UPLC–MS and Dereplication-Based Identification of Metabolites in Antifungal Extracts of Fungal Endophytes

Abstract

Microbial biopesticides offer an eco-friendly alternative to synthetic chemical pesticides. Bioassay-guided fractionation of ethyl acetate concentrate of two fungal endophytes Setosphaeria rostrata (NCBI accession no. KR017047) and Acremonium sp. (NCBI accession no. KT428769) isolated from medicinal plants Chlorophytum borivilianum and Mentha piperita, respectively, was done in this study. These two isolates exhibited strong antifungal activities (IC50 value < 1 mg/ml) towards economically relevant phytopathogens, i.e. Sclerotinia sclerotiorum, Fusarium oxysporum, Botrytis cinerea and Rhizoctonia solani. Ethyl acetate extracts were subjected to MPLC to obtain fractions for metabolite identification. Bioactive components in the fractions were exhaustively characterised by aggressive dereplication based on accurate mass in UPLC–MS using online METLIN database. Systematically demarcated chromatographic and hyphenated spectroscopic techniques led to the identification of the well-described antifungal metabolite sulphamethazine (sulphonamide derivative). The study highlights the significance of dereplication procedure for probable identification of bioactive metabolites.