Bioactivity evaluation of organic solvent extractions of Ganoderma lucidum: a Sri Lankan basidiomycete

In this study, bioactivities of organic solvent extracts derived from nine species of terrestrial fungi were evaluated. The methanol extract of Ganoderma lucidum was selected as a potent sample with antibacterial activity showing growth inhibitory effects against pathogenic bacterial strains. Solvent-solvent partition chromatography was used to seperate four fractions from the G. lucidum crude sample. Among the fractions, chloroform fraction was proved to comprise seven major compounds in HPLC analysis. The positive peak 4, at 27.0 min retention time on the UV detector at 290 and 365 urn, which corresponded to the negative, peak at 680 nm on-line HPLC-ABTS(+) chromatogram was identified as an antioxidant compound. Antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) was tested using radical scavenging activity with the electron spin resonance spectrometer (ESR). The highest activity was shown by the chloroform fraction with a IC50 value 0.684 +/- 0.31 mg mL(-1). The inhibitory effect of nitric oxide (NO) production (%) was reported as the highest with the IC50 value 30.38 +/- 0.03 mu g mL(-1) from chloroform fraction against lipopolysaccharide (LPS) induced RAW 264.7 cells in vitro. The methanol and ethyl acetate fractions also showed similar but lesser effects with IC50 values 33.09 +/- 0.04 and 122.9 +/- 0.82 mu g mL(-1), respectively. Cell viability (%) by the MTT assay confirmed that there was no cytotoxic effect when treated with G. lucidum extracts at all concentrations. These results demonstrate the potential of using chloroform extracts of G. lucidum in antibacterial, antioxidant and anti-inflammatory therapeutic applications.