Fusarithioamide A, a new antimicrobial and cytotoxic benzamide derivative from the endophytic fungus Fusarium chlamydosporium.

Four secondary metabolites (1-4), including a new benzamide derivative, namely fusarithioamide A (2-(2-aminopropanamido)-N-(1-hydroxy-3-mercaptopropyl) benzamide, 4) and three known compounds; 1-O-acetylglycerol (1), 8-acetylneosolaniol (2), and ergosta-7,22-diene-3β,5α,6β-triol (3) were characterized from the EtOAc extract of Fusarium chlamydosporium isolated from the leaves of Anvillea garcinii (Burm.f.) DC. (Asteraceae). The structures of the isolated metabolites were verified by using 1D and 2D NMR experiments as well as HRESIMS spectral data. Compounds 1-3 were firstly separated from this fungus. Compound 4 has been tested for their antibacterial and antifungal activity against different microorganisms using disc diffusion assay. It showed antibacterial potential towards B. cereus, S. aureus, and E. coli with inhibition zone diameters (IZDs) of 19.0, 14.1, and 22.7 mm, respectively and MICs values of 3.1, 4.4, and 6.9 μg ml-1, respectively. Also, it exhibited the most potent antifungal activity towards C. albicans (IZD 16.2 mm) comparable to clotrimazole (IZD 18.5 mm, positive control). Furthermore, compounds 1-4 were evaluated for their in vitro cytotoxic effect against KB, BT-549, SK-MEL, and SKOV-3 cell lines. Compounds 4 possessed potent and selective activity towards BT-549 and SKOV-3 cell lines with IC50 values of 0.4 and 0.8 μM, respectively compared to doxorubicin (IC50 0.046 and 0.313 μM, respectively). Moreover, 3 exhibited significant activity towards all tested cell lines. Fusarithioamide A may provide new promising candidates for potential antimicrobial and cytotoxic agent.