussion
Hydrodistillation of the fresh leaves and stems of A. trifurcata, S. pogonias and, S. oreophyton gave pale yellow and green essential oils in yields of 1.0%, 0.4%, and 1.0% (w/v) respectively. EO components and relative percentages analysed by GC/FID and GC/MS of A. trifurcata with a total of 25 constituents that represented 98.2% of the total essential oil are shown in Table 1. The monoterpenes represented the main fraction of the essential oils accounting for 49.5%, characterized by a high percentage of oxygenated monoterpenes (28.5%) and monoterpene hydrocarbons (21%). Spathulenol (38.2%), myrtenyl acetate (8.4%), α-terpineol (4.5%), limonene (9.8%), and α-thujene (5.4%) were the main compounds identified, while that the hydrocarbon sesquiterpenes accounted for 10.5%. Among them, the most abundant was α-guaiene (7.5%) and β-caryophyllene (3.0%).
| RIa | Compound | Compositionb (%) | Identificationc | ||
|---|---|---|---|---|---|
| A. trifurcata | S. pogonias | S. oreophyton | |||
| 931 | α-Thujene | 5.4 | tr | 0.6 | |
| 939 | α-Pinene | – | 48.0 | 40.0 | Co |
| 950 | α-Fenchene | 1.2 | tr | tr | |
| 953 | Camphene | – | – | tr | |
| 974 | Sabinene | 0.4 | 1.7 | 2.2 | |
| 980 | β-Pinene | 0.5 | 5.9 | 4.8 | Co |
| 990 | β-Myrcene | 0.6 | 2.7 | 2.6 | Co |
| 992 | 2,3-Dehydro-1,8-cineole | – | 0.4 | tr | |
| 1003 | α-Phellandrene | 1.3 | 22.0 | 1.7 | |
| 1004 | p-Mentha-1(7),8-diene | – | 0.5 | 31.0 | |
| 1015 | α-Terpinene | – | 1.1 | 0.4 | |
| 1026 | p-Cymene | 1.8 | 7.1 | 1.8 | Co |
| 1028 | o-Cymene | – | – | 2.4 | Co |
| 1030 | Limonene | 9.8 | 0.9 | 1.8 | Co |
| 1031 | β-Phellandrene | tr | 1.0 | 5.3 | |
| 1033 | 1,8-Cineole | 2.0 | 1.3 | 0.3 | Co |
| 1057 | o-Cresol | 2.3 | – | – | Co |
| 1062 | γ-Terpinene | – | 0.6 | tr | |
| 1090 | Terpinolene | – | 0.5 | 0.5 | Co |
| 1124 | 4-Terpinenyl acetate | – | tr | – | |
| 1124 | α-Campholenal | 0.2 | tr | tr | |
| 1138 | trans-Pinocarveol | 0.4 | 0.3 | tr | |
| 1140 | cis-Verbenol | 0.6 | tr | tr | |
| 1145 | Camphor | 0.7 | tr | – | Co |
| 1161 | trans-3-Pinanone | – | tr | – | |
| 1166 | Pinocarvone | – | tr | – | |
| 1171 | Borneol | 0.3 | – | – | Co |
| 1178 | 4-Terpineol | 1.2 | 0.4 | 0.5 | Co |
| 1187 | Cryptone | 0.2 | – | – | |
| 1191 | α-Terpineol | 4.5 | 1.4 | 0.4 | Co |
| 1197 | Myrtenol | tr | – | – | |
| 1225 | β-Citronellol | 3.3 | – | – | |
| 1230 | cis-Carveol | – | 0.4 | tr | |
| 1254 | Piperitone | – | 1.4 | 0.5 | |
| 1255 | cis-Geraniol | 2.0 | – | – | Co |
| 1290 | Thymol | 2.4 | – | – | Co |
| 1330 | Myrtenyl acetate | 8.4 | – | – | |
| 1390 | β-Elemene | – | tr | tr | |
| 1420 | β-Caryophyllene | 3.0 | tr | 0.5 | |
| 1442 | α-Guaiene | 7.5 | – | – | |
| 1478 | Spathulenol | 38.2 | – | – | |
| Total | 98.2 | 97.6 | 97.3 | ||
| Monoterpene hydrocarbons | 21.0 | 92 | 95.1 | ||
| Oxygenated monoterpenes | 28.5 | 5.6 | 1.7 | ||
| Sesquiterpene hydrocarbons | 10.5 | 0 | 0.5 | ||
| Oxygenated sesquiterpenes | 38.2 | 0 | 0 | ||
Regarding chemical composition of essential oils of both species of Senecio (Table 1), a total of 19 and 18 compounds amounting 97.6% and 97.3% were identified in the EOs from S. pogonias and S. oreophyton, respectively. The EOs are characterized by a high content of monoterpenes hydrocarbons (92% and 95.1%) in S. pogonias, and S. oreophyton, respectively, being α-pinene, the main component in both oils. Besides the essential oil of S. pogonias was characterized by other main component as α-phellandrene (22.0%), p-cymene (7.1%) and β-pinene (5.9%), while that S. oreophyton essential oil contains p-mentha-1(7), 8-diene (31%), and β-phellandrene (5.3%) as other major constituents.
3.1 Repellent activity of essential oils on T. infestans nymphs
Repellents are substances that act locally or at a distance, deterring an arthropod from flying to, landing on or biting human or animal skin (or a surface in general) (Blackwell et al., 2003; Choochote et al., 2007).
The repellent activity at 1, 24 and 72 h after treatment against T. infestans nymphs of A. trifurcata, S. oreophyton and S. pogonias EOs from Central Andes Argentina, are summarized in Table 2. According to the repeated measures ANOVA with a Greenhouse–Geisser correction, the repellent percentage differed significantly between time points (P < 0.05). Significant differences were observed between the oil treatment and control (effects between-subjects, P < 0.05). A. trifurcata and S. oreophyton EOs were found to be Class III repellents, while the S. pogonias showed a high repellency (class IV).
| Repellency (%) at 0.5%a (w/v) | Average RPb | Classc | |||
|---|---|---|---|---|---|
| 1 h | 24 h | 72 h | |||
| A. trifurcata | 20.00 ± 25.30 | 76.00 ± 9.8 | 68.00 ± 19.60 | 54 | III |
| S. pogonias | 76.00 ± 16.00 | 60 ± 21.91 | 68 ± 14.97 | 68 | IV |
| S. oreophyton | 36.00 ± 9.80 | 68.00 ± 8.00 | 36.00 ± 14.97 | 46.6 | III |
| DEETd | 100 ± 0.0 | 100 ± 0.0 | 100 ± 0.0 | 100 | V |
Regarding the repellence percentage (RP) after 72-h treatment, the most repellent EOs were S. pogonias and A. trifurcata (68% RP). On the other hand, S. oreophyton essential oil repellency showed a peak within 24 h (68%) however, at 72 h this value declined (36%).
Recently, the repellent activity of EOs of G. polycephalum and A. cryptantha (Apiaceae), from Argentinian Central Andes was reported on nymphs of T. infestans (Lima et al., 2011; López et al., 2012).
A. trifurcata, S. pogonias and S. oreophyton EOs repellent activity may be due to the presence of terpenes as spathulenol, limonene, α-pinene, α-phellandrene, and p-cymene because of their recognized insect repellent properties. In bite deterrent studies, spathulenol, intermedeol, and callicarpenal showed significant repellent activity against Aedes aegypti and Anopheles stephensi (Cantrell et al., 2005). In a previous report on aromatic plants collected in the central west of Argentina, Gillij et al., 2008 suggest that limonene and camphor are the main components responsible for the repellent effect against A. aegypti. In addition, some monoterpenes such as α-pinene, cineole, eugenol, limonene, terpinolene, citronellol, citronellal, camphor, and thymol are common constituents of a numerous EOs described in the literature, as presenting mosquito repellent activity (Ibrahim and Zaki, 1998; Yang et al., 2004; Park et al., 2005; Jaenson et al., 2006). Comparisons of larvicidal data revealed that α-phellandrene, limonene, p-cymene, c-terpinene, terpinolene, and a-terpinene examined in this study exhibited great larvicidal performance against A. aegypti and A. albopictus (Cheng et al., 2009).
However, the bioactivity of the EO depends upon the type and nature of their constituents and individual concentration. It further varies with species, season, location, climate, and soil type, age of the leaves, fertility regime, the method used for drying the plant material, and the method of oil extraction (Brooker and Kleinig, 2006). EOs from A. trifurcata, S. pogonias, and S. oreophyton collected in Argentinian Central Andean may be potential alternative repellents to T. infestans (Klug) (Hemiptera, Reduviidae), the vector of Chagas disease, since they constitute a rich source of bioactive compounds that are biodegradable into non toxic products.
3.2 Antibacterial activity of essential oils
The antibacterial activity of the essential oils was evaluated against Gram-positive bacteria and Gram-negative bacteria. Their activity potential was assessed qualitatively by minimum inhibitory concentration (MIC) values. The antibacterial activity of EOs from Argentinian medicinal plants A. trifurcata, S. pogonias, and S. oreophyton are shown in Table 3. From them, the EO of A. trifurcata was the most active against Pseudomonas sp. Staphylococcus coagulase negative 968 with MICs values of 500 μg/ml and 1000 μg/ml respectively. EOs from A. trifurcata, S. pogonias, and S. oreophyton showed antibacterial activity towards enterobacterium E. coli ATCC 25922 and E. coli-LM-1 clinical isolate with equal MIC values of 2000 μg/ml, being less active than standards antibiotics. Recently, the antimicrobial activity of Azorella cryptantha essential oil collected Argentinian Andean mountains was reported (Lima et al., 2011). The MIC values for Gram-negative bacteria reported in the present work were similar to those obtained for the other plant species traditionally used to treat ailments related to bacterial infections in the andean mountains of Argentina and collected between 2700 and 4800 m a.s.l. (Zampini et al., 2009; López et al., 2012).
| Bacteria | MIC of essential oils | |||
|---|---|---|---|---|
| A. trifurcata | S. pogonias | S. oreophyton | Cefotaxime | |
| Escherichia coli ATCC 25922 | 2000 | 2000 | 2000 | 0.5 |
| Escherichia coli-LM1 | 2000 | 2000 | 2000 | 5 |
| Escherichia coli 712 | >2000 | >2000 | >2000 | 0.05 |
| Escherichia coli 121 | >2000 | >2000 | 1500 | 1 |
| Escherichia coli 782 | >2000 | >2000 | >2000 | 1 |
| Enterobacter sp. | >2000 | >2000 | >2000 | 0.01 |
| Pseudomona sp. | 500 | >2000 | >2000 | 2.5 |
| Klebsiella pneumoniae ss. pneumoniae | >2000 | >2000 | >2000 | >12 |
| Staphylococcus, coagulase negative 968 | 1000 | >2000 | 1000 | 5 |
| Klebsiella pneumoniae ss. pneumoniae 94-1 | >2000 | >2000 | >2000 | >12 |
| Proteus mirabilis 94-2 | >2000 | >2000 | >2000 | 0.05 |
MIC: Minimum inhibitory concentration.
Food-borne illnesses associated with Gram (+) and Gram (−) bacteria such as E. coli, Staphylococcus aureus, Salmonella enteritidis, Listeria monocytogenes and Bacillus cereus present a major public health concern throughout the world.
The antimicrobial activity, against Gram negative and Gram positive bacteria of several Senecio spp. essential oil, including Senecio graveolens, S. aegyptius, S. subpanduratus Senecio mustersii, S. pandurifolius S. atacamensis were reported (Perez et al., 1999; El-Shazly et al., 2002; Arancibia et al., 2010; Benites et al., 2011; Kahriman et al., 2011). Components such as α-pinene, 1,8-cineole, γ-terpinene, linalool and α-terpineol have been found to have relatively strong antimicrobial properties (Bakkali et al., 2008). The EOs of the species A. trifurcata, S. oreophyton, and S. pogonias (Asteraceae) growing in locations in the central Andes (Argentina) showed a good antibacterial activity and support its medicinal uses.
Acknowledgements
The authors are grateful to CICITCA-UNSJ and SECITI Government of San Juan Province, Argentine for the financial support. S.L. and M.B.A. are doctoral students in PROBIOL-UNCuyo. B.L and M.B.A. hold a fellowship from CONICET. M.L.L., J.A.Z., G.E.F. are researchers from CONICET. To Servicio Nacional de Chagas for the T. infestans nymphs. Authors wish to thank Dra. M. Palacio for her help in the technical support in the GC–MS analysis.
References
- Identification of Essential Oil Components by Gas Chromatography/Mass Spectroscopy (4th ed.). Carol Stream, Illinois: Allured Publ. Corp.; 2007.
- Aromatic plants from Patagonia: chemical composition and antimicrobial activity of the essential oil of Senecio mustersii and S. subpanduratus. Bol. Latinoam. Caribe Plant. Med. Aromat.. 2010;9:123-126.
- [Google Scholar]
- Diterpenoids from Azorella madreporica and their antibacterial activity. Planta Med.. 2010;76:1749-1751.
- [Google Scholar]
- Biological effects of essential oils – A review. Food Chem. Toxicol.. 2008;46:446-475.
- [Google Scholar]
- Composition and antimicrobial screening of the essential oil from the leaves and stems of Senecio atacamensis Phil. from Chile. J. Chil. Chem. Soc.. 2011;56:712-714.
- [Google Scholar]
- The repellant and antifeedant activity of oil of Myrica gale against Aedes aegypti mosquitoes and its enhancement by the addition of salicyluric acid. J. R. Coll. Physicians Edinb.. 2003;33:209-214.
- [Google Scholar]
- Brooker, M.I.H., Kleinig, D.A., 2006. Field Guide to Eucalyptus. Melbourne: Bloomings. 3th ed. vol. 1. South-Eastern Australia.
- Ethnopharmaco botanical survey of Bauchaceta district, San Juan Province Argentina. Fitoterapia. 1996;5:411-415. LXVII
- [Google Scholar]
- Isolation and identification of mosquito bite deterrent terpenoids from leaves of American (Callicarpa americana) and Japanese (Callicarpa japonica) beautyberry. J. Agric. Food Chem.. 2005;53:5948-5953.
- [Google Scholar]
- Chemical compositions and larvicidal activities of leaf essential oils from two eucalyptus species. Bioresour. Technol.. 2009;100:452-456.
- [Google Scholar]
- In vitro spermatostatic activity of mulinane- and azorellane-type diterpenes on human spermatozoa. Lat. Am. J. Pharm.. 2011;30:1325-1329.
- [Google Scholar]
- Repellent activity of selected essential oils against Aedes aegypti. Fitoterapia. 2007;78:359-364.
- [Google Scholar]
- CLSI (Clinical and Laboratory Standards Institute), 2008. Performance Standards for Antimicrobial Susceptibility Testing. 8th Informational Supplement, Document M100-S18, Wayne, PA.
- Council of Europe (COE), 2005. European Directorate for the Quality of Medicines, in European Pharmacopeia. 5th ed. vol. 1, p. 217. Strasbourg.
- Chemical composition and biological activity of the essential oils of Senecio aegytius var. discoides Boiss. Z. Naturforsch.. 2002;57c:434-439.
- [Google Scholar]
- Free radical scavengers, anti-inflammatory and analgesic activity of Acaena magellanica. J. Pharm. Pharmacol.. 2002;54:835-844.
- [Google Scholar]
- Mosquito repellent activity of essential oils of aromatic plants growing in Argentina. Bioresour. Technol.. 2008;99:2507-2515.
- [Google Scholar]
- Development of environment-friendly insect repellents from the leaf oils of selected Malaysian Plants. Rev. Biodivers. Environ. Conserv. (ARBEC). 1998;6:1-7.
- [Google Scholar]
- Evaluation of extracts and oils of mosquito (Diptera: Culicidae) repellent plants from Sweden and Guinea-Bissau. J. Med. Entomol.. 2006;43:113-119.
- [Google Scholar]
- Chemical composition and antimicrobial activity of the essential oils from the flower, leaf, and stem of Senecio pandurifolius. Rec. Nat. Prod.. 2011;5:82-91.
- [Google Scholar]
- Essential oils of medicinal plants from the Central Andes of Argentina: chemical composition, and antifungal, antibacterial, and insect-repellent activities. Chem. Biodivers.. 2011;8:924-936.
- [Google Scholar]
- Essential Oil of Azorella cryptantha collected in two different locations from San Juan Province, Argentina: chemical variability and anti-insect and antimicrobial activities. Chem. Biodivers.. 2012;9:1452-1464.
- [Google Scholar]
- Azorellanol a diterpenoid with a new carbon skeleton from Azorella compacta. Tetrahedron. 1998;54:15533-15540.
- [Google Scholar]
- Epoxy-mulin-13-3n-20-oic acid, a diterpenoid from Azorella compacta. Phytochemistry. 1998;49:1091-1093.
- [Google Scholar]
- Diterpenoids from Azorella yareta and their trichonomicidal activities. Phytochemistry. 2001;56:177-180.
- [Google Scholar]
- Yaretol, a norditerpenoid from Azorella madreporica. J. Nat. Prod.. 2002;65:1678-1680.
- [Google Scholar]
- Mulinane-type diterpenoids from Azorella compacta display antiplasmodial activity. Phytochemistry. 2004;65:1931-1935.
- [Google Scholar]
- El género Azorella (Apiaceae-Hydrocotyloideae) en la Argentina. Darwiniana. 1989;29:139-178.
- [Google Scholar]
- Chemical composition and antimicrobial activity of the essential oils of Senecio rufinervis DC. (Asteraceae) IJNPR. 2011;2:44-47.
- [Google Scholar]
- Bioactive metabolites from the Andean flora. Antituberculosis activity of natural and semisynthetic azorellane and mulinane diterpenoids. Phytochem. Rev.. 2010;9:271-278.
- [Google Scholar]
- Monoterpenes from Thyme (Thymus vulgaris) as potential mosquito repellents. J. Am. Mosq. Control. 2005;21:80-83.
- [Google Scholar]
- The essential oil of Senecio graveolens (Compositae): Chemical composition and antimicrobial activity test. J. Ethnopharmacol.. 1999;66:91-96.
- [Google Scholar]
- Laboratory evaluation of toxic and repellent properties of the pithraj tree, Aphanamixis polystachya Wall & Parker, against Sitophilus oryzae (L) Int. J. Pest Manag.. 1994;40:274-279.
- [Google Scholar]
- Antibacterial diterpenoid acids from Azorella compacta. J. Nat. Prod.. 1999;62:1319-1321.
- [Google Scholar]
- WHO, 2014. www.who.int/zoonoses/en/.
- Repellency of aromatic medicinal plant extracts and a steam distillate to Aedes aegypti. J. Am. Mosq. Control. 2004;20:146-149.
- [Google Scholar]
- Antimicrobial activity of selected plant species from “the Argentine Puna” against sensitive and multi-resistant bacteria. J. Ethnopharmacol.. 2009;124:499-500.
- [Google Scholar]