Hydroquinone derivatives from the marine-derived fungus Gliomastix sp.

Abstract

Eight new hydroquinone derivatives, gliomastins A–D (1–4), 9-O-methylgliomastin C (5), acremonin A 1-O-β-D-glucopyranoside (6), gliomastin E 1-O-β-D-glucopyranoside (7), and 6′-O-acetyl-isohomoarbutin (8), together with seven known analogues were isolated from the marine-derived fungus Gliomastix sp. Their structures were elucidated by extensive spectroscopic analysis including 1D and 2D NMR measurements aided by DFT NMR calculations as well as MS data. TDDFT-ECD and OR calculations were performed to determine the absolute configurations of 1 and the aglycones of 6 and 7. Compound 1 features a novel skeleton, biogenetically derived from a Diels–Alder reaction between derivatives of 11 and 13. Compound 2 represents a rare sulfur-containing alkaloid derived from the known hydroquinone 13. Compounds 1, 10 and 12 showed strong cytotoxicity against the L5178Y mouse lymphoma cell line with IC₅₀ values of 1.8, 1.0 and 1.1 μM, respectively. Compound 3 exhibited moderate antitubercular activity against Mycobacterium tuberculosis with a MIC value of 12.5 μM.