Isolation and identification of steroidal saponins in total saponin from Dioscorea nipponica Makino
To investigate the water-soluble steroidal saponins in total saponin from Dioscorea nipponica Makino and look for new active compounds.
The compounds were isolated with silica gel, PTLC and HPLC, and their structures were elucidated by acid hydrolysis, physical and chemical data and spectral analysis (IR, NMR, MS, HMQC, HMBC) as well as chemical correlations.
The two steroidal saponins (water-insoluble saponin and water-soluble saponin) were isolated from the total saponin of Dioscorea nipponica Makino. The structures were elucidated as diosgenin 3-O-[alpha-L-rhamnopy ranosyl (1-->2)-[beta-D-glucopyranosyl(1-->3)]]-beta-D-glucopyranoside (I), diosgenin 3-O-[alpha-L-rhamnopyranosyl (1-->3)-alpha-L-rhamnopyranosyl (1-->4)-alpha-L-rhamnopyranosyl (1-->4)]-beta-D-glucopyranoside (II).
Compound II is a new steroidal saponin and firstly isolated from Dioscorea nipponica Makino. It was named as dioscin Dc.
Available from: Zulfiqar Ali
- "D. nipponica Makino is also associated with antiobesity, antiinflammation, and anticancer properties . Previous studies of D. nipponica have reported the presence of steroidal glycosides    , phenanthrene derivatives  , water soluble non-saponin components [benzyl 1- O-β-D-glucopyranoside, leonuriside A, icariside D2, pyrocatechol 1-O-β-D-glucopyranoside, (+) syringaresinol-4-O-β-D-glucopyrano- side, cyclo-(leu-tyr), and adenosine , and a phenolic acid (piscidic acid) . In the present study, a phytochemical investigation of D. nipponica rhizomes was undertaken to discover new chemical constituents. "
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ABSTRACT: Nine glycosides of spirostan (1-7) and furostan (8 and 9) type steroids including a new compound, 7-oxodioscin (1), were isolated from the rhizomes of Dioscorea nipponica. The structure of 1 was established as (25R)-3beta-O-[(alpha-L-rhamnopyranosyl-(1 --> 4)-O-[alpha-L-rhamnopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl)oxy]spirost-5-en-7-one by extensive spectroscopic techniques including HRESI-TOFMS, 1D and 2D NMR, and chemical methods. Known compounds were elucidated as dioseptemloside G (2), (25R)-dracaenoside G (3), orbiculatoside B (4), dioscin (5), progenin III (6), gracillin (7), (3beta3,22alpha,25R)-26-(beta-D-glucopyranosyloxy)-22-methoxyfurost-5-en-3-yl O-[alpha-L-rhamnopyranosyl-(1 --4)]-beta-D-glucopyranoside (8), and methylprotodioscin (9).
Available from: Ming-Ju Hsieh
- "Previous studies have indicated that Dioscorea nipponica extract (DNE) could reduce the metastasis of melanoma in vitro and in vivo through inhibited phosphorylation of Akt, activation of NF-κB, and increase the expression of IκB . Furthermore, Du et al. have isolated and identified a new water-soluble steroidal saponin from Dioscorea nipponica Makino and defined its chemical structure (as shown in Figure 1(a)) . This newly isolated plant steroidal saponin is named dioscin. "
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ABSTRACT: Extensive research results support the application of herbal medicine or natural food as an augment during therapy for various cancers. However, the effect of dioscin on tumor cells autophagy has not been clearly clarified. In this study, the unique effects of dioscin on autophagy of hepatoma cells were investigated. Results found that dioscin induced caspase-3- and -9-dependent cell apoptosis in a dose-dependent manner. Moreover, inhibition of ERK1/2 phosphorylation significantly abolished the dioscin-induced apoptosis. In addition, dioscin triggered cell autophagy in early stages. With autophagy inhibitors to hinder the autophagy process, dioscin-induced cell apoptosis was significantly enhanced. An inhibition of caspase activation did not affect the dioscin-induced LC3-II protein expression. Based on the results, we believed that while apoptosis was blocked, dioscin-induced autophagy process also diminished in Huh7 cells. In conclusion, this study indicates that dioscin causes autophagy in Huh7 cells and suggests that dioscin has a cytoprotective effect.
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ABSTRACT: Yam–boxthorn noodle, a newly developed functional noodle, was prepared by mixing wheat flour, yam and boxthorn for the purpose of lowering serum cholesterol and oxidation status in vivo. To determine whether yam–boxthorn noodle exhibits hypolipidaemic and antioxidant effects in vivo, we examined the changes in triglyceride (TG), total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C) serum and oxidation levels in the serum and visceral organs of BALB/c females after continuously consuming the test diets for 5 weeks. The TG, TC, TG/HDL-C and TC/HDL-C serum levels in the experimental group decreased in a dose-dependent manner when the yam–boxthorn noodle concentration in the AIN 76 diet rose from 3 to 30%. However, the HDL-C and LDL-C serum levels did not significantly change. The TBARS oxidation index of the heart, liver and kidney significantly decreased compared with that of control group. The increase in tissue antioxidant capacity varied in magnitude: heart > liver > kidney. The total antioxidant status in the serum significantly increased in the 3% yam–boxthorn noodle diet experimental group. These experiments demonstrate that the functional noodle, yam–boxthorn noodle, exhibits hypolipidaemic and antioxidant effects in an in vivo murine model. Further, these results suggest that the functional ingredients in the yam and boxthorn, traditionally used as medicinal plants and functional foods, present greater health benefits than that of traditional noodles. These results will be important and useful for the future exploitation of traditional materials to develop a novel functional food for safeguarding health of hyperlipidaemia patients.
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