Chemical constituents of Securidaca longipedunculata root bark and evaluation of their antibacterial activities

Abstract

The Bioassay-guided sequential extraction and column chromatographic separation of theroot bark of Securidaca longipedunculata led to the isolation of three phenolic compounds; two benzoic acid derivatives (1 and 2) and a xanthone (3). The structures ofthese compounds were established based on the spectroscopic analyses including NMR( 1 H and 13 C NMR, 1 H- 1 H COSY, HMQC, and HMBC), MS, IR, UV-Vis and comparison with reported literature. In an in vitro antibacterial assay of the crude extracts and the pure compounds against four bacterial strains (S. aureus ATCC 25923, B. subtilis ATCC 6633,E. coli ATCC 35218, P. aeruginosa ATCC 27853), almost all crude extracts showed significant anti bacterial activity with acetone extract exhibited highest activity against B.subtilis and P. aeruginosa. Whereas, only compound 3 showed activity against the tested bacterial strains with the highest activity observed against B. subtilis with inhibition zone diameter 15 mm, which is comparable to that of the reference drug (gentamycin).