BACKGROUND: The microbes living in planta termed ‘endophytes’ is bestowed with the potential to produce bioactive substances. The aim of this investigation was focused on the isolation and molecular identification of the fungal endophytes fromZingiber nimmonii (J. Graham) Dalzell., an endemic medicinal plant species of the ‘Western ghats’, a hotspot location in southern India and characterization of the secondary metabolites responsible for the antioxidant and DNA protective capacity using chromatography and mass spectrometry techniques.

METHODS: Endophytic fungi were isolated and identified by sequencing the Internal Transcribed Spacer (ITS). The secondary metabolites were extracted with ethyl acetate and evaluated for the total phenolic, flavonoid and antioxidant capacities. The isolates with potential antioxidative property were further analyzed for the DNA protection ability and the presence of bioactive phenolic compounds by High Performance Liquid Chromatography (HPLC) and Electrospray Ionization-Mass Spectroscopy/Mass Spectroscopy (ESI-MS/MS) techniques.

RESULTS: Endophytic fungi belonging to 11 different taxa were identified. The total phenolic content of the extracts ranged from 10.8±0.7 to 81.6±6.0 mg gallic acid equivalent/g dry extract. Flavonoid was present in eight extracts in the range of 5.2±0.5 to 24.3±0.9 mg catechin equivalents/g dry extract.Bipolaris specifera, Alternaria tenuissima, Aspergillus terreus, Nectria haematococca and Fusarium chlamydosporum extracts exhibited a potentially high antioxidant capacity. Characterization of the extracts revealed an array of phenolic acids and flavonoids.N. haematococcaand F. chlamydosporum extracts contained quercetin and showed DNA protection ability.

CONCLUSION: This study is the first comprehensive report on the fungal endophytes from Z. nimmonii, as potential sources of antioxidative and DNA protective compounds. The study indicates that Z. nimmonii endophytes are potential sources of antioxidants over the plant itself.