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In this study seven strains of the genus Arthrobacter were screened by biotransformation to discover glycosylating patterns on steroid saponins. A strain of Arthrobacter nitroguajacolicus (CPCC 203516) was found to have the ability of fructosylation. Crude enzyme of the strain was extracted for the further study of conversion characteristics and patterns. Sucrose was used as a non-activated sugar donor, and fifteen steroidal saponins were involved. Nine furostan saponins of the substrates were converted, and ten products were isolated and identified. Based on the HR-ESI-MS, 1D, and 2D NMR spectral data, one fructosyl was added to furostan saponins at C6-OH of 26-O-β- d -glucopyranosyl by A. nitroguajacolicus for all nine products. One product was distinguished by an additional fructosyl at the position of C6-OH on the first added fructosyl. Spirostan saponins of the substrates could not be converted. Steroidal saponins embracing a fructosyl are quite rare according to other reports based on similar studies. This study successfully converted furostan saponins into new compounds.

Current production of diosgenin mainly depends on the acid hydrolysis of steroidal saponins from Dioscorea plants, and, in China especially, Dioscorea zingiberensis C. H. Wright (DZW) is used. The experimental results we obtained demonstrated that furostanol saponins, as the main constituents in DZW, were prone to generate 25-spirosta-3,5-diene as side product during the acid hydrolysis process, while spirostanol saponins hardly generated 25-spirosta-3,5-diene. This 25-spirosta-3,5-diene was the key reason leading to the low yield of diosgenin from DZW by acid hydrolysis. Effective conversion of furostanol saponins into spirostanol saponins can avoid the generation of 25-spirosta-3,5-diene so as to increase the yield of diosgenin, suggesting the importance of this preliminary conversion for improving the yield of diosgenin from DZW by acid hydrolysis. The conversion of furostanol saponins into spirostanol saponins can be performed by either enzymatic hydrolysis or spontaneous fermentation, whereas enzymatic hydrolysis is more controllable compared with spontaneous fermentation.

Sixteen steroidal saponins, including seven previously unreported compounds, were isolated from Tribulus terrestris. The structures of the saponins were established using 1D and 2D NMR spectroscopy, mass spectrometry, and chemical methods. They were identified as: 26-O-β-d-glucopyranosyl-(25R)-furost-4-en-2α,3β,22α,26-tetrol-12-one (terrestrinin C), 26-O-β-d-glucopyranosyl-(25R)-furost-4-en-22α,26-diol-3,12-dione (terrestrinin D), 26-O-β-d-glucopyranosyl-(25S)-furost-4-en-22α,26-diol-3,6,12-trione (terrestrinin E), 26-O-β-d-glucopyranosyl-(25R)-5α-furostan-3β,22α,26-triol-12-one (terrestrinin F), 26-O-β-d-glucopyranosyl-(25R)-furost-4-en-12β,22α,26-triol-3-one (terrestrinin G), 26-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl-(25R)-furost-4-en-22α,26-diol-3,12-dione (terrestrinin H), and 24-O-β-d-glucopyranosyl-(25S)-5α-spirostan-3β,24β-diol-12-one-3-O-β-d-glucopyranosyl-(1→4)-β-d-galactopyranoside (terrestrinin I). The isolated compounds were evaluated for their platelet aggregation activities. Three of the known saponins exhibited strong effects on the induction of platelet aggregation.

Three new oleanane-type triterpenoid saponins named celosins H (1), I (2), and J (3) were isolated from the seeds of Celosia argentea L. Their structures were characterized as 3-O-β-d-xylopyranosyl-(1 → 3)-β-d-glucuronopyranosyl-polygalagenin 28-O-β-d-glucopyranosyl ester, 3-O-β-d-glucuronopyranosyl-medicagenic acid 28-O-β-d-xylcopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-β-d-fucopyranosyl ester, and 3-O-β-d-glucuronopyranosyl-medicagenic acid 28-O-α-l-arabinopyranosyl-(1 → 3)-[β-d-xylcopyranosyl-(1 → 4)]-α-l-rhamnopyranosyl-(1 → 2)-β-d-fucopyranosyl ester by NMR, MS, and chemical evidences, respectively. In our opinion, celosins H–J could be used as chemical markers for the quality control of C. argentea seeds.

Twelve flavonoid glycosides were involved in the biotransformation of the glycosyl moieties by Curvularia lunata 3.4381, and the products were analyzed by UPLC/PDA-Q-TOF-MS(E). Curvularia lunata displayed hydrolyzing activities on the terminal Rha or Glc units of some flavonoid glycosides. Terminal Rha with a 1 → 2 linkage of isorhamnetin-3-O-neohesperidoside and typhaneoside could be hydrolyzed by Curvularia lunata, but terminal Rha with a 1 → 6 linkage of rutin, typhaneoside, and quercetin-3-O-apiosyl-(1 → 2)-[rhamnosyl-(1 → 6)]-glucoside could not be hydrolyzed. Curvularia lunata could also hydrolyze the Glc of icariin, floramanoside B, and naringin. This is the first report of the hydrolysis of glycosyl units of flavonoid glycosides by Curvularia lunata. A new way to convert naringin to naringenin was found in this research.

Two new kaurene diterpenoid glycosides, named Graecumoside A (1) and B (2), were isolated from fenugreek seeds, along with three known flavonoid-C-glycosides, isoorientin (3), isovitexin (4) and vitexin (5). By combined analyses of 1D- and 2D-NMR, and MS spectroscopy, the structures of two new compounds were elucidated as 3-O-β- D-glucopyranosyl kaur-5, 16-dien-3β, 6, 13β-trihydroxy-7-oxo-18-oic acid methyl ester and 3-O-β-neohesperidosyl kaur-5, 16-dien-3β, 6, 13β-trihydroxy-7-oxo-18-oic acid methyl ester, respectively. The kaurene diterpenoid glycosides were first isolated and identified from fenugreek seeds.

Eight novel steroidal saponins, ophiopogonins H-O (1-8), along with seven known steroidal saponins (9-15) were isolated from the tubers of Ophiopogon japonicus. The structures of these new compounds were determined by detailed spectroscopic analysis, including extensive 1D and 2D NMR data, and the analysis of hydrolytic reaction products. For the first time, rare furostanol saponins with disaccharide moiety linked at position C-26 of the aglycone were reported to be isolated from a natural source.

Five new glucosylated steroidal glycosides, cantalasaponin I-B1 (1), I-B2 (2), I-B3 (3), I-B4 (4) and I-B5 (5), were isolated and purified from the transformed product of the cantalasaponin I by using Toruzyme 3.0 l as biocatalyst. Their structures were elucidated on the basis of high-resolution electrospray ionization mass spectrometry, one-dimensional (1H and 13C NMR) and two-dimensional [COSY, heteronuclear single-quantum correlation (HSQC), HMBC and HSQC-TOCSY] NMR spectral analyses and chemical evidence. Copyright © 2012 John Wiley & Sons, Ltd.

A new furostanol saponin, sisalasaponin C (1), and a new spirostanol saponin, sisalasaponin D (2), were isolated from the fresh leaves of Agave sisalana, along with three other known steroidal saponins and two stilbenes. Their structures were identified as (3β,5α,6α,22α,25R)-3,26-bis[(β-D-glucopyrano- syl)oxy]-22-hydroxyfurostan-6-yl β-D-glucopyranoside (1), (3β,5α,25R)-12-oxospirostan-3-yl 6-deoxy-α-L-mannopyranosyl-(14)-β-D-glucopyranosyl-(13)-[β-D-xylopyranosyl-(13)-β-D-glucopyranosyl-(12)]-β-D-glucopyranosyl-(14)-β-D-galactopyranoside (2), (3β,5α,6α,22α,25R)-22-methoxyfurostane-3,6,26-triyl tris-β-D-glucopyranoside, cantalasaponin-1, polianthoside D, (E)- and (Z)-2,3,4′,5-tetrahydroxystilbene 2-O-β-D-glucopyranosides. The last three known compounds were isolated from the fresh leaves of Agavaceae for the first time. The structures of the new compounds were elucidated by detailed spectroscopic analysis, including 1D- and 2D-NMR experiments, and chemical techniques.

A mixture of a pair of stereoisomeric new spirostanol saponins (1a and 1b) and a new cholestane saponin (2) were isolated from the rhizome of Paris pollyphylla Smith var. yunnanensis. Their structures were elucidated as (25R)-spirost-5-en-3beta, 7beta-diol-3-O-alpha-L-arabinofuranosyl-(1 --> 4)-[alpha-L-rhamnopyranosyl-(1 --> 2)]-beta-D-glucopyranoside (1a), (25R)-spirost-5-en-3beta, 7alpha-diol-3-O-alpha-L-arabinofuranosyl-(1 --> 4)-[alpha-L-rhamnopyranosyl-(1 --> 2)]-beta-D-glucopyranoside (1b) and 26-O-beta-D-glucopyranosyl-(25R)-Delta(5(6), 17(20))-dien-16, 22-dione-cholestan-3beta, 26-diol-3-O-alpha-L-arabinofuranosyl-(1 --> 4)-[alpha-L-rhamnopyranosyl-(1 --> 2)]-beta-D-glucopyranoside (2) by a combination of HR-ESI-MS, FAB-MS, 1D and 2D NMR techniques (including (1)H-NMR, (13)C-NMR, (1)H--(1)H COSY, HSQC, HMBC and NOESY).

Two new steroidal saponins, timosaponin X (1) and timosaponin Y (2), and one new pregnane glycoside, timopregnane B (3), were isolated from the rhizomes of Anemarrhena asphodeloides, as well as three known compounds 25S-timosaponin BII (4), protodesgalactotigonin (5), and timosaponin BII-a (6) isolated from this plant for the first time. By the detailed analysis of 1D, 2D NMR, MS spectra, and chemical evidences, the structures of new compounds were elucidated as 26-O-β-d-glucopyranosyl-(25S)-5β-22-methoxy-furost-3β,26-diol 3-O-β-d-glucopyranosyl-(1 → 2)-α-l-arabinopyranoside (1), 5β-pseudo-spirost-3β,15α,23α-triol 3-O-β-d-glucopyranosyl-(1 → 2)-β-d-galactopyranoside (2), (5β,17α)-Δ((16)(17))-20-one-pregn-2β,3β-diol 3-O-β-d-glucopyranosyl-(1 → 2)-β-d-galactopyranoside (3).

Phytochemical investigation of the fresh tubers of Ophiopogon japonicus led to the isolation of two new furostanol saponins (1 and 2) together with two known steroidal saponins (3 and 4). Comprehensive spectroscopic analysis allowed the chemical structures of two new compounds to be elucidated as (25R)-26-O-[β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl]-5-ene-furost-1β,3β,22α,26-tetraol-3-O-α-l-rhamnopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 4)]-β-d-glucopyranoside (1, ophiopogonin P) and (25R)-26-O-[β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-5-ene-furost-1β,3β,22α,26-tetraol-3-O-α-l-rhamnopyranosyl-(1 → 2)-[β-d-xylopyranosyl-(1 → 4)]-β-d-glucopyranoside (2, ophiopogonin Q). Furostanol saponins with the disaccharide chain linked at C-26 hydroxy group of the aglycone have been rarely reported from natural sources.

Three new steroidal saponins, parisyunnanosides G-I (1-3), one new C(21) steroidal glycoside, parisyunnanoside J (4), and three known compounds, padelaoside B (5), pinnatasterone (6), and 20-hydroxyecdyson (7), were isolated from the rhizomes of Paris polyphylla Smith var. yunnanensis. Compounds 1 and 3 have unique trisdesmoside structures that include a C-21 β-d-galactopyranose moiety. All compounds were evaluated for their cytotoxicity against human CCRF leukemia cells.

Five new steroidal glycosides, timosaponin J ( 1), timosaponin K ( 2), (25 S)-karatavioside C ( 5), timosaponin L ( 6), and (25 S)-officinalisnin-I ( 8), together with eight known steroidal saponins, timosaponin E (1) ( 3), purpureagitosid ( 4), timosaponin BII ( 7), timosaponin B III ( 9), anemarrhenasaponin I ( 10), anemarrhenasaponin III ( 11), anemarrhenasaponin A (2) ( 12), and timosaponin A III ( 13), were isolated from the rhizomes of Anemarrhena asphodeloides. Their structures were elucidated on the basis of spectroscopic and chemical evidence. The aglycones of compounds 1 and 2 are new aglycones. Compounds 1- 13 were evaluated for their platelet aggregation activities, and compound 13 exhibited the strongest inhibitory effect on adenosine diphosphate (ADP)-induced platelet aggregation.

Four triterpenoid saponins were isolated from Albizziae cortex, and a complete assignment of their (1)H and (13)C NMR spectra was carried out using 1D and 2D NMR ((1)H-(1)H COSY, HSQC, HMBC, and HSQC-TOCSY) methods. Their (1)H NMR assignments were reported for the first time and some of their (13)C NMR spectral data reported in literature were corrected.