Bioactive proanthocyanidins from the root bark of Cassia abbreviata

Cassia abbreviata is an important medicinal plant used in the treatment of various infectious diseases. The ethnomedical efficacy of extracts of this plant species is attributed to its phytochemical constituents most of which are phenolics and anthraquinones. The aim of this study was to isolate and elucidate bioactive phenolic compounds from the root bark of this species. Consequently, two novel trimmeric proanthocyanidins; 3,7,4'-trihydroxyflavan-(4β→8)-3,5,7,4'-tetrahydroxyflavan-(3'→6)-3,5,7,2',4'- pentahydroxyflavan (cassinidin A) and 3,7,2',4'-tetrahydroxyflavan-(4α→8)-3,5,7,4'-tetrahydroxyflavan-(4α→6)-3,5,7,2',4'-pentahydroxyflavan (cassinidin B) were isolated from the root bark of Cassia abbreviata. The chemical structures were determined using NMR, MS and HRMS spectroscopic data. The cassinidin A and B showed higher to moderate antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Candida mycoderma.Keywords: Medicinal plant, Cassia abbreviata, Caesalpinioideae, root bark, Cassinidin A, Cassinidin B, antimicrobia