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.

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.

A new HPLC method for the determination of paeoniflorin in rat serum with solid-phase extraction (SPE) for preconcentration is introduced. Paeoniflorin and an internal standard (pentoxifylline) were extracted from serum by means of SPE using cartridges with octadecyl chemically bound phase. The HPLC separation was then performed on a reversed-phase C18 column using acetonitrile-water (18:82, v/v) as eluting solvent system, and UV detection at 230nm to measure the analyte with a limit of quantitation about 10ngml-1. The calibration curve for paeoniflorin was linear (r=0.9938) in the concentration range of 10-1200ngml-1, both intra-and inter-day precision of the paeoniflorin were determined and their coefficience of variation did not exceed 10%. The validated method has been successfully applied for pharmacokinetic studies of paeoniflorin from rat serum after oral administration of Guan-Xin-Er-Hao decoction.

Biotransformation of triptolide 1 by Cunninghamella blakesleana (AS 3.970) was carried out. Seven biotransformation products were obtained and four of them were characterized as new compounds. On the basis of their NMR and mass spectral data, their structures were characterized as 5α-hydroxytriptolide 2, 1β-hydroxytriptolide 3, triptodiolide 4, 16-hydroxytriptolide 5, triptolidenol 6, 19α-hydroxytriptolide 7 and 19β-hydroxytriptolide 8 All the new transformed products (2, 3, 7 and 8) were found to exhibit potent in vitro cytotoxicity against some human tumor cell lines.

The biotransformations of cinobufagin (1), an animal-originated bufadienolide, by cell suspension cultures of Catharanthus roseus and Platycodon grandiflorum were investigated. Incubation for 6 days of 1 with C. roseus yielded four products, desacetylcinobufotalin (2), 3-epi-desacetylcinobufagin (3), 1β-hydroxyl desacetylcinobufagin (4) and 3-epi-desacetylcinobufotalin (5), among which 4 is a new compound. Time course investigation revealed that the biotransformation rates of two major products, 2 and 3, reached their highest levels of 44.7 and 16.5%, respectively, on the third day after substrate administration. Compounds 2-5 showed more potent cytotoxic activities against HL-60 cell lines than the parent compound 1. A plausible biotransformation pathway is proposed to account for the formation of the observed products. From the culture supernatant of P. grandiflorum, 2 was isolated in 37.8% yield after 8 days of incubation with 1. Cinobufotalin (6) and desacetylcinobufagin (7) were also obtained as minor products. The two plant suspension cultures exhibited similar transformation patterns on compound 1.