Antimicrobial Assay and GC-MS Profile of the Extract of the Endophytic Fungus from <i>Annona muricata</i> (Annonaceae) Leaf

Abstract

Emerging cases of antimicrobial resistance in the treatment of microbial infections have really posed as a threat thus leading to the search of new drugs from natural sources. Endophytic fungi which live within plant's cells are microorganisms from which many novel metabolites with antimicrobial activity can be obtained. The aim of the study was to examine the antimicrobial activity and the phytoconstituents of the extract produced by the endophytic fungus from Annona muricata. From A. muricata leaves, the fungal endophyte was extracted and fermented. The endophytic extract produced was tested against Pseudomonas aeruginosa, Streptococcus mutants, Salmonella typhi, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Aspergillus niger, and Candida albicans. Following standard protocols, the extract was screened for phytochemicals and subjected to GC-MS analysis. With the exception of P. aeruginosa and A. niger, the results demonstrated that the extract has antimicrobial property with minimum inhibitory concentration (MIC) values in the range of 0.8 mg/ml to 1.0 mg/ml. Phytochemicals tested including phenolics, flavonoids, alkaloids, tannins, steroids, saponins and terpenes were present. Twenty (20) main compounds, mostly fatty acids, were detected by GC-MS and they may be the source of the extract's antimicrobial property. The endophytic fungus extract possesses significant bioactive compounds with a wide spectrum of antimicrobial activity and can be further explored.