The present invention relates to a novel compound having excellent antioxidant activity, isolated from Ramalina terebrata, and more particularly to a novel compound, RAMALIN™, having excellent antioxidant activity, isolated from the Antarctic lichen Ramalina terebrata, a method for preparing the RAMALIN™, and a pharmaceutical composition, a functional food and a functional cosmetic composition, which contain the RAMALIN™ as an active ingredient. The RAMALIN™ according to the invention has significantly excellent antioxidant effects compared to commercially available antioxidants, and thus can be widely used in agents for treating oxidation-related diseases, anti-aging functional foods, functional cosmetic products for skin whitening and wrinkle reduction, etc.
