NEW ISOQUINOLINE ALKALOIDS ISOLATED FROM ANIBACANNELILLA H-B-K (LAURACEAE) IN BOLIVIA

Eleven benzyltetrahydroisoquinoline alkaloids, with an original substi tution pattern, were isolated from the stem bark of Aniba canelilla H. B.K. (Lauraceae). Structural studies of these compounds including H-1, C-13, nOe difference, COSY H-H and C-H, and COLOC nuclear magnetic re sonance spectroscopy led to the identification of four benzylisoquinol ines, monosubstituted on ring C with an hydroxyl at C-11, (-)-norcanel illine 2, (+)-canelilline 3, anicanine 4, and canelillinoxine 5; two t etrahydroprotoberberines monosubstituted on ring D at C-9, (-)-anibaca nine 6 and (+)-manibacanine 8: two tetrahydroprotoberberines monosubst ituted on ring D at C-11, (-)-pseudoanibacanine 7 and (+)-pseudomaniba canine 9; and three protoberberines with the same substitution pattern on rings A and D with a methyl substituent at the 8alpha or 8beta pos ition, (-)-alpha-8-methylpseudoanibacanine 10, (-)-beta-8-methylpseudo anibacanine 11, and (-)-alpha-8-methylanibacanine 12. An examination o f all isolated alkaloids suggests the existence of two enzymatic syste ms in A; canelilla. In the first enzymatic system, reticuline- and coc laurine-type alkaloids are involved in the bioconversion of classical proaporphine and aporphine alkaloids. In the second system, canelillin e-type alkaloids are intermediate in biosynthesis of anibacanine and p seudoanibacanine protoberberine alkaloids.