Comparison of interactions between alpha-lactalbumin and three protopanaxadiol ginsenosides: Impacts on the structure and antitumor properties.

In this research, interactions between α-lactalbumin (ALA) and three protopanaxadiol ginsenosides [20(S)-Rg3, 20(S)-Rh2, and 20(S)-PPD] were compared to explore the effects of similar ligand on structure and cytotoxicity of ALA. Multi-spectroscopy revealed the binding between ALA and ginsenoside changed the conformation of ALA, which related to different structures and solubility of ligands. Scanning electron microscope illustrated that all ALA-ginsenoside complexes exhibited denser structures via hydrophobic interactions. Additionally, the cytotoxic experiments confirmed that the cytotoxicity of ginsenoside was enhanced after binding with ALA. Molecular docking showed all three ginsenosides were bound to the sulcus depression region of ALA via hydrogen bonding and hydrophobic interaction. Furthermore, molecular dynamics simulation elucidated the precise binding sites and pertinent system properties. Among all three composite systems, 20(S)-Rh2 had optimal binding affinity. These findings enhanced understanding of the synergistic utilization of ALA and ginsenosides as functional ingredients in food, medicine, and cosmetics.

[Protopanaxadiol-type ginsenoside hydrolases and their application in the preparation of ginsenoside Compound K: a review].

Ginsenoside Compound K (CK) has anti-cancer and anti-inflammatory pharmacological activities. It has not been isolated from natural ginseng and is mainly prepared by deglycosylation of protopanaxadiol. Compared with the traditional physicochemical preparation methods, the preparation of CK by hydrolysis with protopanaxadiol-type (PPD-type) ginsenoside hydrolases has the advantages of high specificity, environmental-friendliness, high efficiency and high stability. In this review, the PPD-type ginsenoside hydrolases were classified into three categories based on the differences in the glycosyl-linked carbon atoms of the hydrolase action. It was found that most of the hydrolases that could prepare CK were PPD-type ginsenoside hydrolase type Ⅲ. In addition, the applications of hydrolases in the preparation of CK were summarized and evaluated to facilitate large-scale preparation of CK and its development in the food and pharmaceutical industries.

Protopanaxadiol-type ginsenoside hydrolases and their application in the preparation of ginsenoside Compound K: a review / 生物工程学报

Ginsenoside Compound K (CK) has anti-cancer and anti-inflammatory pharmacological activities. It has not been isolated from natural ginseng and is mainly prepared by deglycosylation of protopanaxadiol. Compared with the traditional physicochemical preparation methods, the preparation of CK by hydrolysis with protopanaxadiol-type (PPD-type) ginsenoside hydrolases has the advantages of high specificity, environmental-friendliness, high efficiency and high stability. In this review, the PPD-type ginsenoside hydrolases were classified into three categories based on the differences in the glycosyl-linked carbon atoms of the hydrolase action. It was found that most of the hydrolases that could prepare CK were PPD-type ginsenoside hydrolase type Ⅲ. In addition, the applications of hydrolases in the preparation of CK were summarized and evaluated to facilitate large-scale preparation of CK and its development in the food and pharmaceutical industries.

Production of Prosaikogenin F, Prosaikogenin G, Saikogenin F and Saikogenin G by the Recombinant Enzymatic Hydrolysis of Saikosaponin and their Anti-Cancer Effect.

The saponins of Bupleurum falcatum L., saikosaponins, are the major components responsible for its pharmacological and biological activities. However, the anti-cancer effects of prosaikogenin and saikogenin, which are glycoside hydrolyzed saikosaponins, are still unknown due to its rarity in plants. In this study, we applied two recombinant glycoside hydrolases that exhibit glycoside cleavage activity with saikosaponins. The two enzymes, BglPm and BglLk, were cloned from Paenibacillus mucilaginosus and Lactobacillus koreensis, and exhibited good activity between 30-37 °C and pH 6.5-7.0. Saikosaponin A and D were purified and obtained from the crude B. falcatum L. extract using preparative high performance liquid chromatography technique. Saikosaponin A and D were converted into saikogenin F via prosaikogenin F, and saikogenin G via prosaikogenin G using enzyme transformation with high ß-glycosidase activity. The two saikogenin and two prosaikogenin compounds were purified using a silica column to obtain 78.1, 62.4, 8.3, and 7.5 mg of prosaikogenin F, prosaikogenin G, saikogenin F, and saikogenin G, respectively, each with 98% purity. The anti-cancer effect of the six highly purified saikosaponins was investigated in the human colon cancer cell line HCT 116. The results suggested that saikosaponins and prosaikogenins markedly inhibit the growth of the cancer cell line. Thus, this enzymatic technology could significantly improve the production of saponin metabolites of B. falcatum L.

Comparative study of steroidal sapogenins content in leaves of five Agave species.

BACKGROUND: Agaves are mainly used to produce alcoholic beverages such as tequila, mezcal and bacanora. However, the leaves constitute more than 50% of the plant and are not used in the production process, so they are considered waste. This plant material can be used as a source of bioactive compounds such as terpenes, flavonoids and saponins. Therefore, the objective of this study was to characterize the aglycone type of saponins and to quantify three steroidal sapogenins in leaves of five Agave species collected in different regions of Guerrero and Oaxaca, Mexico. RESULTS: Analysis by gas chromatography-flame ionization detection of the hydrolyzed methanolic extracts showed that diosgenin and tigogenin were the most abundant sapogenins identified in the five Agave species. Differences in the content of these sapogenins were found in the same species collected in different localities. The leaves of Agave americana var. oaxacensis L. (Oaxaca) had the highest diosgenin-derived saponin content, while the leaves of A. angustifolia Haw. (Guerrero) had the highest tigogenin-derived saponin content. Only in A. cupreata was sarsasapogenin identified, all three sapogenins occurring in the leaves of this species. For the first time, information is provided on the aglycones of the saponins produced in A. potatorum Zucc. and A. karwinskii Zucc. CONCLUSION: This study made it possible to compare the content of diosgenin and tigogenin-derived saponins in leaves of Agave species from Guerrero and Oaxaca. This information will be useful for better utilization of this plant material and add value to the process of mezcal elaboration. © 2022 Society of Chemical Industry.

Cycloastragenol alleviates airway inflammation in asthmatic mice by inhibiting autophagy.

Cycloastragenol (CAG), a secondary metabolite from the roots of Astragalus zahlbruckneri, has been reported to exert anti­inflammatory effects in heart, skin and liver diseases. However, its role in asthma remains unclear. The present study aimed to investigate the effect of CAG on airway inflammation in an ovalbumin (OVA)­induced mouse asthma model. The current study evaluated the lung function and levels of inflammation and autophagy via measurement of airway hyperresponsiveness (AHR), lung histology examination, inflammatory cytokine measurement and western blotting, amongst other techniques. The results demonstrated that CAG attenuated OVA­induced AHR in vivo. In addition, the total number of leukocytes and eosinophils, as well as the secretion of inflammatory cytokines, including interleukin (IL)­5, IL­13 and immunoglobulin E were diminished in bronchoalveolar lavage fluid of the OVA­induced murine asthma model. Histological analysis revealed that CAG suppressed inflammatory cell infiltration and goblet cell secretion. Notably, based on molecular docking simulation, CAG was demonstrated to bind to the active site of autophagy­related gene 4­microtubule­associated proteins light chain 3 complex, which explains the reduced autophagic flux in asthma caused by CAG. The expression levels of proteins associated with autophagy pathways were inhibited following treatment with CAG. Taken together, the results of the present study suggest that CAG exerts an anti­inflammatory effect in asthma, and its role may be associated with the inhibition of autophagy in lung cells.

Production of Minor Ginsenosides C-K and C-Y from Naturally Occurring Major Ginsenosides Using Crude ß-Glucosidase Preparation from Submerged Culture of Fomitella fraxinea.

Minor ginsenosides, such as compounds (C)-K and C-Y, possess relatively better bioactivity than those of naturally occurring major ginsenosides. Therefore, this study focused on the biotransformation of major ginsenosides into minor ginsenosides using crude ß-glucosidase preparation isolated from submerged liquid culture of Fomitella fraxinea (FFEP). FFEP was prepared by ammonium sulfate (30-80%) precipitation from submerged culture of F. fraxinea. FFEP was used to prepare minor ginsenosides from protopanaxadiol (PPD)-type ginsenoside (PPDG-F) or total ginsenoside fraction (TG-F). In addition, biotransformation of major ginsenosides into minor ginsenosides as affected by reaction time and pH were investigated by TLC and HPLC analyses, and the metabolites were also identified by UPLC/negative-ESI-Q-TOF-MS analysis. FFEP biotransformed ginsenosides Rb1 and Rc into C-K via the following pathways: Rd → F2 → C-K for Rb1 and both Rd → F2→ C-K and C-Mc1 → C-Mc → C-K for Rc, respectively, while C-Y is formed from Rb2 via C-O. FFEP can be applied to produce minor ginsenosides C-K and C-Y from PPDG-F or TG-F. To the best of our knowledge, this study is the first to report the production of C-K and C-Y from major ginsenosides by basidiomycete F. fraxinea.

Qualitatively and quantitatively investigating the metabolism of 20(S)-protopanaxadiol-type ginsenosides by gut microbiota of different species.

Ginsenosides Rb1, Rb2, Rb3 and Rc, four major protopanaxadiol (PPD)-type ginsenosides, can be metabolized by gut microbiota. The composition of gut microbiota varies in different species. Existing publications have reported the metabolite fates of ginsenosides by gut microbiota from single species. However, their microbiota-related metabolic species differences have not been evaluated yet. In current study, in vitro anaerobic incubations of PPD-type ginsenosides with gut microbiota from humans, rabbits and rats were conducted. The metabolites of each ginsenoside were then identified by LC-MS. A total of 15 metabolites from the four ginsenosides were identified. The major metabolic pathways were stepwise removals of the C-20 and C-3 sugar moieties to obtain aglycone PPD. The results showed that the hydrolysis rate of C-20 terminal ß-D-glucopyranosyl was significantly higher than those of α-L-arabinopyranosyl, ß-D-xylopyranosyl and α-L-arabinofuranosyl in different species. The activity of ß-glucosidase, the metabolic rates of parent compounds and the formation rates of their metabolites were significantly higher in gut microbiota from rabbits than from humans and rats. Our research draws researchers' attention to the species differences of microbiota-related drug metabolism.

Spirostanol Sapogenins and Saponins from Convallaria majalis L. Structural Characterization by 2D NMR, Theoretical GIAO DFT Calculations and Molecular Modeling.

Two new spirostanol sapogenins (5ß-spirost-25(27)-en-1ß,2ß,3ß,5ß-tetrol 3 and its 25,27-dihydro derivative, (25S)-spirostan-1ß,2ß,3ß,5ß-tetrol 4) and four new saponins were isolated from the roots and rhizomes of Convallaria majalis L. together with known sapogenins (isolated from Liliaceae): 5ß-spirost-25(27)-en-1ß,3ß-diol 1, (25S)-spirostan-1ß,3ß-diol 2, 5ß-spirost-25(27)-en-1ß,3ß,4ß,5ß-tetrol 5, (25S)-spirostan-1ß,3ß,4ß,5ß-tetrol 6, 5ß-spirost-25(27)-en-1ß,2ß,3ß,4ß,5ß-pentol 7 and (25S)-spirostan-1ß,2ß,3ß,4ß,5ß-pentol 8. New steroidal saponins were found to be pentahydroxy 5-O-glycosides; 5ß-spirost-25(27)-en-1ß,2ß,3ß,4ß,5ß-pentol 5-O-ß-galactopyranoside 9, 5ß-spirost-25(27)-en-1ß,2ß,3ß,4ß,5ß-pentol 5-O-ß-arabinonoside 11, 5ß-(25S)-spirostan-1ß,2ß,3ß,4ß,5ß-pentol 5-O-galactoside 10 and 5ß-(25S)-spirostan-1ß,2ß,3ß,4ß,5ß-pentol 5-O-arabinoside 12 were isolated for the first time. The structures of those compounds were determined by NMR spectroscopy, including 2D COSY, HMBC, HSQC, NOESY, ROESY experiments, theoretical calculations of shielding constants by GIAO DFT, and mass spectrometry (FAB/LSI HR MS). An attempt was made to test biological activity, particularly as potential chemotherapeutic agents, using in silico methods. A set of 12 compounds was docked to the PDB structures of HER2 receptor and tubulin. The results indicated that diols have a higher affinity to the analyzed targets than tetrols and pentols. Two compounds (25S)-spirosten-1ß,3ß-diol 1 and 5ß-spirost-25(27)-en-1ß,2ß,3ß,4ß,5ß-pentol 5-O-galactoside 9 were selected for further evaluation of biological activity.

Pyxinol bearing amino acid residues: Easily achievable and promising modulators of P-glycoprotein-mediated multidrug resistance.

The P-glycoprotein (Pgp) is a major transporter involved in multidrug resistance (MDR) of cancer cells leading to chemotherapy failure. In our previous study, we demonstrated that the amide derivatives of pyxinol are promising modulators against Pgp-mediated MDR in cancer. In the present study, we designed and synthesized novel pyxinol derivatives linked to amino acid residues. We evaluated MDR (paclitaxel (Ptx) resistance) reversal potency of forty pyxinol derivatives in KBV cells and analyzed their structure-activity relationships. Half of our derivatives sensitized KBV cells to Ptx at non-toxic concentrations, among which the pyxinol compound bearing a methionine residue (3c) exhibited the best activity in MDR reversal. Compound 3c was found to possess high selectivity toward Pgp and sensitize the KBV cells to Pgp substrates by blocking the efflux function of Pgp. This manifestation may be attributed to its high binding affinity with Pgp, as suggested by docking studies. Overall, the biological profile and ease of synthesizing these pyxinol derivatives render them promising lead compounds for further development for Pgp-mediated MDR.

Experimental and molecular docking investigation of the inclusion complexes between 20(S)-protopanaxatriol and four modified ß-cyclodextrins.

20(S)-Protopanaxatriol (PPT) is a type of ginsenoside isolated from panax notoginseng or ginseng, which is an essential ingredient in functional food, healthcare products and traditional medicine. However, the research and development of PPT are restricted due to its poor solubility. To circumvent the associated problems, a novel bridged-bis [6-(2,2'-(ethylenedioxy) bis (ethylamine))-6-deoxy-ß-CD] (H4) was successfully synthesized. The four inclusion complexes of the mono-[6-(1,4-butanediamine)-6-deoxy-ß-CD] (H1), mono-[6-(2,2'-(ethylenedioxy) bis (ethylamine)-6-deoxy-ß-CD] (H2) and their corresponding bridged bis(ß-CD)s (H3, H4) with PPT were prepared and studied by UV, 1H NMR, 2D ROESY, FT-IR, XRD and SEM technology. The UV-spectrometric titration showed that H1-4 and PPT formed 1:1 inclusion complexes and the binding constants were 297.61, 322.25, 937.88 and 1742 M-1, respectively. It was further revealed that the size/shape-matching relationship, hydrophobic interactions and hydrogen bond interactions play the crucial role in determining the stability of H1-4/PPT inclusion complexes. The solubility of PPT was evidently enhanced by193, 265, 453 and 593 times after the formation of inclusion complexes with H1-4, respectively. Furthermore, molecular docking was used to verify the inclusion mode of H4/PPT inclusion complex and also to investigate the stability of H4/PPT in water phase. The molecular simulation results agreed well with the experimental results. This research provides an effective way to obtain novel PPT-based functional food and healthcare products.

Telomerase activators from 20(27)-octanor-cycloastragenol via biotransformation by the fungal endophytes.

Cycloastragenol [20(R),24(S)-epoxy-3ß,6α,16ß,25-tetrahydroxycycloartane] (CA), the principle sapogenol of many cycloartane-type glycosides found in Astragalus genus, is currently the only natural product in the anti-aging market as telomerase activator. Here, we report biotransformation of 20(27)-octanor-cycloastragenol (1), a thermal degradation product of CA, using Astragalus species originated endophytic fungi, viz. Penicillium roseopurpureum, Alternaria eureka, Neosartorya hiratsukae and Camarosporium laburnicola. Fifteen new biotransformation products (2-16) were isolated, and their structures were established by NMR and HRESIMS. Endophytic fungi were found to be capable of performing hydroxylation, oxidation, ring cleavage-methyl migration, dehydrogenation and Baeyer-Villiger type oxidation reactions on the starting compound (1), which would be difficult to achieve by conventional synthetic methods. In addition, the ability of the metabolites to increase telomerase activation in Hekn cells was evaluated, which showed from 1.08 to 12.4-fold activation compared to the control cells treated with DMSO. Among the compounds tested, 10, 11 and 12 were found to be the most potent in terms of telomerase activation with 12.40-, 7.89- and 5.43-fold increase, respectively (at 0.1, 2 and 10 nM concentrations, respectively).

Anti-aging derivatives of cycloastragenol produced by biotransformation.

In this study, the microbial transformation of cycloastragenol (CA) by the fungi Mucor subtilissimus AS 3.2456 and Aspergillus oryzae AS 3.407 yielded 19 metabolites. Their structures were established based on extensive NMR and HR-MS data analyses, and six of them are new compounds. The two fungal strains exhibited distinct biocatalytic features. M. subtilissimus could catalyse hydroxylation and carbonylation reactions meanwhile the fragile 9,19-cyclopropane ring remained intact. A. oryzae preferred to catalyse hydroxylation, acetylation and ring expansion reactions. These highly specific reactions are difficult to achieve by chemical synthesis, particularly under mild conditions. Furthermore, we found that most of the metabolites could significantly extend the lifespan of Caenorhabditis elegans at 50 µM. These biotransformed derivatives of CA could be potential anti-aging agents.

Synthesis and anti-inflammatory activity of saponin derivatives of δ-oleanolic acid.

Pentacyclic triterpenes (PTs) are the active ingredients of many medicinal herbs and pharmaceutical formulations, and are well-known for their anti-inflammatory activity. On the other hand, anti-inflammatory effects of AMP-activated protein kinase (AMPK) have recently drawn much attention. In this study, we found that a variety of naturally occurring PTs sapogenins and saponins could stimulate the phosphorylation of AMPK, and identified δ-oleanolic acid (10) as a potent AMPK activator. Based on these findings, 23 saponin derivatives of δ-oleanolic acid were synthesized in order to find more potent anti-inflammatory agents with improved pharmacokinetic properties. The results of cellular assays showed that saponin 29 significantly inhibited LPS-induced secretion of pro-inflammatory factors TNF-α and IL-6 in THP1-derived macrophages. Preliminary mechanistic studies showed that 29 stimulated the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC). The bioavailability of 29 was significantly improved in comparison with its aglycon. More importantly, 29 showed significant anti-inflammatory and liver-protective effects in LPS/D-GalN-induced fulminant hepatic failure mice. Taken together, PTs saponins hold promise as therapeutic agents for inflammatory diseases.

Complete Bioconversion of Protopanaxadiol-Type Ginsenosides to Compound K by Extracellular Enzymes from the Isolated Strain Aspergillus tubingensis.

A compound K-producing fungus was isolated from meju (fermented soybean brick) and identified as the generally recognized as safe (GRAS) strain Aspergillus tubingensis. The extracellular enzymes obtained after the cultivation of 6 days in the medium with 20 g/L citrus pectin as an inducer showed the highest compound K-producing activity among the inducers tested. Under the optimized conditions of 0.05 mM MgSO4, 55 °C, pH 4.0, 13.4 mM protopanaxadiol (PPD)-type ginsenosides, and 11 mg/mL enzymes, the extracellular enzymes from A. tubingensis completely converted PPD-type ginsenosides in the ginseng extract to 13.4 mM (8.35 mg/mL) compound K after 20 h, with the highest concentration and productivity among the results reported so far. As far as we know, this is the first GRAS enzyme to completely convert all PPD-type ginsenosides to compound K.

Acid hydrolysis of saponins extracted in tincture.

BACKGROUND: Saponins are secondary metabolites from plants added to shampoos and beverages to make them foam, and the sapogenins released from them upon acid hydrolysis are commonly used as starting materials for steroidal drugs. However, current methods embed the saponin in a thick "gum" material consisting of multiple impurities. This gum limits access to the saponin, reducing the efficiency of hydrolysis and requiring large amounts of heat, organic solvents and effort to recover the sapogenin. For centuries, herbalists have been making tinctures by soaking plant materials at room temperature, in mixtures of alcohol and water. Many herbal tinctures contain saponins floating freely in solution, gum free. The saponin from sarsaparilla (Smilax spp), sarsasaponin, yields the sapogenin, sarsasapogenin, upon acid hydrolysis. The retail price of sarsasapogenin is very high but would be lower if the "gum problem" could be avoided. MATERIALS AND METHODS: We incubated sarsaparilla tincture under different conditions of temperature, acidity and duration then used quantitative nuclear magnetic resonance (qNMR) to measure the amount of sarsasapogenin produced by hydrolysis as well as the amount of its epimer, smilagenin. RESULTS AND DISCUSSION: Most, if not all the sarsasaponin in sarsaparilla root powder is extracted into a solution of 45% ethanol (55% water) at room temperature and stays suspended without formation of any particles (gum). Acid hydrolysis of the saponin in this solution is very efficient, approaching 100%. The sarsasapogenin released by hydrolysis and the smilagenin produced by its epimerisation, migrate into the chloroform phase. CONCLUSION: Sarsaparilla saponin diffuses into and disperses in a solution of alcohol:water (45:55) at room temperature. Hydrolysis of saponins in tincture provides a simple, inexpensive and environmentally friendly alternative.

Advance in glycosyltransferases, the important bioparts for production of diversified ginsenosides.

Ginsenosides are a series of glycosylated triterpenoids predominantly originated from Panax species with multiple pharmacological activities such as anti-aging, mediatory effect on the immune system and the nervous system. During the biosynthesis of ginsenosides, glycosyltransferases play essential roles by transferring various sugar moieties to the sapogenins in contributing to form structure and bioactivity diversified ginsenosides, which makes them important bioparts for synthetic biology-based production of these valuable ginsenosides. In this review, we summarized the functional elucidated glycosyltransferases responsible for ginsenoside biosynthesis, the advance in the protein engineering of UDP-glycosyltransferases (UGTs) and their application with the aim to provide in-depth understanding on ginsenoside-related UGTs for the production of rare ginsenosides applying synthetic biology-based microbial cell factories in the future.

New 20(S)-protopanaxadiol type saponins from the leaves of Panax notoginseng and their potential anti-inflammatory activities.

Through the combination of various chromatographies, 11 new 20(S)-protopanaxadiol (PPD) type saponins, named as notoginsenosides NL-E1 - NL-E4 (1-4), NL-F1 (5), NL-F2 (6), NL-G1 (7), NL-G2 (8), NL-H1 - NL-H3 (9-11) were obtained from the leaves of Panax notoginseng. Their structures were ascertained based on the extensive spectroscopic methods and chemical reactions. Meanwhile, the 20(S)-PPD type saponins with aglycone, (20S,24ζ)-3ß,12ß,20,24,25-pentahydroxy dammarane, was only found from the leaves of P. notoginseng. The characteristic could be used to distinguish the extracts of P. notoginseng leaves from its other medicinal parts such as roots, rhizomes, flowers or seeds. Furthermore, the nitric oxide (NO) inhibitory activities of all compounds were examined in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. As a result, compounds 2-7, 10 could exert NO inhibitory activity at 25 µM without cytotoxicity. Moreover, the inhibitory activities of them were in dose-dependent manner at 1, 10, and 25 µM. Especially, notoginsenoside NL-F2 (6) still possessed strong biological activity at 1 µM.

20S-Protopanaxatriol Ameliorates Hepatic Fibrosis, Potentially Involving FXR-Mediated Inflammatory Signaling Cascades.

Ginseng has been used as a functional food and tonic for enhancing immune power. Here, the potential protective effect of 20S-protopanaxatriol (M4), the metabolite of protopanaxatriol, against hepatic fibrosis is investigated, which could provide nutritional interventions for disease treatment. M4 could inhibit extracellular matrix (ECM) deposition and reduce the levels of proinflammatory cytokines such as caspase 1, interleukin 1 ß (IL-1ß), interleukin 1 receptor type 1 (IL1R1), and interleukin 6 (IL-6). M4 also significantly increased the expression of farnesoid X receptor (FXR), suppressed the purinergic ligand-gated ion channel 7 receptor (P2X7r) signaling pathway, and works as an FXR agonist, GW4064. In thioacetamide (TAA)-induced mice, M4 could attenuate the histopathological changes and significantly regulate the expression levels of FXR and P2X7r. M4 ameliorated TAA-induced hepatic fibrosis due to the reduction of P2X7r secretion, inhibition of hepatic stellate cell (HSCs) activation, and inflammation, which were all associated with FXR activation. Hence, M4 might be useful a nutritional preventive approach in antihepatic fibrosis and antihepatic inflammation.

Steroidal saponins and sapogenins from fenugreek and their inhibitory activity against α-glucosidase.

The seed of Trigonella foenum-graecum L. (fenugreek) has been reported to be rich in saponins, especially the dioscin or diosgenin, which are natural anti-diabetic agents with relatively low toxicity. Thus, the present study was to purify the saponins and sapogenins from fenugreek and to evaluate their α-glucosidase inhibitory activity in vitro. As a result, 33 steroidal saponins and sapogenins were isolated, including six undescribed ones and 27 previously known molecules. Among them, compounds 10, 12, 17, 22 and 29 were five 25R and 25S isomer mixtures of spirostanol saponins or sapogenins. The structures of compound 1-6 were established by 1D and 2D NMR spectroscopic analyses, high-resolution mass spectrometry, and chemical evidence. Compared to the positive control, sapogenins 26, 27, 14 and saponins 18 and 23 considerably inhibited α-glucosidase at IC50 values of 15.16, 8.98, 7.26, 5.49 and 14.01 µM, respectively. These results support the therapeutic potential of fenugreek in the treatment of diabetes with saponins and sapogenins as the active constituents.