Antibacterial and antioxidant activities of endophytic fungi extracts of medicinal plants from Central Sulawesi

Abstract

Endophytic fungi are a group of fungi which grow inside the plant tissues without causing negative symptoms to the host plant and are able to produce biologically active substances. This research was carried out to evaluate the antibacterial and antioxidant activity of 40 endophytic fungi isolated from 10 species of medicinal plants collected from Palolo, Central Sulawesi. Thin layer chromatography (TLC) bioautography guided screenings were done to evaluate antibacterial and antioxidant activities. The antibacterial activity was done against Staphylococcus aureus InaCC-B5 and Escherichia coli InaCC-B4, while antioxidant activity was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Minimum inhibitory concentrations (MICs) of active extracts were further evaluated against these bacteria, while half-maximal inhibitory concentration (IC50) of active extracts was determined by the microdilution broth method. The results of TLC bioautography screening showed 30 extracts inhibited the growth of S. aureus, 29 extracts inhibited the growth of E. coli, 27 extracts inhibited both S. aureus and E. coli, and 23 extracts posessed antioxidant activity. There were six extracts with MIC value of < 100 μg/ml against S. aureus and nine extracts with MIC value of < 100 μg/ml against E. coli. Six extracts indicated very strong antioxidant activity.