Antibacterial activity of naphthoquinones and triterpenoids from Euclea natalensis root bark.

Phytochemical studies of an ethanolic extract of Euclea natalensis root bark afforded two new compounds, octahydroeuclein (1) and 20(29)-lupene-3 beta-isoferulate (2), in addition to three known compounds, shinanolone (3), lupeol, and betulin. The chemical structures of 1 and 2 were determined by spectroscopic means. Shinanolone (3) showed inhibitory activity against Gram-positive bacterial strains and a drug-sensitive strain of Mycobacterium tuberculosis at a concentration of 0.1 mg/mL.