Dean Guo

Triterpenoidal saponins from Gleditsia sinensis

Six bisdesmosidic triterpenoidal saponins, gleditsiosides H-K and gleditsia saponins C and E, were isolated from the anomalous fruits of Gleditsia sinensis. Their structures were established by a combination of extensive NMR (DEPT, DQF-COSY, HETCOR, HOHAHA, HMBC and ROESY) studies and chemical degradation.

Anthraquinones from hairy root cultures of Cassia obtusifolia

Hairy root cultures of Cassia obtusifolia clones transformed with Agrobacterium rhizogenes strain 9402 were established to investigate the anthraquinone production. Seven anthraquinones, together with betulinic acid, stigmasterol and sitosterol were isolated from the hairy roots. Their chemical structures were elucidated on the basis of chromatographic and spectral data. The effects of culture conditions and rare earth element Eu(3+) on the production of six free anthraquinones have also been investigated. It was found that changes of the elements in the culture medium and addition of rare earth element Eu(3+) can greatly influence the contents of free anthraquinones in the hairy roots.

Gaultherins A and B, two lignans from Gaultheria yunnanensis

Abstract Two lignans, trivially named gaultherins A ( 1 ) and B ( 2 ), were isolated from the roots of Gaultheria yunnanensis (Ericaceae). Their structures were deduced as 5-methoxy-(+)-isolariciresinol-9,9′-diacetate ( 1 ) and (+)-lyoniresinol-9,9′-diacetate ( 2 ), based upon physicochemical properties, spectral analyses and chemical degradation.

Identification of Key Licorice Constituents Which Interact with Cytochrome P450: Evaluation by LC/MS/MS Cocktail Assay and Metabolic Profiling

Licorice has been shown to affect the activities of several cytochrome P450 enzymes. This study aims to identify the key constituents in licorice which may affect these activities. Bioactivity assay was combined with metabolic profiling to identify these compounds in several complex licorice extracts. Firstly, the inhibition potencies of 40 pure licorice compounds were tested using an liquid chromatography/tandem mass spectrometry cocktail method. Significant inhibitors of human P450 isozymes 1A2, 2C9, 2C19, 2D6, and 3A4 were then selected for examination of their structural features by molecular docking to determine their molecular interaction with several P450 isozymes. Based on the present in vitro inhibition findings, along with our previous in vivo metabolic studies and the prevalence of individual compounds in licorice extract, we identified several licorice constituents, viz., liquiritigenin, isoliquiritigenin, together with seven isoprenylated flavonoids and arylcoumarins, which could be key components responsible for the herb–drug interaction between cytochrome P450 and licorice. In addition, hydrophilic flavonoid glycosides and saponins may be converted into these P450 inhibitors in vivo. These studies represent a comprehensive examination of the potential effects of licorice components on the metabolic activities of P450 enzymes.

Biotransformation of 2α,5α,10β,14β-tetra-acetoxy-4(20), 11-taxadiene by Ginkgo cell suspension cultures

Abstract Ginkgo biloba cell suspension cultures were used to biotransform 2α,5α,10β,14β-tetra-acetoxy-4(20),11-taxadiene. Two novel compounds were obtained and their structures were identified as 9α-hydroxyl-2α,5α,10β,14β-tetra-acetoxy-4(20), 11-taxadiene 1 and 9α, 10β-dihydroxyl-2α,5α,14β-tri-acetoxy-4(20), 11-taxadiene 2 , respectively, on the basis of their physical and chemical data. Compound 1 was subsequently used as a substrate for the bioconversion by Ginkgo cell cultures, and the product obtained was confirmed to be the same as 2 , which suggested that 2 is biosynthesized from 1 . Investigation on properties of the related enzymes responsible for the biotransformation reaction through the experimental techniques of cell-free culture and substrate/product concentration analysis revealed that the enzymes were extracellular and constitutive.

Antcamphins A–L, Ergostanoids from Antrodia camphorata

Twelve ergostanoids, named antcamphins A-L (1-12), together with 20 known triterpenoids, were isolated from fruiting bodies of the medicinal fungus Antrodia camphorata. Compounds 1 and 2 represent the first examples of norergostanes isolated from A. camphorata, and compounds 3 and 4 are the first pair of cis-trans isomers of ergostane-type triterpenoids containing an aldehyde group. Compounds 5-12 are four pairs of C-25 epimers. The structures of 1-12 were elucidated on the basis of extensive spectroscopic data analysis including NMR and HRESIMS. Particularly, the absolute configurations at C-25 for 5-12 were determined by the modified Moshers method. These triterpenoids exhibited weak cytotoxic activities against MDA-MB-231 breast cancer cells and A549 lung cancer cells, but did not inhibit the growth of normal cells in the sulforhodamine B assay.

Biotransformation of 20(R)-panaxadiol by the fungus Rhizopus chinensis

Microbial transformation of 20(R)-panaxadiol by the fungus Rhizopus chinensis CICC 3043 yielded seven metabolites. Their structures were elucidated on the basis of extensive spectroscopic analyses. R. chinensis could catalyze hydroxylation and further dehydrogenation at C-24 of 20(R)-panaxadiol, as well as hydroxylation at C-7, C-15, C-16, and C-29. Three of these compounds at 10μM could moderately inhibit growth of HepG2 human hepatocellular carcinoma cells with an inhibition rate of about 40%. Three compounds (also at 10μM) showed approximately 30% inhibition on NF-κB transcriptional activity in SW480 human colon carcinoma cells stably transfected with NF-κB luciferase reporter and induced by LPS.

A Triterpenod Saponin from Albizia Julibrissin

A triterpenoid saponin (1) was obtained from the stem barks of Albizia julibrissin Durazz. Its structure was elucidated as 3-O-[beta-D-xylopyranosyl-(1 --> 2)-alpha-L-arabinopyranosyl-(1 --> 6)-beta-D-glucopyranosyl]-21-O-[(6S)-2-trans-2-hydroxymethyl-6-methyl-6-O-beta-D-quinovopyranosyl-2, 7-octadienoyl]-16-deoxy-acacic acid 28-O-beta-D-glucopyranosyl-(1 --> 3)-[alpha-L-arabinofuranosyl-(1 --> 4)]-alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl ester (1), named as Julibroside J26, based on the chemical and spectral methods.

Biotransformation of Podophyllotoxin to Picropodophyllin by Microbes

Biotransformation of podophyllotoxin (PT) by several microbial species has been investigated. Among the fungi tested, it was found that Penicillium strains can isomerize PT to picropodophyllin (PPT) in 8% yield and other strains also transform the substrate into the same product but with lower yield.