Xylatolides A and B, new 10-membered macrolides from the endophytic fungus Xylaria sp.

Abstract Chemical investigation of the fungal endophyte Xylaria sp. isolated from leaves of Moringa oleifera , collected in Cameroon, resulted in the previously undescribed 10-membered macrolide, and two known natural products. The structures of the xylatolides A and B were unambiguously identified by their mass spectra and by extensive 1D and 2D NMR spectroscopic analysis, featuring a 10-membered lactone core structure with oxygenated substituents and an unsubstituted 10-alkyl chain presenting seven carbon atoms. Compounds were screened for their cytotoxic potential against the human HepG2 hepatocellular carcinoma cells and HCT-116 cells (human colon carcinoma cell line). Moreover, the isolated compounds were also assayed against a small panel of sensitive strains including the bacterial species Escherichia coli , Staphylococcus aureus , and Mycobacterium tuberculosis as well as against the fungal species Candida albicans . However, no significant activities were found.