Isolation, structure elucidation and apoptosis-inducing activity of new compounds from the edible fungus Lentinus striguellus.

Three new natural compounds, striguellolide A (1), striguellol A (2) and striguellone A (6), together with three known ones, 3,4-trans-dihydroxy-6-methoxy-2,2-dimethylchroman (3), 3-hydroxy-6- methoxy-2,2-dimethylchroman-4-one (4) and 3-hydroxy-6- methoxy-2,2-dimethylchroman (5), were isolated from the agar cultures of the edible fungal strain Lentinus striguellus. Their structures were elucidated by spectroscopic and mass spectrometric analyses, including 1D-, 2D-NMR and HR-ESI-Q-TOF-MS, and chemical reactions. Striguellone A showed cytotoxicity against HeLa cells by MTT assay and was found to be an activator of apoptosis, assessed by morphological observation and cell cycle analysis using the flow cytometer.