Lentinoids A–D, New Natural Products Isolated from Lentinus strigellus

Four novel lentinoids (1–4), along with the known compounds striguellone A (5), isopanepoxydone (6) and panepoxydone (7), were isolated as part of our studies on Lentinus strigellus. The structures of 1–4 have been established by 1D- and 2D-NMR and MS analysis. Compounds (1–3) and (5–7) were tested against Listeria monocytogenes, Enterococcus faecalis, Pseudomonas aeruginosa and Klebsiella pneumoniae. These compounds showed inhibition diameters ranging from 7.5–9.5 mm, however, when the minimum inhibitory concentration (MIC) was determined, only compound 1 showed a significant activity of 200 μg/mL. Intermediates for the biosynthesis of the oxygenated cyclohexenyl derivatives isolated from lentinoid fungi (genera Lentinus and Panus) are proposed.