Antioxidant potential of pigments produced by halophilic archaea isolated from salt pans of India

Halophilic archaea are a unique group of microorganisms that are adapted to survive in hypersaline econiches. In the present study two haloarchae strains isolated from salt pans were selected and checked for production of pigments and antioxidant activity. Haloarcula sp. E2 and Halorubrum sp. M5 produced a characteristic bright orange pigment when grown on moderate halophilic medium (MHM) (17% NaCl) and extremely halophilic medium (EHM) (25% NaCl) respectively. The orange pigments were extracted and characterized by thin layer chromatography (TLC), reversed phase high performance liquid chromatography (RP HPLC), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and liquid chromatography-mass spectrometry (LCMS) techniques. Pigments were majorly C50 carotenoids, bacterioruberin (BR) and its derivatives. The pigment extracts exhibited radical scavenging property on evaluation by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and had a protective effect against oxidative stress induced by hydrogen peroxide (H 2 O 2 ) in skin keratinocytes, HaCaT cell lines comparable to that of Vitamin E.