Artemisinin (1) was transformed by Mucor polymorphosporus and Aspergillus niger. Five products were identified as 9β-hydroxyartemisinin (2), 3β-hydroxyartemisinin (3), deoxyartemisinin (4), 3β-hydroxydeoxyartemisinin (5), and 1α-hydroxydeoxyartemisinin (6). Products 2, 3, and 6 are new compounds.

Catharanthus roseus cell suspension cultures were used to bioconvert both triptolide (1) and triptonide (2). The same reaction path was followed in both biotransformations. Two biotransformed products were obtained and their structures identified as triptriolide (3) and 12β, 13α-dihydroxytriptonide (4), respectively, from 1 and 2. Product 4 is a new compound.

Ginkgo biloba cell suspension cultures were used to bioconvert sinenxan A, 2α, 5α, 10β, 14β-tetra-acetoxy-4 (20), 11-taxadiene, a taxoid isolated from callus tissue cultures of Taxus spp. Besides two major products, 9α-hydroxy-2α, 5α, 10β, 14β-tetra-acetoxy-4 (20), 11-taxadiene 1 and 9α, 10β-dihydroxy-2α, 5α, 14β-triacetoxy-4 (20), 11-taxadiene 2, additional six minor products were obtained and five of them identified as new compounds. On the basis of chemical and spectral data, their structures were identified as 9α,14β-dihydroxy2α, 5α, 10β-triacetoxy-4 (20), 11-taxadiene 3, 6α, 10β-dihydroxy-2α, 5α, 14β-triacetoxy-4 (20), 11-taxadiene 4, 6α, 9α, 10β-trihydroxy2α, 5α, 14β-triacetoxy-4 (20), 11-taxadiene 5, 9α, 10β-O-(propane-2, 2-diy1)-2α, 5α, 14β-triacetoxy-4 (20), 11-taxadiene 6, 9α-hydroxy2α, 5α, 10β, 14β-tetra-acetoxy-4 (20), 11-taxadiene formate 7, 10β-hydroxy-2α, 5α, 9α, 14β-tetra-acetoxy-4 (20), 11-taxadiene formate 8, respectively. Investigation of the properties of the enzymes responsible for the biocatalysis process of sinenxan A to 1 and 2 revealed that the enzymes were extracellular and constitutive. Using sinenxan A and the two major products (1 and 2) as indicators, the stage and concentration of sinenxan A added and the kinetics of the biotransformation reaction were investigated. The results showed that: (1) the optimal stage for sinenxan A addition was the logarithmic phase of the cell growth period, in which sinenxan A was almost completely bioconverted, and the biotransformation rates were up to 60 and 20% for 1 and 2, respectively; (2) the optimal concentration of sinenxan A added was 60mg/L; (3) the substrate was mainly converted into 1 and 2 in the first 48h after addition and then into the minor products.

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.

The diterpenoid triepoxides are the major active constituents of Tripterygium wilfordii with potent antitumor and immune activities. But the strong toxicity of these compounds has restricted their application to a great extent. In order to find more effective compounds with less toxicity, structural modifications of triptonide (1) by Aspergillus niger (AS 3.739) were investigated and four biotransformed products were obtained. Based on their chemical and spectral data, their structures were elucidated as 5αhydroxytriptonide (2), triptolide (3), 17-hydroxytriptonide (4), and 16-hydroxytriptonide (5), among which 2, 4 and 5 are new compounds. All the three new transformed products showed cytotoxic activities against the majority of the human tumor cell lines tested, however, they are found to possess less cytotoxic activity when compared with 1. Both compounds 4 and 5 showed similar cytotoxic activity and their IC50 values were 5-15 fold less than 1, while 2 is about 100 times less active than 1.