Junhua Zheng

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.

New apiose-containing triterpenoid saponins from Conyza blinii

Abstract Four new apiose-containing triterpenoid saponins, conyzasaponins D, E, F, and H, were isolated from the aerial parts of Conyza blinii . They are the first examples of triterpenoid saponins containing one apiose unit whose C-2 is substituted by a galactose. Conyzasaponins D and F have two apiose units, a sugar that has been rarely observed in natural products research. Their structures were established on the basis of extensive NMR studies and chemical degradation. Conyzasaponins D and F exhibited moderate cytotoxicity against HL-60 cell lines.

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.