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

Yao-Yao Zheng,Nan-Xing Shen,Zhao-Yang Liang,Min Chen,Chang-Yun Wang,Xiu-Mei Fu,Xiao-Jian Zhou,Wen-Long Liu

doi:10.3390/md17060322

Abstract

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.

Highlights

Natural marine products have been recognized as a valuable and excellent source of structurally novel pharmaceuticals
Comparing the antibacterial tested bacterial the antibacterial the monomeric compounds activities of the monomeric compounds (1–3) and the two dimers, the results suggest that the dimeric forms decrease the antibacterial activity
The results showed that compound 3 exhibited significant antifungal activities against the four tested crop pathogens (Table 3), especially against the rice sheath blight pathogen R. solani

Summary

Introduction

Natural marine products have been recognized as a valuable and excellent source of structurally novel pharmaceuticals. Marine-derived microorganisms, especially mangrove-associated microorganisms, have developed distinctive metabolic mechanisms on account of the unique properties of the marine environment and their specific functions in the ecosystem, providing a lot of structurally diverse secondary metabolites with a wide variety of biological activities. Mangrove-derived fungi have become one of the research hotspots in the area of natural products and marine drugs [1,2,3,4,5,6], with a steady and continued growth in the number of new metabolites, from 108 in 2014 and 126 in 2015 to 142 in 2016 [7]. Mar. Drugs 2019, 17, 322; doi:10.3390/md17060322 www.mdpi.com/journal/marinedrugs.

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