The plant Andrographis paniculata found throughout Southeast Asia contains Andrographolide 1, a diterpenoid lactone, which has antitumour activities against in vitro and in vivo breast cancer models. In the present study, we report on the synthesis of andrographolide derivatives, 3,19-isopropylideneandrographolide (2), 14-acetyl-3,19-isopropylideneandrographolide (3) and 14-acetylandrographolide (4), and their in vitro antitumour activities against a 2-cell line panel consisting of MCF-7 (breast cancer cell line) and HCT-116 (colon cancer cell line). Compounds 2 and 4 were also screened at the US National Cancer Institute (NCI) for their activities against a panel of 60 human cancer cell lines derived from nine cancer types. Compound 2 was found to be selective towards leukaemia and colon cancer cells, and compound 4 was selective towards leukaemia, ovarian and renal cancer cells at all the dose-response parameters. Compounds 2 and 4 showed non-specific phase of the cell cycle arrest in MCF-7 cells treated at different intervals with different concentrations. NCI's COMPARE and SOM mechanistic analyses indicated that the anticancer activities of these new class of compounds were not similar to that of standard anticancer agents, suggesting novel mechanism(s) of action.

The objectives of the present study were (i) to study the pharmacogenetics of UGT1A1*6, UGT1A1*28 and ABCG2 c.421C> > > >A in three distinct healthy Asian populations (Chinese, Malays and Indians), and (ii) to investigate the polygenic influence of these polymorphic variants in irinotecan-induced neutropenia in Asian cancer patients. Pharmacokinetic and pharmacogenetic analyses were done after administration of irinotecan as a 90-min intravenous infusion of 375 mg/m 2 once every 3 weeks (n = = = = 45). Genotypic-phenotypic correlates showed a non-significant influence of UGT1A1*28 and ABCG2 c.421C> > > >A polymorphisms on the pharmacokinetics of SN-38 (P > > > > 0.05), as well as severity of neutropenia (P > > > > 0.05). Significantly higher exposure levels to SN-38 (P = = = = 0.018), lower relative extent of glucuronidation (REG; P = = = = 0.006) and higher biliary index (BI; P = = = = 0.003) were found in cancer patients homozygous for the UGT1A1*6 allele compared with patients harboring the reference genotype. The mean absolute neutrophil count (ANC) was 85% lower and the prevalence of grade 4 neutropenia (ANC ≤ ≤ ≤ ≤ 500/µ µ µ µL) was 27% in patients homozygous for UGT1A1*6 compared with the reference group. Furthermore, the presence of the UGT1A1*6 allele was associated with an approximately 3-fold increased risk of developing severe grade 4 neutropenia compared with patients harboring the reference genotype. These exploratory findings suggest that homozygosity for UGT1A1*6 allele may be associated with altered SN-38 disposition and may increase the risk of severe neutropenia in Asian cancer patients, particularly in the Chinese cancer patients who comprised 80% (n = = = = 36) of the patient population in the present study. (Cancer Sci 2007; 98: 1461-1467)

Background and purpose: Andrographolide, the major phytoconstituent of Andrographis paniculata, was previously shown by us to have activity against breast cancer. This led to synthesis of new andrographolide analogues to find compounds with better activity than the parent compound. Selected benzylidene derivatives were investigated for their mechanisms of action by studying their effects on the cell cycle progression and cell death. Experimental approach: Microculture tetrazolium, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and sulphorhodamine B (SRB) assays were utilized in assessing the in vitro growth inhibition and cytotoxicity of compounds. Flow cytometry was used to analyse the cell cycle distribution of control and treated cells. CDK1 and CDK4 levels were determined by western blotting. Apoptotic cell death was assessed by fluorescence microscopy and flow cytometry. Key results: Compounds, in nanomolar to micromolar concentrations, exhibited growth inhibition and cytotoxicity in MCF-7 (breast) and HCT-116 (colon) cancer cells. In the NCI screen, 3,19-(2-bromobenzylidene) andrographolide (SRJ09) and 3,19-(3-chloro-4-fluorobenzylidene) andrographolide (SRJ23) showed greater cytotoxic potency and selectivity than andrographolide. SRJ09 and SRJ23 induced G 1 arrest and apoptosis in MCF-7 and HCT-116 cells, respectively. SRJ09 downregulated CDK4 but not CDK1 level in MCF-7 cells. Apoptosis induced by SRJ09 and SRJ23 in HCT-116 cells was confirmed by annexin V-FITC/PI flow cytometry analysis. Conclusion and implications:The new benzylidene derivatives of andrographolide are potential anticancer agents. SRJ09 emerged as the lead compound in this study, exhibiting anticancer activity by downregulating CDK4 to promote a G 1 phase cell cycle arrest, coupled with induction of apoptosis.

These findings suggest that (1) SLCO1B1 haplotypes may have a significant influence on the disposition of irinotecan and its metabolites in Asian cancer patients, and (2) patients with SLCO1B1*15 haplotype may be susceptible to increased sensitivity to irinotecan, which may manifest itself either by increased efficacy or toxicity or both owing to the increased exposure levels to 7-ethyl-10-hydroxycamptothecin.