Abstract

Ultraviolet (UV) light tends to cause skin damage; melanin can scavenge reactive oxygen species (ROS) produced from UV to protect skin from damage caused by free radicals. The purpose of this study was to investigate the physico-chemical properties and antioxidant activity of extracted melanins. Melanins were extracted from black tea (BT-melanin), black soybean (BS-melanin) and black-bone silky fowl (SF-melanin); they were then compared with synthetic melanin (SY-melanin). Three kinds of extracted melanins have absorbance ability in broad-spectrum (190-450 nm) wavelength. The experiment’s results indicated that the solubility in 25? water, organic solvents, 1 M NH₄OH, and 1 M HCl of the three extracted melanins was similar to the solubility of synthetic melanin. The melanins also showed good stability in various light sources. The extracted melanins could chelate with Fe²⁺ and Cu²⁺. An in vitro study showed that the extracted melanin enhanced the survivability of fibroblast cells with 25 ?g mL^-1 concentration after UV irradiation (254 nm, 0.09 mW cm^{2 -1}) (p<0.05). All of the extracted melanins increased glutathione peroxidase (GSH-Px) and catalase activity when exposed to UV light (p<0.001). They inhibited the peroxidation of lipid (TBARS) and scavenged superoxide anion (p<0.001) induced by UV irradiation. According to the above results, the melanins extracted from black tea, black soybean, and black-bone silky fowl are similar in their physico-chemical properties, and they have the capacity for anti-oxidation and photoprotection from UV irradiation.

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