Microsomal activation of constituents of white snakeroot (Eupatorium rugosum Houtt) to form toxic products.

Components of white snakeroot, a plant toxic to livestock and human beings, were activated by Aroclor 1254-induced rat liver microsomes. The toxic products of microsomal activation were evaluated in murine melanoma (B16F1) cell cultures. Toxic products in white snakeroot were inactive in cell culture systems without microsomal activation. This activation system revealed that at least 2 fractions of white snakeroot were metabolically activated to cytotoxic agents. The autocatalytic inactivator of cytochrome P-450, 1-aminobenzotriazole, inhibited activation of white snakeroot constituents by rat liver microsomes.