[Enzymatic glycosylation of 4'-demethylepipodophyllotoxin].

The glycosides of 4'-demethylepipodophyllotoxin (DMEP) possess various pharmacological activities; however, the chemical synthesis of these glycosides faces challenges in regioselectivity, stereoselectivity, and the protection and de-protection of functional groups. In this work, a novel glycosyltransferase (GT) gene AbGT5 from Aloe barbadensis was successfully cloned, heterogeneously expressed and purified. Recombinant AbGT5 was able to catalyze the glycosylation of DMEP and the glycosylated product, which was separated from the preparative scale reaction, was characterized as DMEP 4'-O-ß-D-glucoside via MS, 1H-NMR, 13C-NMR, HSQC and HMBC. According to the investigations of enzyme properties, AbGT5 show the highest activity around 20 ℃ in the buffer of pH 9.0, and it was independent of divalent metal ions. Under the optimum conditions, the conversion rate of DMEP can reach 80%. Above all, in this work the enzymatic glycosylation of DMEP was achieved with high efficiency by the novel GT AbGT5.

[Flavonoid glycosides from callus cultures of Dysosma versipellis].

Various chromatographic techniques, including silica gel column chromatography, Sephadex LH-20, preparative thin-layer chromatography, and preparative HPLC, were employed to isolate the chemical constituents from callus cultures of Dysosma versipellis. Structures of the compounds were elucidated based on UV, IR, MS and NMR spectroscopic data analysis. Totally, seven flavonoid glycosides were isolated from the 95% ethanol extract of the callus cultures and identified as kaempferol-3-O-[6″-(3″'-methoxy)-malonyl]-ß-D-glucopyranoside(1), kaempferol-3-O-(6″-O-acetyl)-ß-D-glucopyranoside(2), kaempferide-3-O-ß-D-glucopyranoside(3), kaempferol-3-O-ß-D-glucopyranoside(4), isoquercitrin(5), quercetin-4'-O-ß-D-glucopyranoside(6) and kaempferol-3-(6″-malonyl)-ß-D-glucopyranoside(7), respectively.All these compounds were isolated from callus cultures of D. versipellis for the first time.Compounds 1, 2, 3, 6 and 7 were firstly obtained from plant materials of D. versipellis, and compound 1 was a new compound.

[Cloning,expression and functional identification of secoisolariciresinol dehydrogenase gene from Dysosma versipellis callus].

Secoisolariciresinol dehydrogenase (SDH) is a key enzyme involved in the biosynthetic pathway of podophyllotoxin.In this study, two SDH candidate genes,SO282 and SO1223, were cloned from callus of Dysosma versipellis by homology-based PCR and rapid amplification of cDNA end (RACE).The SDH candidate genes were expressed in Escherichia coli and the subsequent enzyme assay in vitro showed that recombinant SO282 had the SDH activity. These results pave the way to the follow-up investigation of the biosynthetic of podophyllotoxin.

[A new lactone derivative from plant endophytic fungus Periconia sp. F-31].

To investigate the secondary metabolites of endophytic fungi Pericinia sp. F-31. Column chromatography on silica gel, Sephadex LH-20 and semi-preparative HPLC were used to separate and purify the compounds. Two compounds were isolated from the fermentation broth of Periconia sp. Their structures were identified as 5-(1-hydroxyhexyl) -6-methyl-2H-pyran-2-one (1) and 2-(3-hydroxy-4-methylphenyl) -propanoic acid (2). Compound 1 was a new lactone compound, compound 2 was new natural product, and the NMR data of compound 2 was reported for the first time.

[Sulfation of naringenin by Mucor sp].

Naringenin (1) was transformed to three metabolites (2-4) by Mucor sp. Based on LCMS(n)-IT-TOF and NMR spectroscopic data, 2-4 were identified as naringenin-7-O-sulphate, naringenin-4'-O-sulphate, and naringenin-5-O-sulphate, respectively. These results might provide hints to the mammalian/human metabolism of naringenin.

[Regulation of syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid biosynthesis in cell suspension cultures of Saussurea involucrata].

Syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid are three main bioactive ingredients in herbs of Saussurea involucrata with various pharmacological properties, while their contents are very low. In this study, the biosynthesis of syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid in the cell suspension cultures of S. involucrata were regulated by feeding carbon sources and precursors, which resulted in a great increase of the contents and yields of the above three bioactive ingredients. After 16 days of fermentation, the yields of syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid reached 339.0, 225.3, 512.7 mg x L(-1), respectively. Meanwhile, their contents increased up to 67.9, 1.9, 10.6 times of wild medicinal material, respectively. The results provided a solid basis for further studies on application of cell suspension cultures of S. involucrata for large-scale production of bioactive compounds syringin, chlorogenic acid and 1,5-dicaffeoylquinic acid.

[Diversity and in vitro antitumnor activity of endophytic fungi from mangrove plants Xylocarpus].

A total of 24 biologically pure entophytic fungal strains were isolated from stems, leaves, and seed coats of Xylocarpus plants by repeated purification, and identified with Internal Transcribed Spacer (ITS) rDNA molecular method, which belonging to 14 genera, 11 families, 9 orders and 3 classes. There were differences in genus and species levels among three plant materials from different habitats and species, and it was found that the strains of Phomopsis and Colletotrichum existed in all three plant materials. In vitro assay of antitumor activity by MTT method revealed that the EtOAc extracts of 15 strains exhibited potent antitumor activity. These results suggest that it is of value for further investigation on the above fungal strains.

[Chemical constituents from cell suspension cultures of Cudrania tricuspidata].

Ten compounds were isolated and purified from cell suspension cultures of Cudrania tricuspidata with silica-gel column chromatography, semi-preparative HPLC and Sephadex LH-20. On the base of their physicochemical properties and spectral data, their structures were identified as 1, 3, 5-trihydroxy4-(3, 3-dimethylallyl) xanthone (1), wighteone (2), 6-prenylapigenin (3), licoflavone C(4), cudraflavanone C(5), erythrivarone A (6), derrone (7), carthamidin (8), genistein (9) and aromadendrin (10). Among them, compounds 2-10 were flavonoids, and compound 1 was a xanthone which was isolated from the plant for the first time.

[Chemical constituents from cell cultures of Morus alba].

The column chromatography on silica gel, Sephadex LH-20 and semi-preparative HPLC were used to separate and purify the compounds from the EtOAc extract of medium and MeOH extract of cell cultures of Morus alba. Eight compounds were isolated. Based on physico-chemical properties and spectroscopic data, their structures were identified as isobavachalcone (1), genistein (2), norartocarpetin (3), albanin A (4), guangsangon E (5), mulberrofuran F (6), chalcomoracin (7), kuwanon J (8). Compounds 3-6 were isolated from the cell cultures of M. alba for the first time.

[Isolation and analysis of syringin in cell suspension cultures of Saussurea involucrata].

Syringin is one of the main bioactive ingredients in Saussurea involucrata. In this study, various chromatographic techniques were employed to isolate and purify syringin in the polar extraction of cell suspension cultures of S. involucrata. The structure of syringin was characterized by the analysis of spectroscopic data. A quantitative analytical method for the content of syringin in cultures of S. involucrata was established with RP-HPLC. The method is convenient, accurate and reliable. All this results provided a basis for further studies on application of cell suspension cultures of S. involucrata for large-scale production of bioactive compound syringin.