New Naphtho-γ-Pyrones Isolated from Marine-Derived Fungus Penicillium sp. HK1-22 and Their Antimicrobial Activities

摘要

Three novel monomeric naphtho-γ-pyrones, peninaphones A–C (compounds >1–>3), along with two known bis-naphtho-γ-pyrones (compounds >4 and >5) were isolated from mangrove rhizosphere soil-derived fungus Penicillium sp. HK1-22. The absolute configurations of compounds >1 and >2 were determined by electronic circular dichroism (ECD) spectra, and the structure of compound >3 was confirmed by single-crystal X-ray diffraction analysis. Compounds >4 and >5 are a pair of hindered rotation isomers. A hypothetical biosynthetic pathway for the isolated monomeric and dimeric naphtho-γ-pyrones is also discussed in this study. Compounds >1–>3 showed antibacterial activity against Staphylococcus aureus (ATCC 43300, 33591, 29213, and 25923) with minimum inhibitory concentration (MIC) values in the range of 12.5–50 μg/mL. Compound >3 exhibited significant activity against the rice sheath blight pathogen Rhizoctonia solani.