A novel hemiacetal from the marine-derived fungus Penicillium citrinum

A novel hemiacetal, citrinacetal (1) was isolated from a marine-derived fungus Penicillium citrinum by column chromatography on silica gel, Sephadex LH-20 and semi-preparative HPLC.  Its structure and stereochemistry was established on the basis of HR-ESI-MS, 1D and 2D NMR spectroscopic methods.  The NMR spectrum showed this compound exists in solution as a mixture of two stereoisomers.  The cytotoxic effect of compound 1 was evaluated in A-549, HL-60, HeLa, and K562 cancer cell lines.  However, compound 1 only displayed weak cytotoxic activity on HL-60 cell, with IC₅₀ value 77.4 μmol·L⁻¹.