ISOLATION OF A MULTIDRUG-RESISTANCE INHIBITOR FROM ACONITUM PSEUDO-LAEVE VAR. ERECTUM

hTo overcome multidrug resistance (MDR) in cancer chemotherapy, we pre pared various plant Extracts and searched for a component which is eff ective for inhibition of MDR. MDR inhibition activity was determined b y measuring cytotoxicity to MDR cells using multidrug resistant human fibrocarcinoma KB V20C, which is resistant to 20 nM vincristine and ex presses high level of mdr1 gene. Of various plant extracts, the MeOH e xtract of the root of Aconitum pseudo-laeve var. erectum was found to have potent inhibitory activity on MDR. The bioassay-guided fractionat ion of the MeOH extract of the plant led to the isolation of an alkalo id, lycaconitine, as an active principle. And the IC50 of lycaconitne for KB V20C cells was 74 mu g/ml.