Diversity and bioactivity of endophytic fungi from Nothapodyte foetida (Wt.) sleumer and Hypericum mysorense heyne

Abstract

Endophytic fungi were isolated from the medicinal plants Nothapodyte foetida and Hypericum mysorense, collected from the cold peaks of the Western Ghats of India, which is considered as one among ten important biodiversity hotspots of the world. The diversity of foliar endophytic biota in both plants was assessed using various indices. Endophytes were screened for the antimicrobial and free radical-scavenging activity. Ethyl acetate extracts of the culture broths of two isolates Bionectria ochroleuca NOTL33 from N. foetida and Chaetomium globosum HYML55 from H. mysorense were further characterized for their composition and minimum inhibitory concentrations (MIC) based on their significant activities during primary screening. MIC of both extracts ranged from 78 to 625 μg/ml, with the exception of Pseudomonas aeruginosa (5 mg/ml). 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radical quenching by the extracts were dose dependent. 2-heptanone, furfural, methyl furfural, benzyl pentyl ketone, benzyl decanoate, amyl isovalerate and palmitic acid were identified in NOTL33 extract by gas chromatography– mass spectrometry (GC-MS) analysis. A yellow amorphous powder (HYML 8A) was purified from HYML55 extract and further characterized for MIC and minimum cidal concentrations against the test bacteria. The yield of the compound in different media was estimated.