A new cytochalasan alkaloid, westalsan (1), along with two known cytochalasan compounds, phomacin B (2) and 19-hydroxy-19,20-dihydrophomacin C (3), were isolated from the solid rice culture of Westerdykella nigra, a marine-derived endophytic fungus, isolated from the roots of mangrove Avicennia marina (Forssk.) Vierh. The structures of compounds 1-3 were established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with HR-ESI-MS. The ability of the isolated compounds to inhibit acetylcholine esterase activity was evaluated. Compound 3 showed the highest acetylcholine esterase inhibitory activity (IC50 0.056±0.003 μM), followed by compound 1 (IC50 0.088±0.005 μM) and compound 2 (IC50 0.140±0.007 μM) compared to donepezil (IC50 0.035±0.002 μM). This was further confirmed by molecular docking experiment.
Keywords: Westerdykella nigra; acetylcholine esterase; cytochalasan; molecular docking.
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