Palmaenones A and B, two new antimicrobial chlorinated cyclopentenones from discomycete Lachnum palmae.

Two new antimicrobial chlorinated cyclopentenones, palmaenones A (1) and B (2) were isolated from the culture broth of discomycete Lachnum palmae (NBRC-106495), and the structures of 1 and 2 were elucidated by spectroscopic data and the stereochemistry of 1 was directly determined by a single-crystal X-ray diffraction analysis. Palmaenones A (1) and B (2) are cyclopentenones containing three chlorines. Compound 1 exhibited potent antimicrobial activity against Micrococcus luteus, Mycobacterium smegmatis, Escherichia coli, Xanthomonas campestris, and Mucor racemosus, while the activities of compound 2 were weaker than 1.