Marine melanin: Antioxidant and radio protective properties

Abstract

Marine biopolymers are attracting a great deal of attention owing to their distinct bioactive properties. Among marine biopolymers, melanin is unique in several aspects, as it has many functional sites, which makes it suitable for varied types of industrial applications. Melanin was isolated from cuttlefish ink and modified for specific applications. Scanning electron microscopic image of native melanin indicated granules of melanin confined within melanosome vesicles. The solubility profile of purified melanin revealed distinct settling behaviour at acidic pH, colloidal behaviour at neutral pH, and complete solubilisation above pH 8.5. Isolated melanin showed broad spectral absorption in the entire UV range with a narrow and lower absorption at around 800 nm. FTIR spectra showed characteristic peaks of OH, NH, and antioxidant phenolic groups of melanin pigment. Elemental composition of melanin was found to be identical to human skin melanin. The antioxidant properties of melanin using invitro model assays indicated higher antioxidant power compared to BHA and BHT. Hence, antioxidant efficacy was further ascertained in a model vegetable oil system, under accelerated storage environment. The results indicted better oxidative protection at 0.5%, as confirmed by fatty acid profile and lower FFA, PV and TBARS values. Oil containing 1 per cent melanin showed similar oxidative progress as that of control samples, during storage. In brief, the results of present study identifies marine melanin as a prospective photoprotective and anti-oxidative moiety suitable for incorporation in cosmetic and food formulations.