Isochroman and isocoumarin derivatives from hypersaline lake sediment-derived fungus Penicillium sp.

Chromatographic analysis of the ethyl acetate extract of the fungus Penicillium sp., which was isolated from the sediment of the hyper saline lake Wadi El-Natrun in Egypt, afforded two new isochromans ( 1 and 2 ) and a new isocoumarin derivative ( 3 ), along with six known compounds ( 4 – 9 ). The planar structures of new compounds were unequivocally elucidated on the basis of extensive 1D- and 2D-NMR spectroscopy as well as HRESIMS. The relative configurations of the new compounds were established by analysis of the coupling constants as well as through ROESY experiments, while the absolute configurations were determined by comparison of the [ α ] D values and by plausible biosynthetic considerations. Compounds ( 1 – 6 ) were found to share (3 S ) configuration. All compounds demonstrated a weak to moderate cytotoxic activity against the murine lymphoma L5178Y cell line. [ABSTRACT FROM AUTHOR]