Elsevier

Tetrahedron Letters

Volume 58, Issue 12, 22 March 2017, Pages 1151-1155
Tetrahedron Letters

Antiviral peptides from marine gorgonian-derived fungus Aspergillus sp. SCSIO 41501

https://doi.org/10.1016/j.tetlet.2017.02.005Get rights and content

Highlights

Abstract

A new cyclic pentapeptide and three new linear peptides, namely, aspergillipeptides D–G (14), were isolated from a culture broth of marine gorgonian-derived fungus Aspergillus sp. SCSIO 41501. Their structures were elucidated by spectroscopic analysis, and their absolute configurations were confirmed by Marfey’s method. Compounds 1 and 2 showed evident antiviral activity against herpes simplex virus type 1 (HSV-1) with IC50 values of 9.5 and 19.8 µM under their non-cytotoxic concentrations against a Vero cell line, respectively, and 1 also had antiviral activity against acyclovir-resistant clinical isolates of HSV-1.

Introduction

Marine peptides have been obtained from algae, fish, mollusk, crustacean, crab and marine bacteria and fungi. Bioactive marine peptides based on their structural properties, amino acid composition and sequences have been shown to display a variety of bioactivities such as anti-tumor, antiviral, anticoagulant, antioxidant, immunoinflammatory effects, and other medicinal properties.1, 2, 3 In particular, studies evaluating the anti-infective actions of marine peptides are attracting increased researchers’ interest, and marine peptides have been increasingly considered as anti-infective drugs.1 In our previous study, we have ever obtained three cyclic tetrapeptides (namely, aspergilluipepetides A-C) from the fungal strain Aspergillus sp. SCSGAF 0076 (now re-numbered as SCSIO 41501) isolated from the China South Sea gorgonian Melitodes squamata.4 In order to obtain more new peptides from the strain, we raised the concentration of l-tryptophan from 0.05% to 0.2% in the basic culture medium, which led to the obtainment of a new cyclic pentapepetide and three new linear peptides, namely, aspergillipeptides D–G (14). Antiviral activities against HSV-1 of 14 were also evaluated. In this paper, we describe the isolation, structure elucidation, and antiviral activity of 14.

Section snippets

Results and discussion

The marine-derived fungal strain Aspergillus sp. SCSGAF 0076 was inoculated in liquid medium under static condition and finally harvested and extracted with EtOAc to gain the crude extract. The crude was separated by chromatographic techniques containing silica gel column, Sephadex LH-20, and preparative HPLC to yield compounds 14.

Compound 1 was obtained as a white solid. Its molecular formula was determined to be C40H49N5O8 on the base of its HRESIMS (m/z 728.3680 [M+H]+) requiring 19 degrees

General experimental procedures

UV spectra were obtained using a Shimadzu UV-1750 spectrophotometer. 1H, 13C NMR and 2D NMR spectra were recorded on a Bruker AV-500 MHz NMR spectrometer with TMS as internal standard. IR spectra were got on a Shimadzu IR Affinity-1. Optical rotations were measured with a Perkin Elmer 341 polarimeter. HRESIMS spectra were obtained on a Bruker LC-20AT-QII mass spectrometer. Preparative HPLC was operated on a Shimadzu LC-20AT pump with a Shimadzu SPD-M20A Photodiode Array Detector using an

Acknowledgment

We are grateful for the financial support provided by the Natural Science Foundation of China (81673326 and 41376160), Strategic Leading Special Science and Technology Program of Chinese Academy of Sciences (XDA100304002), Regional Innovation Demonstration Project of Guangdong Province Marine Economic Development (GD2012-D01-002), and National Marine Public Welfare Research Project of China (201305017).

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