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.

Thirteen compounds were isolated from the anomalous fruits of Gleditsia sinensis on the basis of bioassay-guided fractionation. These saponins together with six analogues or related compounds were tested for their cytotoxicities against six tumor cell lines by the MTT method. The induction of apoptosis in HL60 cells by these compounds was determined through flow cytometric analysis. Some structure-activity relationships in cytotoxicity and induction of apoptosis were identified. The evaluation of the cytotoxicity and the ability to induce apoptosis revealed that some important structural features are required for activity. A valuable model which enables prediction of their activities was established and may be employed for the drug design of new Gleditsia saponin analogues.

Microbial transformations of artemisinin 1 by Cunninghamella echinulata (AS 3.3400) and Aspergillus niger (AS 3.795) were carried out. Two products, 10β-hydroxyartemisinin 2 and 3α-hydroxydeoxyartemisinin 3, were obtained. Their structures were identified on the basis of chemical and spectroscopic data. 10β-Hydroxyartemisinin is a new compound.