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.

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.

Microbial transformation was used to prepare novel cytotoxic bufadienolides. Twelve products (3-14) were obtained from bufalin (1) by the fungus Mucor spinosus. Their structures were elucidated by high-resolution mass spectroscopy (HR-MS) and extensive NMR techniques, including 1H NMR, 13C NMR, DEPT, 1H-1H correlation spectroscopy (COSY), two dimensional nuclear Overhauser effect correlation spectroscopy (NOESY), heteronuclear multiple quantum coherence (HMQC), and heteronuclear multiple bond coherence (HMBC). Compounds 3, 4, 9 and 11-14 are new mono-or dihydroxylated derivatives of bufalin with novel oxyfunctionalities at C-1β, C-7β, C-11β, C-12β and C-16α positions. The in vitro cytotoxic activities against human cancer cell lines of 3-14, together with 16 biotransformed products derived from cinobufagin (15-30) were determined by the MTT method, and their structure-activity relationships (SAR) were discussed.

A sensitive and rapid high-performance liquid chromatography (HPLC) method with solid-phase extraction (SPE) to simultaneously determine albiflorin and paeoniflorin in rat serum was described. Serum samples were pretreated with solid-phase extraction using Extract-CleanTM cartridges, and the extracts were analyzed by HPLC on a reversed-phase C18 column and a mobile phase of acetonitrile-0.03% formic acid (17:83 (v/v)) with ultraviolet detection at 230nm. Pentoxifylline was used as the internal standard (IS). The linear ranges of the calibration curves were 29-1450ng/ml for albiflorin and 10-2000ng/ml for paeoniflorin. The intra-and inter-day precisions (R.S.D.) were≤10.49% for albiflorin and≤11.29% for paeoniflorin, respectively. Mean recovery was determined to be 89.75% for albiflorin and 85.82% for paeoniflorin. The limit of quantification was 29ng/ml for albiflorin and 10ng/ml for paeoniflorin, respectively. The validated method was applicable to pharmacokinetic studies of albiflorin and paeoniflorin from rat serum after oral administration of Si-Wu decoction. The pharmacokinetic study indicated that albiflorin and paeoniflorin had poor absorption and rapid elimination. This assay result was necessary for the pharmacokinetic evaluation of Si-Wu decoction.

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.

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.

Four major active saponins (ginsenosides Rg1, Rb1, Rd and notoginsenoside R1) in Panax notoginseng were determined in rat urine after oral and intravenous administration of total saponins of P. notoginseng (PNS), and the urine samples were treated with solid-phase extraction (SPE) prior to liquid chromatography. A reversed-phase liquid chromatography system with ultraviolet detection and a Zorbax SB-C18 column was used. The within-day and between-day assay coefficients of variation for the four saponins in urine were less than 7% and the recovery of this method was higher than 85%. Using this method, the excretion profile of the drug in rat urine after administration of PNS was revealed for the first time.

The biotransformation of cinobufagin by cell suspension cultures of Catharanthus roseus was investigated. After 6 days incubation, four new glucosylated derivatives, desacetylcinobufagin 16-O-β-D-glucoside, 3-epi-desacetylcinobufagin 16-O-β-D-glucoside, 3-oxo-desacetylcinobufagin 16-O-β-D-glucoside, and cinobufagin 3-O-β-D-glucoside, respectively, were isolated and identified on the basis of their physical and chemical data. This is the first report of bufadienolides with a glucosyl substituent at the C-16 position.

Nine new triterpenoid saponins, conyzasaponins I-Q (1-9), were isolated from the aerial parts of Conyza blinii. Their structures were established on the basis of extensive 1D and 2D NMR spectra as well as by chemical degradations. Among these compounds, conyzasaponins M-O (5-7) share a common pentasaccharide unit attached to C-28 of the aglycon, 28-O-β-D-apiofuranosyl-(1→3)-β-D-xylopyranosyl-(1→4)-[β-D-apiofuranosyl-(1→3)]-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester, which contains two apiofuranosyl residues. To the best of our knowledge, they are among the few examples of natural products possessing two apiofuranose units in a single sugar chain.

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.