A new natural quaternary indole alkaloid isolated from Tabernaemontana laeta Mart. (Apocynaceae)

A new natural quaternary alkaloid, N-b-methylvoachalotine (1), was obtained from the root bark of Tabernaemontana laeta together with three dimeric in dole alkaloids, conodurine (2), voacamine (3) and tabernamine (4), and the monomeric indole alkaloids 19S-heyneanine (5), coronaridine (6) and voacang ine (7). The known triterpenes alpha -amyrin acetate, beta -amyrin acetate, lupeol acetate and taraxasterol acetate and the phytosterol beta -sitoster ol and its 3-O-beta -D-glucoside were also identified. The structures of th e compounds were elucidated based on spectroscopic studies.