Antimicrobial activity of n-hexane and ethyl acetate extracts from Candida tropicalis and Phyllosticta capitalensis fungal endophytes

Abstract

Background ad objective: Among the notable achievements of the twentieth century was the discovery and identification of new drugs from plants against microbial infections. However, the discovery of novel drugs since then is inadequate due to emergence of resistant microbes. In an effort to discover novel drugs, the study aimed to investigate the antimicrobial activity of crude extracts from endophytic fungi isolated from Cnidoscolas aconitifolius and Ocimum suave. Methods: Following morphological characterization and initial screening for antimicrobial activity, isolates that had higher inhibition were genotypes by Sanger sequencing. Two isolates (Candida tropicalis from O. suave and Phyllosticta capitalensis from C. aconitifolius) were tested for antimicrobial activity against Escherichia coli and Staphylococcus aureus. Results: Overall, the range of crude extract concentration was from 152 mg/mL to 1353 mg/mL, and that of a zone of inhibition was from 7 to 21 mm. The lowest minimum inhibition concentration (19>MIC>9.5) was observed in Phyllosticta spp. extract against S. aureus. Conclusions: Findings of the present study have shown that endophytes isolated from medicinal plants can generate secondary metabolites with therapeutic applications. Therefore, further investigations are warranted to decipher the content and structure of bioactive compounds that may be associated with the antimicrobial activity of crude extracts.