Studies on the Alkaloids of Menispermaceous Plants. CCXXXI. : Alkaloids of Limacia cuspidata (MIERS) HOOK. f. et THOM. (1) The Structure of Limacine, Limacusine and Cuspidaline, New Phenolic Bisbenzylisoquinoline Bases

Abstract

Basic components of Bornean Limacia cuspidata (MIERS) HOOK et THOM. (Menispermaceae) were examined and three new phenolic, bisbenzylisoquinoline-type alkaloids, limacine, limacusine, and cuspidaline, were isolated and their structure identified. Limacine (I), m.p. 154∼156°, [α]_D -212° (CHCl₃). The various properties of this alkaloid agreed with those of fangchinoline except for the direction of its rotation. Limacusine (III), m.p. 235∼237°, [α]_D +110°. Its O-methyl compound was identified with N-methyldihydroepistephanine-B (II). From its NMR and MS, limacusine was assumed to be represented by the formula III. Cuspidaline (IV), oil. [α]_D -48° (CHCl₃). Its O-methyl compound was identified with O-methyldauricine (V). Its structure was presumed from the result of cleavage reaction of its O-ethyl compound with sodium in liquid ammonia. Biogenetical relationship among these three kinds of bases was considered and it was assumed that limacine (I) and limacusine (III) were formed by the intramolecular dehydrogenative condensation of cuspidaline (IV).