Chemical constituents and antimicrobial activity of the aerial part of Solanum betaceum Cav. (Solanaceae).

A new saponin namely diosgeninoside (25 R-spirost-5-en-3-O-[ß-D-glucopyranosyl (1→2) - ß-D-glucuronic acid]) and a new fatty acid betacic acid: (Z)-8(S*),9(S*),10(R*)-trihydroxy-11-octadecenoic acid together with six known compounds: N-trans-coumaroyl tyramine, ergosta-7,22-dien-3ß,5α,6ß-triol, ß-sitosterol, and ß-sitosterol-3-O-ß-D-glucopyranoside, L-threitol and soya-cerebroside I were isolated from the methanolic extract of Solanum betaceum. The structures were elucidated by interpretation of their 1D and 2D NMR spectra and spectrometric data. The methanolic extract, the EtOAc and n-BuOH fractions, and several isolated compounds were tested for antibacterial activity against four bacteria (Staphylococcus aureus; Staphylococcus epidermidis; Escherichia coli; and Pseudomonas aeruginosa). The methanolic extract and the EtOAc fraction showed moderate activity against Staphylococcus aureus and Pseudomonas aeruginosa with MIC value of 128 µg/mL. Compound 1 showed moderate activity against Staphylococcus aureus with MIC value of 64 µg/mL.

Understory growth of Paris polyphylla accumulates a reservoir of secondary metabolites of plants.

Paris polyphylla is an important traditional medicinal plant of the Himalayan region. It is extensively used for the production of natural steroidal saponins and flavonoids. Although seed dormancy of wild plants can be broken to be artificially maintained and regenerated through micropropagation in the laboratory, the success of secondary metabolite production in higher quantities and the synthesis of superior plant metabolites have been very limited. In this study, we present differential metabolic profiling of P. polyphylla plants maintained for 8 years in natural and greenhouse conditions. Untargeted profiling of the metabolites through ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS), followed by statistical analysis, identified secondary metabolites that were enriched in the naturally occurring plant roots compared with the greenhouse plant roots. A multivariate statistical analysis revealed the differential distribution of the compounds between the two groups. Overall, we identified 1,182 secondary metabolites, with 116 metabolites being differentially upregulated and 256 metabolites being downregulated. Moreover, 810 metabolites showed no significant variation under both growing conditions. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that the naturally forest-grown P. polyphylla plants were significantly enriched in steroidal saponins, lipids, vitamins, flavonoids, and flavonols. An analysis of the top 10 differentially upregulated secondary metabolites indicated a significantly enriched quantity of spirost-5-en-3,12-diol and kaempferol synthesis pathways, which are known to reduce the effect of free radicals scavengers inside the cell. In addition, veratramine alkaloids were also enriched under natural conditions. Our findings indicated that naturally maintained P. polyphylla plants are suitable for the extraction of medicinally important compounds. Our study established a causal relationship between the metabolic composition of the roots and their natural growth condition. This study highlighted the importance of environmental conditions in the biosynthesis of secondary metabolites of plants.

Two New Steroidal Saponins with Potential Anti-Inflammatory Effects from the Aerial Parts of Gnetum formosum Markgr.

Gnetum formosum Markgr., a member of the Gnetaceae family, is distributed in Vietnam. This plant remains a botanical enigma with an unexplored diversity of chemical constituents and pharmacological effects. In this study, two new steroidal saponins, namely gnetumosides A (1) and B (2), were isolated from the aerial parts of G. formosum. Their chemical structures were elucidated using spectroscopic techniques, including high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and NMR, along with chemical hydrolysis and comparison with the reported literature. The potential anti-inflammatory effects of the isolated compounds were evaluated by measuring lipopolysaccharide-stimulated nitric oxide (NO) production in murine macrophage cells. Notably, compound 1 exhibited the most potent inhibitory activity (IC50 = 14.10 ± 0.75 µM), comparable to dexamethasone. Additionally, the mechanisms underlying the observed anti-inflammatory effects were investigated through molecular docking and molecular dynamics simulations on inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins. This study is the first to investigate the chemical constituents and pharmacological effects of G. formosum.

Ethnomedicinal Usage, Phytochemistry and Pharmacological Potential of Solanum surattense Burm. f.

Solanum surattense Burm. f. is a significant member of the Solanaceae family, and the Solanum genus is renowned for its traditional medicinal uses and bioactive potential. This systematic review adheres to PRISMA methodology, analyzing scientific publications between 1753 and 2023 from B-on, Google Scholar, PubMed, Science Direct, and Web of Science, aiming to provide comprehensive and updated information on the distribution, ethnomedicinal uses, chemical constituents, and pharmacological activities of S. surattense, highlighting its potential as a source of herbal drugs. Ethnomedicinally, this species is important to treat skin diseases, piles complications, and toothache. The fruit was found to be the most used part of this plant (25%), together with the whole plant (22%) used to treat different ailments, and its decoction was found to be the most preferable mode of herbal drug preparation. A total of 338 metabolites of various chemical classes were isolated from S. surattense, including 137 (40.53%) terpenoids, 56 (16.56%) phenol derivatives, and 52 (15.38%) lipids. Mixtures of different parts of this plant in water-ethanol have shown in vitro and/or in vivo antioxidant, anti-inflammatory, antimicrobial, anti-tumoral, hepatoprotective, and larvicidal activities. Among the metabolites, 51 were identified and biologically tested, presenting antioxidant, anti-inflammatory, and antitumoral as the most reported activities. Clinical trials in humans made with the whole plant extract showed its efficacy as an anti-asthmatic agent. Mostly steroidal alkaloids and triterpenoids, such as solamargine, solanidine, solasodine, solasonine, tomatidine, xanthosaponin A-B, dioscin, lupeol, and stigmasterol are biologically the most active metabolites with high potency that reflects the new and high potential of this species as a novel source of herbal medicines. More experimental studies and a deeper understanding of this plant must be conducted to ensure its use as a source of raw materials for pharmaceutical use.

Dereplication of Bioactive Agave Saponin Fractions: The Hidden Saponins.

The good phytotoxicity and selectivity against weeds versus tomato or cress make saponin-rich fractions from Agave macroacantha, A. colorata, A. parryi, and A. parrasana attractive candidates as bioherbicides. The saponin contents have only previously been reported for A. macroacantha, and as a consequence, simultaneous dereplication has been performed on saponin-rich fractions from the other plants by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. This strategy enables the identification of a total of 26 saponins, 14 of which have been described previously and 12 of which are proposed as new saponins. They include isomers and a new sugar chain with a ß-d-apiofuranose unit. The method is corroborated by the isolation of eight dereplicated saponins from A. colorata.

Arbuscular mycorrhiza and plant growth promoting endophytes facilitates accumulation of saponin under moderate drought stress.

Objective: Paris polyphylla var. yunnanensis, one of the important medicinal plant resources in Yunnan, China, usually takes 6-8 years to be harvested. Therefore, it is urgent to find a method that can not only shorten its growth years, but also improve its quality. In this study, we examined the effects of a combination treatment of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting endophytes (PGPE) and drought stress on the accumulation of saponins in it. Methods: P. polyphylla var. yunnanensis was infected with a mixture of AMF and PGPE under drought stress. The content of saponins, as well as morphological, physiological, and biochemical indicators, were all measured. The UGTs gene related to saponin synthesis was obtained from transcriptome data by homologous comparison, which were used for RT-PCR and phylogenetic analysis. Results: Regardless of water, AMF treatment could infect the roots of P. polyphylla var. yunnanensis, however double inoculation with AMF and PGPE (AMF + PGPE) would reduce the infection rate of AMF. Plant height, aboveground and underground fresh weight did not differ significantly between the single inoculation AMF and the double inoculation treatment under different water conditions, but the inoculation treatment significantly increased the plant height of P. polyphylla var. yunnanensis compared to the non-inoculation treatment. Single inoculation with AMF considerably increased the net photosynthetic rate, stomatal conductance, and transpiration rate of P. polyphylla var. yunnanensis leaves under various water conditions, but double inoculation with AMF + PGPE greatly increased the intercellular CO2 concentration and chlorophyll fluorescence parameter (Fv/Fm). Under diverse water treatments, single inoculation AMF had the highest proline content, whereas double inoculation AMF + PGPE may greatly improve the amount of abscisic acid (ABA) and indoleacetic acid (IAA) compared to normal water under moderate drought. Double inoculation AMF + PGPE treatment improved the proportion of N, P, and K in the rhizome of P. polyphylla var. yunnanensis under various water conditions. Under moderate drought stress, AMF + PGPE significantly enhanced the contents of P. polyphylla var. yunnanensis saponins I, II, VII, and total saponins as compared to normal water circumstances. Farnesyl diphosphate synthase (FPPS), Geranyl pyrophosphate synthase (GPPS), Cycloartenol synthase (CAS), and Squalene epoxidase (SE1) were the genes that were significantly up-regulated at the same time. The amount of saponins was favorably linked with the expression of CAS, GPPS, and SE1. Saponin VI content and glycosyl transferase (UGT) 010922 gene expression were found to be substantially associated, as was saponin II content and UGT010935 gene expression. Conclusion: Under moderate drought, AMF + PGPE was more conducive to the increase of hormone content, nutrient absorption, and total saponin content in P. polyphylla var. yunnanensis, and AMF + PGPE could up regulate the expression of key genes and UGTs genes in one or more steroidal saponin synthesis pathways to varying degrees, thereby stimulating the synthesis and accumulation of steroidal saponins in the rhizome of P. polyphylla var. yunnanensis. The combination of AMF and PGPE inoculation, as well as adequate soil drought, reduced the buildup of saponins in P. polyphylla var. yunnanensis and increased its quality.

DT-13 attenuates inflammation by inhibiting NLRP3-inflammasome related genes in RAW264.7 macrophages.

Plant derived saponins or other glycosides are widely used for their anti-inflammatory, antioxidant, and anti-viral properties in therapeutic medicine. In this study, we focus on understanding the function of the less known steroidal saponin from the roots of Liriope muscari L. H. Bailey - saponin C (also known as DT-13) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages in comparison to the well-known saponin ginsenoside Rk1 and anti-inflammatory drug dexamethasone. We proved that DT-13 reduces LPS-induced inflammation by inhibiting nitric oxide (NO) production, interleukin-6 (IL-6) release, cycloxygenase-2 (COX-2), tumour necrosis factor-alpha (TNF-α) gene expression, and nuclear factor kappa-B (NFκB) translocation into the nucleus. It also inhibits the inflammasome component NOD-like receptor family pyrin domain containing protein 3 (NLRP3) regulating the inflammasome activation. This was supported by the significant inhibition of caspase-1 and interleukin-1 beta (IL-1ß) expression and release. This study demonstrates the anti-inflammatory effect of saponins on LPS-stimulated macrophages. For the first time, an in vitro study shows the attenuating effect of DT-13 on NLRP3-inflammasome activation. In comparison to the existing anti-inflammatory drug, dexamethasone, and triterpenoid saponin Rk1, DT-13 more efficiently inhibits inflammation in the applied cell culture model. Therefore, DT-13 may serve as a lead compound for the development of new more effective anti-inflammatory drugs with minimised side effects.

Steroidal Saponins from Water Eggplant (Fruits of Solanum torvum) Exhibit Anti-Epileptic Activity against Pentylenetetrazole-Induced Seizure Model in Zebrafish.

The fruits of Solanum torvum Swartz, a wild relative of eggplant, are consumed as a wild vegetable in tropical regions of Africa, Asia, and South America. In traditional Chinese medicine, it is believed to have anti-inflammatory and sedative effects. In the Philippines, water decoction is used to treat hyperactivity disorder. Twenty-two steroidal saponins were isolated and purified from the fruits grown in Yunnan, China, including six new compounds: torvosides U-Z (1-6). During drying and cooking, the saponins may undergo transformation, resulting in small amounts of sapogenins. These transformations can include dehydration of hydroxyl groups at position C22, formation of double bonds at position 20, 22 or 22, 23, and even formation of peroxide products. Saponin compounds torvoside X (4), torvoside Y (5), torvoside A (7), and (25S)-3-oxo-5α-spirostan-6α-yl-O-ß-d-xylopyranoside (20), which are glycosylated at C-6, showed certain anti-epileptic activity in a pentylenetetrazole-induced zebrafish seizure model. No antiproliferative activity was detected when tested on the cancer cell line HepG2, and no hepatotoxic effect was noted on normal liver cell line LO2.

Antioxidant activity of spirostanol saponins from Allii Macrostemonis Bulbus and their contents in different origins and processed products.

Allii Macrostemonis Bulbus (AMB), a traditional Chinese edible and medicinal plant, is considered beneficial to health. In this study, we isolated and purified nine steroidal saponins (compounds 1-9) from AMB. Their structures were characterized using physicochemical properties, HR-ESI-MS, 1D and 2D NMR spectroscopy. Among these compounds, compounds 1-5 were newly discovered named macrostemonoside U-Y, respectively. We assessed the in vitro antioxidant properties of the nine steroidal saponins through free radical scavenging and reducing power assays. This provides options for developing natural antioxidants. Additionally, an HPLC-ELSD quantitative analysis method was developed for the nine saponins in 12 batches of AMB from different origins and processing methods. The results showed that the contents of the nine steroidal saponins in AMB varied greatly among different growing environments and processing methods.

Stigmastane-type steroid saponins from the leaves of Vernonia amygdalina and their α-glucosidase and xanthine oxidase inhibitory activities.

Two new vernonioside K (1) and vernonioside L (2) and four known Δ7,9(11) stigmastane-type steroidal saponins-vernonioside B2 (3), vernoniacum B (4), vernonioside B1 (5), and vernoamyoside A (6)-were isolated from the leaves of Vernonia amygdalina. Their structures were determined by comprehensive spectroscopic analysis with one-dimensional nuclear magnetic resonance, two-dimensional nuclear magnetic resonance, and high-resolution mass spectrometry. All isolated compounds (1-6) were evaluated to determine their inhibitory effects on α-glucosidase and xanthine oxidase. Among them, two new compounds 1 and 2 showed significant inhibition of α-glucosidase with IC50 values of 78.56 ± 7.28 and 14.74 ± 1.57 (µM), respectively, comparable with acarbose as a positive control (127.53 ± 1.73 µM); none of these compounds inhibited xanthine oxidase activity. Compounds 1 and 2 are promising candidates for the development of antidiabetic agents from natural sources.

Four Steroidal Saponins from the Trunks of Dracaena cambodiana with Inhibition of NO Production in LPS Activated RAW264.7 Cells.

Dracaena cambodiana Pierre ex Gagnep. is well known as a medicinal plant and widely distributed in Vietnam. Phytochemical investigation on the trunks of D. cambodiana lead to the isolation of four undescribed compounds (1-4) together with seven known ones (5-11). Their structures were determined to be pennogenin-24-yl-O-ß-D-glucopyranoside (1), 17α-hydroxycambodianoside C (2), (25R)-27-hydroxypenogenin 3-O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-glucopyranoside (3), (3ß,25R)-17α,22α-dihydroxy-furost-5-en-3-yl-O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-glucopyranoside (4), dracagenin A (5), 1-O-ß-D-glucopyranosyl-2-hydroxy-4-allylbenzene (6), 1-O-α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranosyl-2-hydroxy-allylbenzene (7), 2-O-α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranosyl-1-hydroxy-allylbenzene (8), cinnamrutinoside A (9), icariside D1 (10), and seco-isolariciresinol 9-O-ß-glucopyranoside (11) by extensive spectroscopic investigation, HR-ESI-MS, 1D and 2D NMR spectra. The anti-inflammatory activity of the isolated compounds was evaluated on macrophages. Compounds 1-6 significantly inhibited nitric oxide production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Among them, compound 1 showed the best inhibitory activity with an IC50 value of 8.90±0.56 µM.

Four New Steroidal Saponins from the Roots of Dracaena cambodiana with NO Production Inhibition Activity in LPS Activated RAW 264.7 Cells.

Seven steroidal saponins including three new 16,23-cyclocholestanes (1-3) and one new pregane (4) were isolated from the roots of Dracaena cambodiana Pierre ex Gagnep. Their chemical structures were elucidated to be (23R,25R)-26-O-ß-D-glucopyranosyl-16,23-cyclocholesta-5,17(20)-dien-22-one-3ß,16α,26-triol-3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→3)]-ß-D-glucopyranoside (1), (23R,25R)-26-O-ß-D-glucopyranosyl-16,23-cyclocholesta-5,17,20(22)-trien-3ß,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside (2), (23R,25R)-16,23-cyclocholesta-5,16,20(22)-trien-3ß,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside (3), 3ß-[(O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-gluco-pyranosyl)oxy]-pregna-5,17(20)-diene-16-one-20-carboxylic acid 4''''-O-ß-D-glucopyranosylisopentyl ester (4), cambodianoside A (5), diosbulbiside C (6), and diosbulbiside D (7), by IR, HR-ESI-MS, 1D and 2D NMR spectra. Compounds 1 and 4-7 inhibited nitric oxide (NO) production in lipopolysaccharide activated RAW 264.7 cells with IC50 values ranging from 19.03±1.84 to 67.92±3.81 µM, whereas compounds 2 and 3 were inactive with IC50 values over 100 µM.

Steroidal Saponins from Solanum lyratum Thunb.

Four undescribed steroidal compounds along with twenty known compounds were isolated from n-butanol extracted fraction of the whole plants of Solanum lyratum Thunb (SLNF). Their structures were assigned based on analyses of the extensive spectroscopic data (including MS, 1D/2D NMR, and ECD) or comparisons of the NMR data with those reported. Among the knowns, three compounds were isolated from Solanum plants for the first time, while one compound was isolated from S. lyratum for the first time. In addition, the cytotoxicities of these isolates against human colon SW480 and hepatoma Hep3B cells were evaluated by a MTT assay. And, nine of them and SLNF exhibited significant activities against both SW480 and Hep3B cells, while twelve of them significantly inhibited the activities of SW480 cells. This study allows for the exploitation of chemical markers with potential significance in discrimination of Solanum plants, and uncovers the diverse steroidal constituents from S. lyratum dedicated for its future application in cancer treatment.

Two New Compounds from Allii Macrostemonis Bulbus and Their In Vitro Antioxidant Activities.

Two new compounds named 4,4'-bis(ß-D-glucopyranosyloxy)biphenyl (1) and spirostane-25(27)-en-2α,3ß-diol-3-O-ß-D-xylopyranosyl(1→3)-ß-D-glucopyranosyl(1→4)-ß-D-galactopyranoside (2) were isolated from n-butanol extraction part of 80% ethanol extract of Allii Macrostemonis Bulbus. Alongside these, ten known compounds (3-12) were also identified, including a flavonoid glycoside (3), seven steroids (4-10), a nucleoside (11), and a phenylpropanoid glycoside (12) were found. Notably, compounds 3-6 were isolated from this plant for the first time. The structures of all compounds were confirmed using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1D, and 2D NMR spectroscopy. Some of these compounds showed strong antioxidant activity, and compound 1 demonstrated the most potent reduction of ferric ions (Fe3+) with an IC50 value of 0.59 ± 0.18 mg/mL. Compounds 2 and 3 exhibited the highest scavenging activity against superoxide anion radicals (O2-·) with an IC50 value of 0.02 ± 0.01 mg/mL. Additionally, compound 3 displayed substantial scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with IC50 values of 0.21 ± 0.17 mg/mL and 0.02 ± 0.01 mg/mL, respectively. The discovery of these two new compounds is a reference for identifying Allii Macrostemonis Bulbus quality markers. Moreover, their exceptional antioxidant activity offers a promising avenue for uncovering novel natural antioxidants.

In vitro production of steroidal saponin, total phenols and antioxidant activity in callus suspension culture of Paris polyphylla Smith: an important Himalayan medicinal plant.

Paris polyphylla Smith (Melanthiaceae) family, which is native to the Himalayan region, has received a lot of attention recently due to its extensive history of usage in traditional medicine. The production of steroidal saponin from callus suspension cultures of P. polyphylla was observed in the current study. The current study attempted to develop a P. polyphylla plant callus suspension culture through optimization of cultivation technique for callus suspension, quantification of total phenolic components and estimation of the extract's antioxidant activity. A light-yellow callus was formed within six weeks of cultivating rhizomes on Murashige and Skoog (MS) media supplemented with Thidiazuron (TDZ). Furthermore, the effect of TDZ, Methyl Jasmonate (MeJA), and Yeast Extract (YE) on callus growth, steroidal saponin (dioscin and diosgenin), total phenolic content, total flavonoids, total tannin, and total antioxidant activity was also measured. The medium containing 0.5 µM TDZ depicted the maximum callus biomass (2.98 g fresh weight). Significantly high phenolic and tannin content was observed in the MS medium containing 50 µM MeJA, whereas, no significant increase was observed in total tannin production in any treatment. Three in vitro assays, DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis (3-ethylbenzothiazoline- 6-sulfonic acid)) and FRAP (ferric ion reducing antioxidant potential) and FC (Folin-Ciocalteu), were used to assess antioxidant potential of callus. Maximum antioxidant analysis reported in 1.0 µM TDZ (6.89 mM AAE/100 g) containing medium followed by 50 µM MeJA (6.44 mM AAE/100 g). The HPLC analysis showed a high presence of dioscin and diosgenin (5.43% and 21.09%, respectively) compared to the wild sample (2.56% and 15.05%, respectively). According to the results, callus produced on media supplemented with 50 µM MeJA have significant phenolic contents and elevated antioxidant activity; nevertheless, callus growth was greater in the presence of 0.5 µM TDZ. The findings of the current study have commercial implications since greater biomass production will result in active phytochemicals that the pharmaceutical and nutraceutical sectors are in need desperately.

Deciphering the network of cholesterol biosynthesis in Paris polyphylla laid a base for efficient diosgenin production in plant chassis.

Cholesterol serves as a key precursor for many high-value chemicals such as plant-derived steroidal saponins and steroidal alkaloids, but a plant chassis for effective biosynthesis of high levels of cholesterol has not been established. Plant chassis have significant advantages over microbial chassis in terms of membrane protein expression, precursor supply, product tolerance, and regionalization synthesis. Here, using Agrobacterium tumefaciens-mediated transient expression technology, Nicotiana benthamiana, and a step-by-step screening approach, we identified nine enzymes (SSR1-3, SMO1-3, CPI-5, CYP51G, SMO2-2, C14-R-2, 8,7SI-4, C5-SD1, and 7-DR1-1) from the medicinal plant Paris polyphylla and established detailed biosynthetic routes from cycloartenol to cholesterol. Specfically, we optimized HMGR, a key gene of the mevalonate pathway, and co-expressed it with the PpOSC1 gene to achieve a high level of cycloartenol (28.79 mg/g dry weight, which is a sufficient amount of precursor for cholesterol biosynthesis) synthesis in the leaves of N. benthamiana. Subsequently, using a one-by-one elimination method we found that six of these enzymes (SSR1-3, SMO1-3, CPI-5, CYP51G, SMO2-2, and C5-SD1) were crucial for cholesterol production in N. benthamiana, and we establihed a high-efficiency cholesterol synthesis system with a yield of 5.63 mg/g dry weight. Using this strategy, we also discovered the biosynthetic metabolic network responsible for the synthesis of a common aglycon of steroidal saponin, diosgenin, using cholesterol as a substrate, obtaining a yield of 2.12 mg/g dry weight in N. benthamiana. Our study provides an effective strategy to characterize the metabolic pathways of medicinal plants that lack a system for in vivo functional verification, and also lays a foundation for the synthesis of active steroid saponins in plant chassis.

Screening and identification of lipase inhibitors extracted from Dioscorea nipponica Makino by UV-vis and HPLC coupled to UPLC-Q-TOF-MS/MS.

Dioscoreae nipponica Makino (D. nipponica) as the rhizome of dioscoreaceae rich in steroidal saponins, has been reported to have the hypolipidemic effects etc. However, it is still unclear which exact active components are primary responsible for the beneficial effects. This study was conducted to fish out the lipase inhibitors from D. nipponica, and evaluate the inhibitory activity on porcine pancreatic lipase (PPL) through in vitro kinetic assay using p-nitrophenyl palmitate as substrate. Accordingly, the ethanolic extract was subjected to D101 macroporous resin purification for spectrophotometric screening, high performance liquid chromatography (HPLC) separation and structural characterization by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Through orlistat validation, the PPL inhibitory activity and IC50 value of the extract were respectively 68.34 ± 1.47 % and 107.05 µg/mL under the optimized inhibition conditions. From 6 steroidal saponins identified, the inhibitory components named the protodioscin, protogracillin, dioscin and gracillin were fished out by grouping separation and HPLC analysis. Furthermore, dioscin and gracillin with the parent structure of diogenin were confirmed as the major inhibitors by virtue of stability tests based on transformation of protodioscin and protogracillin. Finally, the inhibitory mechanism of the major inhibitors toward PPL was further clarified by kinetic analysis and molecular docking analysis. The proposed method not only revealed the PPL inhibitory components in D. nipponica, but also provided an effective approach to hierarchical screening of PPL inhibitors from natural plants.

Polypunctosides E-K: seven new steroidal saponins from Polygonatum punctatum Royle ex Kunth and their nitric oxide production inhibitory activities.

Polygonatum punctatum Royle ex Kunth is a high-value medicinal plant found in old natural forests. A phytochemical study on the roots of this plant led to the isolation of seven new steroidal saponins including four furostans (1-4) and three furospirostans (5-7). Their structures were elucidated as (25R)-26-O-(ß-D-glucopyranosyl)-furost-5-ene-3ß,17α,22α,26-tetraol 3-O-α-L-arabinopyranosyl-(1 → 2)-ß-D-glucopyranosyl-(1 → 4)-ß-D-galactopyranoside (1), (25R)-26-O-(ß-D-glucopyranosyl)-furost-5-ene-3ß,14α,17α,22α,26-pentaol 3-O-α-L-arabinopyranosyl-(1 → 2)-ß-D-glucopyranosyl-(1 → 4)-ß-D-galactopyranoside (2), (25R)-26-O-(ß-D-glucopyranosyl)-furost-5-ene-22α-methoxy-3ß,17α,26-triol 3-O-α-L-arabinopyranosyl-(1 → 2)-ß-D-glucopyranosyl-(1 → 4)-ß-D-galactopyranoside (3), (25R)-26-O-(ß-D-glucopyranosyl)-furost-5-ene-22α-methoxy-3ß,17α,26-triol 3-O-[α-L-arabinopyranosyl-(1 → 2)-ß-D-glucopyranosyl-(1 → 4)]-[acetoxy-(→ 6)]-ß-D-galactopyranoside (4), 26-O-(ß-D-glucopyranosyl)-14α,17α-dihydroxynuatigenin 3-O-α-L-arabinopyranosyl-(1 → 2)-ß-D-glucopyranosyl-(1 → 4)-ß-D-galactopyranoside (5), 26-O-(ß-D-glucopyranosyl)-17α-hydroxynuatigenin 3-O-α-L-arabinopyranosyl-(1 → 2)-ß-D-glucopyranosyl-(1 → 4)-ß-D-galactopyranoside (6), and 26-O-(ß-D-glucopyranosyl)-14α-hydroxynuatigenin 3-O-α-L-arabinopyranosyl-(1 → 2)-ß-D-glucopyranosyl-(1 → 4)-ß-D-galactopyranoside (7) by extensive spectroscopic analyses, including infrared, high-resolution electrospray ionization mass spectrometry, and one- and two-dimensional nuclear magnetic resonance spectroscopy. Compounds 1-7 inhibited nitric oxide production in lipopolysaccharide activated RAW264.7 cells with IC50 values ranging from 41.5 ± 3.2 to 62.2 ± 3.7 µM, compared to 33.8 ± 2.6 µM for the positive control compound L-NMMA.

Conversion of Dioscorea zingiberensis saponins to prosapogenin A by enzymatic hydrolysis.

Prosapogenin A is a secondary saponin in Dioscorea zingiberensis, and it showed remarkable pharmacological effects. Due to very low content and lack of well-developed biotransformation, its preparation was not efficient and clean. This study aims to establish an eco-friendly strategy for preparation of Prosapogenin A from plant material. Physical separation was employed to recycle starch and cellulose, and then D101 resin and polyamide packed-bed column was incorporated for purification of total steroidal saponins (TSS). After these pretreatments, purity of TSS was largely increased to 83.2% with recovery at 87.6%, which was subjected to enzymatic hydrolysis. Optimized reaction system was constructed in 0.20 M HAc-NaAc buffer (pH4.2) containing cellulase/TSS (3:1, w/w), and the hydrolysis was performed at 53 °C for 6 h. Consequently, TSS was almost completely hydrolyzed to Prosapogenin A, while the highest yield reached 5.62%. The newly proposed approach is promising for efficient preparation of Prosapogenin A in industrial applications.

[Chemical constituents of Helleborus thibetanus].

The chemical constituents of Helleborus thibetanus were isolated and purified by silica gel column chromatography, Sephadex LH-20 gel column chromatography, and semi-preparative RP-HPLC, and the structures of all compounds were identified by modern spectrographic technology(MS, NMR). The MTT method was used to measure the cytotoxicity of compounds 1-8. Twelve compounds were isolated from the roots and rhizomes of H. thibetanus and were identified as(25R)-22ß,25-expoxy-26-[(O-ß-D-glucopyranosyl)oxy]-1ß,3ß-dihydroxyfurosta-5-en(1), ß-sitosterol myristate(2), ß-sitosterol lactate(3), ß-sitosterol 3-O-ß-D-glucopyrannoside(4), 4,6,8-trihydroxy-3,4-dihydronaphthalen-1(2H)-one(5), 1,3,5-trimethoxybenzene(6), 7,8-dimethylbenzo pteridine-2,4(1H,3H)-dione(7), 1H-indole-3-carboxylic acid(8), p-hydroxy cinnamic acid(9), lauric acid(10), n-butyl α-L-arabinofuranoside(11) and methyl-α-D-fructofuranoside(12), respectively. Among them, compound 1 is a new compound and named thibetanoside L; compounds 2, 5-8, 11 are first isolated from the family Ranunculaceae; compound 12 is isolated from the genus Helleborus for the first time. The results of MTT assay showed that the IC_(50) values of compounds 1-8 against HepG2 and HCT116 cells were greater than 100 µmol·L~(-1).