Antimicrobial Meroterpenoids and Erythritol Derivatives Isolated from the Marine-Algal-Derived Endophytic Fungus <i>Penicillium chrysogenum</i> XNM-12

• Main Authors: Kuo Xu, Xu-Lun Wei, Lin Xue, Zhong-Feng Zhang, Peng Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Marine Drugs
• Subjects: algal; endophytic fungus; <i>Penicillium</i>; meroterpenoids; antimicrobial activity
• Online Access: https://www.mdpi.com/1660-3397/18/11/578

One new meroterpenoid-type alkaloid, oxalicine C (<b>1</b>), and two new erythritol derivatives, penicierythritols A (<b>6</b>) and B (<b>7</b>), together with four known meroterpenoids (<b>2</b>–<b>5</b>), were isolated from the marine algal-derived endophytic fungus <i>Penicillium chrysogenum</i> XNM-12. Their planar structures were determined by means of spectroscopic analyses, including UV, 1D and 2D NMR, and HRESIMS spectra. Their stereochemical configurations were established by comparing the experimental and calculated electronic circular dichroism (ECD) spectra for compound <b>1</b>, as well as by comparison of the optical rotations with literature data for compounds <b>6</b> and <b>7</b>. Notably, oxalicine C (<b>1</b>) represents the first example of an oxalicine alkaloid with a cleaved α-pyrone ring, whereas penicierythritols A (<b>6</b>) and B (<b>7</b>) are the first reported from the <i>Penicillium</i> species. The antimicrobial activities of compounds <b>1</b>–<b>7</b> were evaluated. Compounds <b>1</b> and <b>6</b> exhibited moderate antibacterial effects against the plant pathogen <i>Ralstonia solanacearum</i> with minimum inhibitory concentration (MIC) values of 8 and 4 μg/mL, respectively. Compound <b>6</b> also possesses moderate antifungal properties against the plant pathogen <i>Alternaria alternata</i> with a MIC value of 8 μg/mL.