Isolation, identification, and evaluation of biological activities of Daldinia eschscholtzii, an endophytic fungus isolated from the leaves of Musa paradisiaca

Abstract

Fungal endophytes of medicinal plants are gaining interest in the prospecting for biorelevant molecules due to their capacity to contribute novel compounds. This study was designed to identify and evaluate secondary metabolites of Daldinia eschscholtzii isolated from leaves of Musa paradisiaca for biorelevance. Plant leaves collection, fungal isolation, molecular identification, fermentation, and extraction of secondary metabolites were carried out following standard procedures. The crude extract was tested for antimicrobial, antioxidant, cytotoxic and antiviral properties; and further analyzed for their phyto-constituents using High performance liquid chromatography – diode array detection (HPLC-DAD).  At 1000 µg/ml, D. eschscholtzii extract exhibited antibacterial activity against Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli producing IZD of 3 mm, 5 mm, and 7 mm respectively, but showed no antifungal activity. It showed antioxidant activity in the DPPH free radical scavenging assay producing an inhibition of 65.9% at a concentration of 500 µg/mL. At a concentration of 10 µg/mL, the D. eschscholtzii extract showed weak cytotoxic activity against L5178Y mouse lymphoma cells with growth inhibitions of 17.4% but showed a robust inhibition of HIV-1 reverse transcriptase activity of 97 % at 250 µg/mL. HPLC analysis of the extract/fraction revealed the presence of four bioactive compounds: aureonitol, pestalotiolactone A, cyclopenol, and palitantin. The detection of these metabolites further confirms the potentials of these endophytes as possible sources of bioactive molecules.