Boerechalasins A-G, cytochalasans from the fungus Boeremia exigua with anti-inflammatory and cytotoxic activities

Abstract

Seven previously undescribed cytochalasans, namely, boerechalasins A-G, together with one analogue, were characterized from the solid culture of the fungus Boeremia exigua. Their structures and absolute configurations were elucidated on the basis of extensive spectroscopic analysis as well as electronic circular dichroism calculations. Remarkably, boerechalasin F possessed an unusual sulfoxide moiety that might be derived from methionine, while boerechalasin G had an unusual 5-methylcyclohexane-1,2,3-triol substituent at N-2 position. Boerechalasins A and E exhibited inhibitory activities against nitric oxide production in LPS-induced RAW264.7 macrophages with IC₅₀ values of 21.9 and 5.7 μM, respectively. Boerechalasin F displayed cytotoxicity against human MCF‒7 cells with an IC₅₀ value of 22.8 μM.

Keywords: Boeremia exigua; Cytochalasans; Cytotoxicity; Didymellaceae; NO production inhibition.