Isolation of a new isomer of (+)-leucofisetinidin from Cassia marginata leaves

Abstract

Cassia marginata Roxb. (family: Leguminosae) is a small deciduous tree growing in the forests from South Arcot to Travancore (India) and often planted for 0rnament. The bark of the tree is a good tanning material and has been found to be a substitute for wattle and avaram. The present communication describes the isolation and identification of (+)-catechin, butein 4'-glucoside (coreopsin), and a new dextrorotatory isomer of leucofisetinidin from the Cassia marginata leaves. (+)-Catechin and butein 4'-glucoside were separated by cellulose column chromatography; the former was identified by comparison of its infrared spectrum, analytical values, and R, values with those of the authentic sample and also by mixed melting points of the compound and its derivatives with authentic samples. Butein 4'-glucoside (coreopsin) was identified by thoroughly comparing it with an authentJic sample. The presence of butein 4'-glucoside (coreopsin) was earlier noticed in several plants. Though the compound seems to occur widely in nature, its presence in a Leguminosae plant is noted for the first time. The (+)-leucofisetinidin was found to be a new dextrorotatory isomer of 7,3',4'-trihydroxyflavan-3,4-diol, since the melting points and rotation of this compound and its derivatives (see Experimental) were quite different from those of the corresponding isomers of (+)-7,3',4'-trihydroxyflavan-3,4-diol.