Tetrahydroisoquinoline-monoterpene and iridoid glycosides from Alangium lamarckii

From the water soluble fraction of the dried fruits of Alangium lamarckii, four tetrahydroisoquinoline-monoterpene glycosides, 6-O-methyl-N-deacetylis oipecosidic acid, 7-O-methyl-N-deacetylisoipecosidic acid, 6,7-di-O-methyl- N-deacetylisoipecosidic acid and 6"-O-alpha -D-glucopyranosyl-6-O-methyl-N- deacetylisoipecosidic acid, and an iridoid glycoside, 6'-O-alpha -D-glucopy ranosylloganic acid, were isolated, together with six known compounds. The structures of the previously unknown compounds were determined by spectrosc opic and chemical means. The significance of these glucosides in the biogen esis of Alangium alkaloids is discussed; 6-O- methyl-N-deacetylisoipecosidi c acid was also chemically converted into 10-O-demethylprotoemetine and dih ydroisoalangine. (C) 2001 Elsevier Science Ltd. All rights reserved.