Biosynthesis of Phenolic Tetrahydroisoquinoline Alkaloids of Peyote’

THOUGH in uivo investigations of the biosynthesis of mescaline in peyote (Lophophoru williamsii (Lem.) Coult.) are relatively complete,*-‘0 reports on the biosynthesis of the isoquinoline alkaloids are less so. Battersby et al. l1 have reported the incorporation of tyrosine into pellotine, lophophorine and anhalonidine. Further, they demonstrated that dopamine was incorporated into pellotine and that the methyl group of methionine served as a precursor of the O-methyl groups but not of the C-l and C-9 positions of this alkaloid. While 1-14C-labeled acetate was incorporated into pellotine, the activity was found to be evenly distributed between the C-l and C-9 positions suggesting that it is not incorporated directly. Subsequently, these authors have reported l2 that though 4-hydroxy-3-methoxyphenethylamine serves as a precursor of pellotine 5-hydroxy-3,4-dimethoxyphenethylamine does not. When r4C-labeled pellotine was introduced into plants, 4.9 per cent of the radioactivity was recovered as anhalonidine. However when 14C-labeled anhalonidine was introduced, only l-5 per cent of the radioactivity was recovered as pellotine. Leete* has also shown that tyrosine acts as a precursor of anhalonidine. In addition, _Leete and Braunstein” have reported that 3-14C-labeled pyruvate was incorporated into the C-l and C-9 unit of anhalonidine. The percentage of incorporation (0.06 per cent) and the distribution of activity (28 per cent in C-l ; 72 per cent in C-9) suggests that pyruvate is not incorporated directly. Lundstrom and Agurellg have reported that the methyl group of