5.1 AEO and its volatile compounds

Since the Middle Ages, essential oil (EO) has been widely used in agriculture, food seasoning, cosmetics, and fragrance industries. With the development of modern pharmacology, EOs have also been widely used in the pharmaceutical and functional food industries. In nature, EOs have the function of plant protection, reducing the appetite of herbivores by scent to protect plant survival. In addition, EOs can attract animals and insects to pollinate plants and spread seeds, or repel unfriendly organisms that are harmful to plants (Bakkali et al., 2008). EOs are also often used as bacteriostatic agents, and many studies have collectively showed that their bacteriostatic function is by affecting the normal function of cell membranes, disrupting the stability of the lipid layer, affecting cellular energy metabolism and the reductase system (Da Costa Lima and de Souza, 2021; Rossi et al., 2022). At present, many volatile oil compounds have been isolated from A. tsao-ko, mainly including monoterpenes (1–34), oxygenated monoterpenes (35–95), sesquiterpenes (96–116), oxygenated sesquiterpenes (117–127), diterpenoids (128–131), aromatics (132–156), aliphatics (157–248), and ketones (249–264). Among them 1,8-cineole (70), α-citral (93), α-pinene (2), β-pinene (3), limonene (18), decanal (1 6 6), linalool (40), α-terpineol (41), geraniol (42), nerolidol (97) are the main chemical compounds.

5.2 Phenolics

Phenolics are important biologically active compounds, characterized by a phenolic structure (containing one or more hydroxyl groups on an aromatic ring), which can be divided into different groups according to the number of phenolic rings in the structure and the bonding elements between phenolic rings (Scalbert et al., 2005). It was of great significance in plant physiology and protection of plants from external aggression. At the same time, it also imparts a variety of biological activities to plants (Denny, 2007). The biological activity of phenolic compounds appears to be related to the presence and number of hydroxyl groups. Among them, the conjugation and resonance relationship had a great correlation with its antioxidant activity (Leopoldini et al., 2004). In recent years, a large number of phenolic compounds from A. tsao-ko were obtained by various extraction techniques (Li et al., 2017a; Shi et al., 2021;Wang et al., 2009).

5.3 Contains the chemical components of C6-C3-C6

Flavones are secondary metabolites which are widely present in plants and possess C6-C3-C6 as the basic carbon framework. It is extensively reported for exhibiting various biological properties. In recent years, researchers have isolated a large number of flavonoids from A. tsao-ko (Zhang et al., 2021; Kim et al., 2019a). Flavonoids are classified into various sub groups according to the substitution pattern of ring C. The oxidation state of the heterocyclic ring as well as the position of B ring are important in the classification as flavone glycosides (326–327), flavonoids (328–335), flavonoid (336–347), flavanone (348–362), chalcone and its derivatives (363–375).

5.4 Diarylheptanoids

Diarylheptanoids are an important bioactive compound in A. tsao-ko with a 2,6-epoxy pyran ring structure that inhibits α-glucosidase activity and has potential as a new antidiabetic drug candidate. 11 new and 13 known diarylheptanoids were isolated from the active part of A. tsao-ko under the guidance of bioassay. The enzyme kinetic study suggested that diarylheptanoids as the active constituents of A. tsao-ko with α-glucosidase inhibitory effects (He et al., 2020a). Thirteen new and four known 2,6-epoxydiarylheptanes were also isolated successively from A. tsao-ko, and 2,6-epoxydiarylheptane-like compounds were proposed as new antidiabetic drug candidates (He et al., 2020b).

5.5 Bicyclic nonane and steroids

Bicyclic nonane is a unique chemical in A.tsao-ko, a class of compounds with a bicyclic parent nucleus formed by a hexane ring and a pentane ring as the basic framework. One study isolated two bicyclic nonane from A. tsao-ko, both of which have inhibited LPS-induced NO production in BV2 microglial cells and are potential anti-inflammatory substances (Lee et al., 2008). Steroids are a class of compounds with the basic backbone structure of cyclopentane polyhydrophenanthrene as the parent nucleus, which usually bears two angular methyl groups and a side chain or oxygen-containing group containing a different number of carbon atoms. Qiu et al. (2012) analyzed and identified the active ingredients of A. tsao-ko by ultrasonic extraction combined with combined gas chromatography-mass spectrometry, and proved that A. tsao-ko contained steroidal compounds such as Stigmasterol and γ-Sitosterol. In addition, based on spectroscopic methods including MS, H-NMR, C-NMR, DEPT135, and HMQC spectroscopy, two more steroid compounds were isolated from A. tsao-ko (Zhang et al., 2014).

5.6 Flavanol-fatty alcohol hybrids and flavanol-menthane conjugates

19 new flavanol-fatty alcohol mixtures were isolated from A. tsao-ko for the first time and were named tsaokoflavanols A-S (434–452), in vivo experiments showed significant α-glucosidase and PTP1B inhibitory activities (He et al., 2020a). The following year, eight more rare flavanol-menthane-conjugates were isolated from A. tsao-ko and were named amomutsaokins A-H (453–460). It is interesting to note that compounds 453–456 are formed due to flavanol-menthane conjugates with the menthane part linked at the C-6 position of flavanol. Pharmacological studies have shown their inhibitory effect on three diabetes-related proteins (PTP1B, TCPTP and α--glucosidase) (He et al., 2021b).

5.7 Other compounds

According to the systematic pre-test study of phytochemical composition, A. tsao-ko also contains sugars, proteins, tannins, saponins, anthraquinones, coumarins, lactones, cardiac glycosides, steroids, oils, and anthocyanins in a variety of chemical compounds (Liu et al., 2011). According to research reports, A. tsao-ko is also rich in amino acids and mineral nutrients. An automatic amino acid analyzer was used to determine the content of 17 amino acids in A. tsao-ko, and the ICP method was used to determine the content of 9 mineral nutrients. It was found that the highest amino acid content was cereals and up to 3.01 g·kg⁻¹; Manganese content of the five trace elements was the highest and up to 822 mg·kg⁻¹ (Pu et al., 2015).

6.1 Regulate metabolic syndrome

Metabolic syndrome (MS) is one of the major medical and public health problems in the world. The main symptoms include complex metabolic disorders such as obesity, hyperglycemia, hypertension, and hyperlipidemia (Liu et al., 2023). Studies have shown that the active substances in CHM can reduce inflammation, resist oxidative stress, inhibit α-amylase and α-glucosidase, regulate intestinal flora, and inhibit the differentiation of preadipocytes (Li et al., 2023). A. tsao-ko as TCM, has the effect of regulating human metabolic syndrome. A large number of studies have shown that AEO, polyphenols, and flavonoids of A. tsao-ko are effective factors for regulating metabolism (He et al., 2021a, He et al., 2021b). This review summarises the research status of A. tsao-ko in regulating blood sugar and blood lipids, treating diabetes, and cardiovascular diseases (Fig. 5). In the future, it can be further studied for its potential medicinal value in other types of diseases, and promote the development of TCM health industry.

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Fig. 5

Pathway of active ingredients of A. tsao-ko in regulating metabolic syndrome.

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6.2 Anti-cancer

A study found that the methanolic extract of A. tsao-ko has cytotoxic activity, and diarylheptane compound 421 can be separated through the guidance of biological activity. Compound 421 had cytotoxicity against lung cancer A549 (IC₅₀ = 4.9 µg/mL) and melanoma SK-Mel-2 cells (IC₅₀ = 11.4 µg/mL), comparable to cisplatin (IC₅₀ = 7.4 and 10.0 µg/mL) (Moon et al., 2005). Furthermore, Yang et al. (2010) use of MTT method to study the AEO and its main bioactive substances (42 and 70) on human tumor cell lines (HepG2, Bel7402, Hela, A549, SGC-7901) and normal human cell lines (HL-7702, HUVEC) toxicity. By comparing with the anti-tumor drug mitomycin, it was found that the IC₅₀ value of AEO on all cancer cell lines was higher than that of mitomycin. AEO was less sensitive to the cytotoxicity of human normal cell lines HL-7702 (IC₅₀: 163.91 ± 5.11 ∼ 272.41 ± 0.97 µg/mL) and HUVEC (IC₅₀: 2.54 ± 0.13 ∼ 16.04 ± 0.04 µg/mL) (Yang et al., 2010). In addition, there are research reports, which use the MTT method to determine the chemical compounds in A. tsao-ko antiproliferative activities against HepG-2, SMMC-7721, Hela, and A549 human cancer cell lines. A. tsao-ko also has strong anti-tumor activity against HepG-2, SMMC-7721, Hela, and A549 cell lines (Zhang et al., 2015). Zhang and Yang (2015) established the H₂₂ tumor-bearing mice model to study the inhibitory effect of AEO on tumor cell growth. AEO could inhibit the proliferation of 6-10B cells in a dose-dependent manner, and its IC₅₀ for 24 h was 0.14 mg/mL. AEO can induce apoptosis by up-regulating the expression of Bax protein and down-regulating the expression of Bcl-2 protein, thereby achieving the effect of inhibiting the growth of tumor cells. Its pharmacological mechanism may be induced apoptosis of 6-10B cells through the mitochondrial apoptosis pathway, thereby exerting itself effectively (Gao et al., 2021). Moreover, EAT has been confirmed to have anti-ovarian cancer activity, and angiogenesis was a key factor in the growth of tumor cells (Pradeep et al., 2014). The inhibition rates of A. tsao-ko on SPHK1/2 enzyme activities were 59.75% and 22.75%, respectively, which could induce cell cycle arrest and apoptosis, exerting anticancer effects (Lee et al., 2019a). EAT did not influence vascular endothelial cells directly, but decreased IL-6 and VEGF secreted by ovarian cancer cells to inhibit angiogenesis through inhibition of p-STAT3 and NF-kB activation. And p-STAT3 and NF-kB could adjust each other and IL-6 and VEGF also mediates p-STAT3 and NF-kB too, which created a loop. EAT interrupted p-STAT3/NF-kB/IL-6 and VEGF loop through induced ER stress, achieving an anti-tumor effect (Chen et al., 2020).

6.3 Anti-inflammation

Inflammation is a harmful and irritating biological reaction triggered by the immune system due to pathogens, damaged cells, toxic compounds, and other factors, leading to acute or chronic inflammation in the body, which will cause pathological changes in the body (Chen et al., 2018; Medzhitov, 2010). Controlled inflammatory factors can be served as a defense mechanism for human health, but uncontrolled inflammatory factors can also lead to various inflammatory diseases in the human body (Zhou et al., 2016). In the studies of A. tsao-ko, researchers found that A. tsao-ko contains natural chemical compounds with good anti-inflammatory effects, including terpenoids and flavones. It has been reported that luteolin can induce the expression of OH-1 through Nrf₂ signaling to exert anti-inflammatory activity, thereby protecting body cells from various inflammatory factors (Akram et al., 2015). The extract and isolate of A. tsao-ko can effectively inhibit inductive nitric oxide synthase, it is of great significance for developing NO inhibitors to fight against inflammation (Mariotto et al., 2007). 2,8-decadiene-1,10-diol had anti-inflammatory activity in lipopolysaccharide-stimulated RAW 264.7 cells. 2,8-decadiene-1,10-diol can inhibit the production of NO by downregulating inducible NO synthase. Moreover, 2,8-decadiene-1,10-diol suppressed the production of pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-α. 2,8-decadiene-1,10-diol can inhibitory the expression of inflammatory proteins by mediated through the inactivation of mitogen-activated protein kinases (MAPKs), mainly extracellular signal-regulated kinase, c-Jun-N-terminal kinase, and p^38MAPK, and inhibition of nuclear factor-κB (NF-κB) pathways including degradation of inhibitor of κB-α and nuclear localization of NF-κB (Kim et al., 2016). In LPS-induced RAW 264.7 macrophages, the methanol extract of A. tsao-ko reduced the production of NO by inhibiting inducible NO synthase (iNOS) expression, and increased heme oxygenase-1 (HO-1) expression at the protein and mRNA levels (Shin et al., 2015). Compound 33 can inhibit the excessive production of NO-induced by lipopolysaccharide, thus achieving the purpose of inhibiting the expression of pro-inflammatory cytokines (Hong et al., 2021b). Compounds 373, 374, and 375 were obtained from A. tsao-ko, with a chalcone skeleton, which showed obviously inhibitory effects on the NO production with IC₅₀ values up to 22.5 μm (Kim et al., 2019b). In addition, compound 33 with the anti-inflammatory effect was exerted by inhibiting the NO production via down-regulation of iNOS in LPS-stimulated RAW264.7 cells (Hong et al., 2021b).

6.4 Anti-bacterial

At present, bacterial infection was the main source of infectious diseases. Bacteria have certain drug resistance, which may lead to the death of infected patients in severe cases (Stracy et al., 2022). The problem of bacterial resistance has become one of the major global health threats, so the development of new antibacterial agents has a very important role in medical research. The broad-spectrum inhibitory effect of A. tsao-ko on fungi, pathogenic bacteria, Gram-positive, Gram-negative bacteria, and Trichomonas vaginalis. The AEO exhibited moderate to potent broad-spectrum antimicrobial activity against 5 g-positive and 2 g-negative bacteria (MIC:2.94–5.86 mg/ml) (Cui et al., 2017). By intramuscular administration, AEO at the lowest effective dose of 0.92 g/kg/d protected mice from S. aureus or E. coli infection with a 100% survival rate (Dai et al., 2016a). The bacteriostatic mechanism of AEO to foodborne bacteria Escherichia coli may be through the change of permeability and integrity of cell membrane, resulting in leakage of nucleic acid and protein, MIC and MBC of 3.13 mg/mL and 6.25 mg/mL (Guo et al., 2017). In previous studied, compared with most of which exhibited intact genomic DNA, the cells cultured with AEO had numerous cells with condensed chromatin, significant nuclear fragmentation (Yang et al., 2010). In vitro, AEO had obvious anti-MRSA activity and had a synergistic effect and additive effect with other antibiotics, which can reverse the activity of MRSA against β-lactam antibiotics multidrug resistance. Xu et al. (2017) used the microfluidic method to determine the fractional inhibitory concentration (FIC) indexes of three kinds of β-lactam antibiotics (amoxicillin, cefalexin, and cefepime), AEO and three antibiotics synergy effects can reach 80%, and effectively enhances the therapeutic effect of antibiotics on MRSA. The extracts had anti-quorum (QS) sensing and anti-biofilm activities against gram-positive and gram-negative bacteria. Furthermore, the anti-QS activity of the A. tsao-ko extract (0.5–4 mg/ml) by using C. violaceum a biosensor strain and biofilm formation by crystal violate assay. It was found that minimum inhibitory concentration (MIC) for Staphylococcus aureus (Gram-positive), Salmonella Typhimurium, and Pseudomonas aeruginosa (Gram negative) were 1, and 2 mg/ml respectively (Rahman et al., 2017).

Trichomoniasis, caused by the flagellate protozoan Trichomonas vaginalis, is the most common non-viral sexually transmitted disease (STD) and is often treated with the drug 5-nitroimidazole. Over time, many strains of Trichomonas vaginalis have developed resistance to these therapeutic drugs (Osmari et al., 2020). Scientists found that AEO and compound 42, had a certain therapeutic effect on the strain. After the strain was treated with AEO and compound 42, the nuclear membrane was damaged, nuclei were dissolved, and the chromatin was accumulated; In the cytoplasm, numerous vacuoles appeared, rough endoplasmic reticulum dilated, the number of ribosomes was reduced, organelles disintegrated, the cell membrane was partially damaged, with cytoplasmic leakage, and cell disintegration was observed (Dai et al., 2015a). Furthermore, food-borne pathogens are a large group of bacteria that affect human health. Among them, Bacillus subtilis and Listeria monocytogenes have a greater impact on human health. Studies have found that A. tsao-ko extract can destroy the cell wall, cell morphology, and cell integrity of the two bacteria, thereby inhibiting the growth of Bacillus subtilis and Listeria monocytogenes (Tang et al., 2020). According to reports, A. tsao-ko also has good anti-pneumococcal activity (inhibition rate greater than 99%). The researchers tested the extract and isolates of A. tsao-ko for inhibitory activity against pneumonia, the MIC was 50 μg/mL, equal to the chloramphenicol positive control (Liu et al., 2018c). According to previous studies, the mechanism of the antibacterial activity of A. tsao-ko can be summarized into the following two aspects: On the one hand, it acts on the biofilm system of microbial cells, resulting in the destruction of the membrane structure and the increase in membrane permeability, resulting in the leakage of intracellular ions and contents; On the other hand, it acts on the enzyme system of microbial biochemical reactions, and the enzyme system is destroyed, resulting in cell death, thereby exerting bacteriostatic activity (Álvarez-Martínez et al., 2021). The broad-spectrum antibacterial activity of A. tsao-ko against microorganisms, especially pathogenic bacteria, makes A. tsao-ko a potential natural resource for the development of bacteriostatic agents and antibiotics, which also gives a hint to the probable mechanism of its clinical application such as foodborne and infectious diseases.

6.5 Antioxidation

Numerous studies have shown that cancer, arteriosclerosis or other diseases, and aging are all related to the production of excess free radicals (Martemucci et al., 2022). Antioxidants can effectively remove the free radicals generated by the human body due to continuous contact with the outside world, thereby avoiding the harm free radicals brings to the human body to the greatest extent (Sharma et al., 2018). Therefore, antioxidation is an important step in preventing diseases and resisting aging, and one of the important directions for the development of health and skincare products. A. tsao-ko has a very strong antioxidant capacity, mainly fat-soluble ingredients, of which catechin and their derivatives had a similar free radical scavenging ability to vitamin C (Yan, 2014). There are reports that catechin and catechol derivatives showed strong activities in both the DPPH radical scavenging activity and antioxidant activity assays. The study also explained that the difference in radical scavenging ability of Protocatechuic acid (2 6 5) and Protocatechualdehyde (3 2 2) may be because carboxyl groups can form intermolecular hydrogen bonds, while aldehyde groups cannot. Because of this bonding, the electron-with-drawing capacity of compound 265 is decreased, which leads to the weakening of its activity toward DPPH free radicals (Martin et al., 2000). In addition, AEO and their natural compounds have been extensively studied due to their strong aroma and strong antioxidant capacity (Ni et al., 2021). There are reports that AEO obtained from A. tsao-ko can be explored as a potent natural antimicrobial and antioxidant preservative ingredient in food industry. The IC₅₀ values of AEO determined by DPPH radical scavenging activity and β-carotene/linoleic acid bleaching assay were 5.27 and 0.63 mg/mL (Cui et al., 2017a). Ethanol (95%) extract and ethyl acetate extract of A. tsao-ko had significant DPPH free radical scavenging activity, and the compounds with antioxidant activity were mainly concentrated in ethyl acetate extract (Zhang et al., 2015). In addition, studies have shown that polyphenolic active substances isolated from A. tsao-ko have certain DPPH and ABTS free radical scavenging capabilities, with IC₅₀ values of 42.46 μg/mL and 85.47 μg/mL, respectively. And the concentration of polyphenols was positively correlated with its antioxidant activity (Li et al., 2017a). Studies have evaluated the antioxidant activities of 12 compounds, such as 3,4-dihydroxy benzoic acid and Meso-Hannokinol, which were isolated from A. tsao-ko. It was found that showed good DPPH radical scavenging activity in a dose-dependent manner. When the concentration was 100 μg/mL, 3,4-dihydroxy benzoic acid showed the best DPPH free radical scavenging activity, and its free radical scavenging rate was more than 90%, which was close to the DPPH free radical scavenging activity of vitamin C at the same concentration (Liu et al., 2018a). Methanol extracts of A. tsao-ko possessed high flavonoid content (1.21 mg QE/g DW), the results of in vitro experiments showed that A. tsao-ko has a strong oxygen-free radical absorption capacity, the ability to scavenge ABTS free radical antioxidants, and the iron reduction capacity (Zhang et al., 2021).

6.6 Neuroprotection

According to the research results of Zhang et al. (2014), flavonoids in A. tsao-ko have the biological activity of inhibiting H₂O₂-induced apoptosis of PC-12 cells. In this study, eight bioactive compounds were isolated from the A. tsao-ko, all of which had the effects of enhancing the viability of damaged PC-12 cells, of which quercetin had the most significant effect. In previous studies, it has also been shown that quercetin can effectively inhibit the biological activity of the iNOS/NO system and adrenocorticotropic hormone, thereby exerting neuroprotective effects (Zhang et al., 2011). A. tsao-ko has chemicals that protect against nerve damage caused by exogenous drugs, GG-A and GG-B could protect the PC-12 cells against H₂O₂ induced injury by reversing the H₂O₂ induced cells viability loss, and their protective effects were close to that of VC (50 μg/mL) (Zhang et al., 2016). After treatment with compounds GG-A and GG-B the decreasing trend of H₂O₂-induced cell viability was inhibited in a dose-dependent manner, and the researchers also found that GG-B showed higher activity in enhancing the cell viability. In addition, some studies have shown that A. tsao-ko has anti-epileptic biological activity. Its ethanolic extract significantly reduced the time and duration of seizures in PTZ animals (Wang et al., 2021c). Gao et al. (2018) used Tsaoko-Anemarrhenae decoction to study epileptic rats (SPF grade SD male rats) models, the anti-epileptic mechanism of Tsaoko-Anemarrhenae decoction was discussed from the perspective of miRNA regulation. The mechanism was to down-regulate the expression of miR-29 and up-regulate the expression of miR-21 to target and regulate the expression of apoptosis-related genes Bax, P53, and Bcl-2, inhibit cell apoptosis and play an anti-epileptic effect.

6.7 Regulate gastrointestinal function

In China, in addition to being used as condiments and spices, A. tsao-ko used as a traditional medicine for the treatment of digestive diseases and infectious diseases. The researchers obtained a lot of inspiration from the classical Chinese prescriptions, combined with the characteristics of modern pharmacology, improved the prescriptions, and obtained good clinical effects in the treatment of diseases. In traditional medicine, A. tsao-ko is often used in TCM to treat abdominal pain and diarrhea. According to this principle, Dai, (2003) used A. tsao-ko to treat 42 patients with abdominal distension after cesarean section and found that the effective rate of the treatment could reach 92.7%, which showed the effect of A. tsao-ko postpartum abdominal distension to promote gastrointestinal gas, and the fruit has no toxic side effects and can be widely used in postpartum women with abdominal distension. Yang, (2011) studied the effects of the volatile oil of A. tsao-ko on gastric emptying and intestinal propulsion in mice. The results showed that volatile oil of A. tsao-ko could significantly or inhibit promote the gastric emptying ability of mice. The intestinal peristalsis of the mouse indicates that AEO has a significant inhibitory effect on intestinal propulsion. At the same time, with the increase of the dose, the inhibitory effect of AEO on intestinal propulsion also increases. A study showed that the water extract of A. tsao-ko could promote the peristalsis of the small intestine of constipated mice, and effectively improve the symptoms of constipation in mice (Yang et al., 2020). Recently, studies have used GC–MS combined with network pharmacological analysis to construct a component-target pathway network, revealing that there are 12 compounds in A. tsao-ko that play a potentially critical role in the treatment of dyspepsia. And through KEGG enrichment analysis of 17 signal pathways, the results show that the signal pathway of regulation of lipolysis (hsa04923) and serotonergic synapse (hsa04726) play an important role in the treatment of dyspepsia.

In summary, the mechanism of A. tsao-ko in the treatment of dyspepsia may be related to a variety of compounds, target genes, and signal pathways (Shi et al., 2021). In regulating gastrointestinal function, oral decoction has low production cost, significant curative effect, and no toxic side effects have been found, so it can be clinically promoted. However, its functional mechanism is still unclear, and its physiological regulation mechanism can be explored through the results of these clinical applications and in vivo experimental results combined with modern pharmacological research.

6.8 Other pharmacological properties

A. tsao-ko also has anti-allergic active ingredients. Studies have shown that EAT (80%) contain the compounds helichrysetin and cardamomin, and the inhibitory rate of β-hexosaminidase released by RBL-2H3 cells at a concentration of 50 μM is 99.1% and 21.3%, indicating that A. tsao-ko has threshing inhibitory effect and has the potential to be used as a natural anti-allergic drug (Shim et al., 2021a). In addition, the ethanolic extract of A. tsao-ko can significantly prevent ovx-induced deterioration of bone mineral density and trabecular tissue microstructure, and significantly inhibit osteoclast differentiation by down-regulating the osteoclast NF-κB/Fos/NFATC1 signaling pathway (Shim et al., 2021). A. tsao-ko was reported that volatile oil extracted by steam distillation and then separated by separation technology had toxic effects on Triboliumcastaneum (Herbst) and Lasiodermaserricorne (Fabricius). The exposure toxicity results showed that were considered together, suggest that the AEO and the two compounds show potential to be developed as natural insecticides/fumigants for control of stored product insects (Wang et al., 2014). Furthermore, polyphenolic and AEO can alleviate hypercholesterolemia in hamsters through the interaction of gut flora (mainly Ruminococcaceae) and bile acid metabolism at the population level. The mechanism may be to improve hypercholesterolemia by increasing the production of short-chain fatty acids, which increases the mutual communication between the intestinal flora and host cells, inhibited the activity of HMG-CoA-R (Liu et al., 2021).

7.1 Origin identification

As we all know, the material basis of CHM is different chemical compounds, especially the secondary metabolites of plants. Different growth environments will produce different secondary metabolites, resulting in differences in quality. The geographic origin of the fruit directly affects its flavor and medicinal effects of A. tsao-ko. A. tsao-ko originates from different regions, and its component is bound to be different. Among modern regulatory techniques, chromatography and its combined techniques have been successfully used to assess the quality of botanical drugs from different geographic sources. However, the pharmacological effect of A. tsao-ko is the result of the multi-component synergistic effect among its chemical compounds. Therefore, the overall efficacy of A. tsao-ko cannot be evaluated if only the labeled compounds are considered (Huang et al., 2018). In recent years, spectroscopy technology has been widely used in the identification of CHM, with the advantages of low cost, green, non-destructive and fast analysis (Liu et al., 2020; Pei et al., 2019; Wang et al., 2021a). Studies have shown that the use of infrared spectroscopy and ultraviolet–visible spectroscopy, combined with chemometrics and data fusion strategies, can effectively identify the geographic origin of A. tsao-ko ((Liu et al., 2021). The application of spectral technology provides a fast and nondestructive means for the geographic traceability of A. tsao-ko, and provides a theoretical basis for the establishment of A. tsao-ko quality evaluation system.

7.2 Variety identification

In recent years, two varieties of yellow-flowered fruit (A. tsao-ko) and white-flowered fruit (Amomum paratsao-ko) have been discovered in the planting area of Yunnan Province (Qin et al., 2021). Both A. tsao-ko and Amomum paratsao-ko belong to the genus Amomum Roxb in the Zingiberaceae. The fruits are similar in shape and used. The traditional method of observing the macroscopic characteristics is difficult to distinguish, so during the harvest period, they are often mixed. Luo, (2014) used traits and microscopic identification to identify the two varieties. However, regardless of trait identification or microscopic identification, the characteristics are very similar and it is difficult to distinguish. Huang et al. (2014) used GC–MS to study the volatile oil compounds of the two varieties. Although the morphological characteristics of the two varieties are similar, the chemical substances and content contained in them are very different, so the two varieties must be identified. For a long time, the data fusion strategy of vibrational spectroscopy combined with chemometric methods is often used in the identification of CHMs (Li and Wang, 2018; Wang et al., 2020). Qin et al. (2021) combined GC–MS or NIR with multivariate analysis to develop a discriminatory model, the classification accuracy rate is 100%. The identification method solves the problem that it is difficult to distinguish the two species, and provides a reference for distinguishing A. tsao-ko from its conformis. This study provides a theoretical basis for the identification of specificity between A. tsao-ko and its related species.

8.1 Applications and market dynamics

The main uses of A.tsao-ko were in the food industry, where it was used as food additives for more than 90% of the time and as Chinese patent medicine for less than 5%. As a flavoring and aromatizing agent, A.tsao-ko is commonly used in the food industry, mainly in dried fruits, powders, and flavorings (Zhang et al., 2014). There are many types of Chinese patent medicines with CHM compatibility, such as tou gu sou feng wan, yi shen wan, kai yu shu gan wan, kuan xion li ge wan, jie bai wan (Pu et al., 2015) (Fig. 6). Furthermore, although fewer products are commercially available, A.tsao-ko is used in the cosmetic industry. There is considerable potential for sun protection products based on AEO, since they have a good UV absorption effect, making them suitable for perfumery and skin care products.

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Fig. 6

Example of the application of A.tsao-ko (Image material from https://cn.bing.com/.).

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Considering A. tsao-ko unique characteristics, the price is in a stable phase, according to the survey. Due to its distinctive aroma, A. tsao-ko has an important position in the flavoring market. Meanwhile, A. tsao-ko is a traditional CHM in Southeast Asia and is in steady demand, albeit in smaller quantities. The price of A. tsao-ko has remained relatively stable since 2016. In 2017, the price of A. tsao-ko rose suddenly as a result of a drought and a snow and ice disaster in 2016. There is a fourfold increase in price in July compared to expected. As new stock appeared in August, the price of A. tsao-ko gradually decreased until September 2018, when it leveled off. There was no significant fluctuation in A. tsao-ko’s price following this period. Recently, there has been a gradual decline in the price, possibly due to the policy of vigorous A. tsao-ko cultivation (Figure S1).

8.2 The economic value of cultivating

At present, A. tsao-ko of China’s market is in short supply and must be imported from Vietnam, Myanmar, and other countries, and imports are increasing. Its cultivation has the advantages of low investment (30,000–45,000 yuan/hm²⁾, quick results (4 to 5 years for flowering and fruiting), long benefit time (up to 20 years), and high economic value. It is poverty alleviation in China's southwest border region. The pillar industry to tackle tough problems (Liu et al., 2017; Zhang et al., 2011). A survey showed that as of 2018, the total output value of A. tsao-ko reached 350 million, the national annual consumption of A. tsao-ko and dried fruit was about 12,550 tons, and the world’s total output of A. tsao-ko and dried fruit was about 12,550 tons, showing a market situation in short supply. Nujiang prefecture regards A. tsao-ko as a core industry to help peasants increase their income, helping the poor to increase their income per capita by more than 2,700 yuan (Liu et al., 2021). In addition, Vietnam is also one of the main producers of the international market of A. tsao-ko, which is of great significance for the Vietnamese people to get rid of poverty and become rich.

In summary, the cultivation of A. tsao-ko is of great significance, and the development of spice and TCM cultivation can increase the income of the western provinces of China and promote economic development. Regrettably, due to the high price in recent years, the planting volume of A. tsao-ko has increased greatly, coupled with the lack of planting and production standards, research on variety selection, planting technology, processing methods, and insect control technology has led to product quality varies. Therefore, it is necessary to explore effective management mechanisms and production standards.