THE METABOLISM OF AVERMECTIN-B1A, AVERMECTIN-H2B1A, AVERMECTIN-H2B1B BY LIVER-MICROSOMES

  • 1 January 1982
    • journal article
    • research article
    • Vol. 10  (3) , 268-274
Abstract
The avermectins are a new class of structurally related antiparasitic agents isolated from Streptomyces avermitilis. The major polar metabolites isolated from in vitro incubations of [3H]avermectins B1a, H2B1a and H2B1b with rat or steer liver microsomes were isolated and identified as the C24-methyl alcohols of the parent compounds. A smaller quantity of a more polar metabolite was also identified as the monosaccharide of the C24-methyl alcohols of avermectin H2H1b from rat liver microsomal incubation and avermectin H2B1a from steer liver microsomal incubation. The mass spectra and 300-MHz 1H-NMR spectra permitted assignment of structures to these metabolites. Together these 2 metabolites represent 50-80% of the total radioactivity more polar than the parent compounds. The metabolite profiles on reverse-phase HPLC [high pressure liquid chromatography] demonstrate that the rat and steer are qualitatively similar in the production of these 2 polar metabolites.