Bioassay-guided fractionation and identification of active substances from the fungus Aspergillus tubingensis against Vibrio anguillarum

ABSTRACT

The aim of this study was to perform bioassay-guided fractionation and identification of active substances against the aquatic pathogen Vibrio anguillarum from the fungus Aspergillus tubingensis SZX-6 associated with the crab Portunus trituberculatus. Based on the antibacterial activity against V. anguillarum, three compounds were isolated and purified from the culture broth of strain SZX-6 by sequential column chromatography over silica gel, Sephadex LH-20 and RP-18. The isolated compounds were identified on the basis of extensive spectroscopic data analysis. They were methyl 6-acetyl-5,7,8-trihydroxy-4-methoxy-2-naphthoate (1), daidzein (2) and genistein (3). Compound 1 showed moderate antibacterial activity against V. anguillarum (minimum inhibitory concentration 0.063 mg/mL). The obtained results could serve as a basis for further research towards design of active antibacterial agents against aquatic pathogens.

KEYWORDS:

• Marine-derived fungi; Aspergillus tubingensis
• antibacterial activity
• Vibrio anguillarum
• fractionation and identification

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Open Research Fund Program of the Key Laboratory of Marine Drugs (Ocean University of China), Ministry of Education [grant number KLMD(OUC)201302]; the Key Laboratory of Marine Bioactive Substances and Modern Analytical Techniques, SOA [grant number MBSMAT-2013-04]; Jiangsu Key Laboratory of Marine Biotechnology, Huaihai Institute of Technology [grant number 2014HS006]; the Natural Science Foundation of Jiangsu Province [grant number BK20151283]; Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) [grant number 5511201401X].