Antimicrobial Meroterpenoids and Erythritol Derivatives Isolated from the Marine-Algal-Derived Endophytic Fungus Penicillium chrysogenum XNM-12.

Kuo Xu,Peng Zhang,Zhong-Feng Zhang,Xu-Lun Wei,Lin Xue

doi:10.3390/md18110578

Abstract

One new meroterpenoid-type alkaloid, oxalicine C (1), and two new erythritol derivatives, penicierythritols A (6) and B (7), together with four known meroterpenoids (2–5), were isolated from the marine algal-derived endophytic fungus Penicillium chrysogenum 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 1, as well as by comparison of the optical rotations with literature data for compounds 6 and 7. Notably, oxalicine C (1) represents the first example of an oxalicine alkaloid with a cleaved α-pyrone ring, whereas penicierythritols A (6) and B (7) are the first reported from the Penicillium species. The antimicrobial activities of compounds 1–7 were evaluated. Compounds 1 and 6 exhibited moderate antibacterial effects against the plant pathogen Ralstonia solanacearum with minimum inhibitory concentration (MIC) values of 8 and 4 μg/mL, respectively. Compound 6 also possesses moderate antifungal properties against the plant pathogen Alternaria alternata with a MIC value of 8 μg/mL.

Highlights

Fungal secondary metabolites of marine origin have drawn considerable attention because of their unique chemical structures and potential pharmaceutical applications [1,2,3]
The 1 H NMR spectrum (Table 1) revealed four signals that resonated at δH 8.89 (1H, s, H-2), 8.14 (1H, d, J = 8.0 Hz, H-4), 7.50 (1H, m, H-5), and 8.66 (1H, d, J = 4.5 Hz, H-6), which are typical of a two-substituted pyridine moiety [14,15,16]
Penicillium species have played an important role in drug development throughout human history

Summary

Introduction

Fungal secondary metabolites of marine origin have drawn considerable attention because of their unique chemical structures and potential pharmaceutical applications [1,2,3]. Marine algae harbor a rich fungal endophyte community. These endophytes can harmoniously colonize the internal tissues of their hosts and produce bioactive secondary metabolites that protect their hosts in the interactional processes of symbiosis and evolution [10,11,12,13]. In our ongoing efforts to discover structurally unique and biologically active secondary metabolites from algal-derived endophytic fungi, the fungal strain Penicillium chrysogenum XNM-12 from the marine brown alga Leathesia nana (Chordariaceae) was chosen for further chemical investigation

Methods

Results

Conclusion