Silver complexation and tandem mass spectrometry for differentiation of triterpenoid saponins from the roots of Pulsatilla chinensis (Bunge) Regel.
For detection and differentiation of two types of triterpenoid saponins based on different aglycons of the lupane and oleanane skeleton from the roots of Pulsatilla chinensis (Bunge) Regel, the silver ion was introduced and electrospray ionization multi-stage tandem mass spectrometry was applied to analyze eleven triterpenoid saponin silver complexes. The quasi-molecular ion [M+Ag](+) was observed in the full-scan MS spectra of all the silver complexes. The MS(2) data of the [M+Ag](+) ion provided structural information on the sugar sequence of the oligosaccharide chains and the aglycon of the saponins. There are two patterns in the cleavage pathway of oleanane-type saponins. One is elimination of the sugar chain and subsequent loss of the carboxylic group which is the same as the cleavage of lupine-type saponins. The other is loss of the distinguishing ions at m/z 72 and 28 (C(2)H(4)) followed by loss of the carboxylic group. Diagnostic fragmentation pathways of the silver complexes of the saponins allow successful identification of the two types of saponins from the roots of Pulsatilla chinensis (Bunge) Regel.
Induction of the Phase II Enzyme, Quinone Reductase, by Withanolides and Norwithanolides from Solanaceous Species
The induction of the phase II drug-metabolizing enzyme, NAD(P)H:quinone reductase (QR), using Hepa 1c1c7 hepatoma cells, is currently used as a key member of a panel of in vitro bioassays in our program directed towards the discovery of new plant- derived cancer chemopreventive agents. Among a group of natural products, which have been studied as QR inducers are the withanolides, which constitutes about 400 C 28 ergostane-type steroids found mainly in approximately 10 genera of the plant family Solanaceae. New withanolides have been isolated and characterized in our recent work on Physalis philadelphica (tomatillo), which is used as a vegetable and condiment in Mexican and Central American cuisine. A further study on Deprea subtriflora has led to the discovery of a new class of C-18 norwithanolides with only 27 carbons in their skeleton. Preliminary structure-activity relationships have been determined for the in vitro induction of QR by members of the withanolide and norwithanolide classes.
Two new antifungal saponins from the Tibetan herbal medicine Clematis tangutica.
Bioassay-guided fractionation of the ethanol extract of the aerial parts of Clematis tangutica led to the isolation of two new antifungal triterpene saponins. Their structures were determined to be 3- O-alpha- L-arabinopyranosyl hederagenin 28- O-alpha- L-rhamnopyranosyl ester ( 1) and 3- O-beta- D-glucopyranosyl-(1--> 4)-alpha- L-arabinopyranosyl hederagenin 28- O-alpha- L-rhamnopyranosyl ester ( 2) on the basis of spectral data and chemical evidence. Inhibitory activities of the two saponins against seven fungal strains were evaluated. Compounds 1 and 2 showed evident antifungal activity (MIA approximately 2.5 micrograms/disc) against Saccharomyces cerevisiae, similar to the positive control amphotericin B and ordinary activities (MIA approximately 10 micrograms/disc) against Penicillium avellaneum UC-4376, Candida glabrata, Trichosporon beigelii and Pyricularia oryzae. Compound 2 is a better antifungal agent than compound 1 against most of the fungal strains that were tested.