EFFECTS OF FEEDING ARTEMISIA-FILIFOLIA AND HELENIUM-FLEXUOSUM ON RABBIT CYTOCHROME-P450 ISOZYMES

Six groups of 4 rabbits each were treated as follows: Control; phenoba rbital (PB); 3-methylcholanthrene (3MC); proadifen hydrochloride (SKF- 525A); Artemisia filifolia and Helenium flexuosum. Prototype P450 indu cers (PB and 3MC) increased basal hepatic cytochrome P450 content by 2 -3 fold whereas the P450 inhibitor (SKF-525A) had no effect on basal c ytochrome P450 content. PB-induction of hepatic microsomes significant ly increased the rate of dealkylation of long alkyl chain alkoxyresoru fin ethers, benzyloxyresorufin and pentoxyresorufin 47-fold and 17-fol d, respectively, but had little or no effect on short alkyl chains. 3M C-induction of microsomes increased dealkylation of all alkoxyresorufi n ethers tested, preferentially dealkylating ethers with short alkyl c hain in the order: methoxy>ethoxy>propoxy. Artemisia filifolia or Hele nium flexuosum had no effect on basal hepatic cytochrome P450 content. However, microsomal dealkylation activity of short alkyl chain alkoxy resorufin ethers (methoxy, ethoxy and propoxy) was inhibited approxima tely 50%. When these plants are eaten for several days, they may inhib it biotransformation processes in herbivores through the same isoenzym es induced by 3MC.