Isolation and Neuroprotective Activity of Phenolic Derivatives from the Marine-Derived Fungus Penicillium janthinellum

A new phenolic compound, 6-(2-acetyl-3, 5-dihydroxybenzyl)-4-hydroxy-3-methyl-2H-pyran-2-one (1), along with other six known phenolic derivatives (2−7), were isolated from the mangrove rhizosphere fungus Penicillium janthinellum HK1-6 cultured in potato dextrose broth medium containing 30 g L⁻¹ of natural sea salt. The structure of the new compound (1) was elucidated by comprehensive analysis of spectroscopic data including 1D and 2D NMR spectra. The proposed biosynthetic pathway of compound 1 was also studied in this research. Interestingly, a brominated phenolic derivative, aryl bromide (compound 8), was obtained from this fungal strain cultured in medium containing 30 g L⁻¹ of NaBr instead of natural sea salt. Compound 8 is proposed as a new natural product and formed through bromination of compound 7 when the fungus was cultured with NaBr. The neuroprotective effect of compound 1 on oxygen-glucose deprivation (OGD)-induced injury was investigated in rat spinal cord astrocytes. MTT assay demonstrated that compound 1 can attenuate OGD-induced cell viability loss in rat spinal cord astrocytes.