ABSTRACT
A method has been developed for determining the major constituents of the plant commonly known in Thailand as “fah-talai-joan”, Andrographis paniculata (Burm.f) Wall. Ex Nees by high-performance liquid chromatography (HPLC); its constituents are andrographolide, neoandrographolide and 14-deoxy-11, 12-didehydroandro-grapholide. The reverse phase HPLC system consisted of a Lichrosorb R8 column, and acetonotrile/H2O/ethanol (21/56/20, v/v) as the mobile phase. The column effluent was monitored by a UV-detector at the 205 nm wave-length. The correlation of calibration curve of the lactones was r=0.9998, whereas the reproducibility study gave the percent C.V. of about 5 percent. With this analytical method, pharmacokinetics study of fah-talai-joan in both in situ and in vivo models was undertaken. It was found that 14-deoxy-11, 12-didehydroandro-grapholide was rapidly absorbed and neoandropholide was the poorest absorption compound. Andrographolide was administered orally to rats, the drug plasma concentration showed absorption with a rate constant of 0.0078 min.-1 Maxinum drug plasma level of 1.76 g/ml was observed at 2.04 hours after oral administration. The elimination half-life in rate was 1.34 hours. The developed analytical procedure as well as the pharmacokinetic parameters obtained from this investigation provide valuable information of future clinical efficacy studied of fah-talai-joan.