Absolute configurations and anti-bacterial activity of two century-old maleidrides

Two century-old maleidrides 1 and 2 were found in the marine-derived fungus Talaromyces trachyspermus. Their structures were established by the analysis of spectroscopic data. Notably, their absolute configurations were unambiguously assigned by X-ray diffraction analysis. Interestingly, compound 1 showed antibacterial activity against Escherichia coli (IC50 = 103.6 mg/mL). This was the first report on the absolute configuration of compound 2, which has not been determined for near a century.