Secondary metabolites from the roots of Engelhardia roxburghiana and their antitubercular activities

Engelharquinone (1), engelharquinone epoxide (2), engelharolide (3), and engelhardic acid (4), were isolated as naturally occurring products from a plant source, Engelhardia roxburghiana together with 20 previously known compounds, four of which were hitherto not known as plant constituents. Their structures were identified by means of spectroscopic analysis. A biological evaluation showed that three of the previously isolated antitubercular constituents [(-)-4-hydroxy-1-tetralone, 3-methoxyjuglone and engelhardione] and engelharquinone (1) exhibited moderate antitubercular activity against Mycobacterium tuberculosis 90-221387.