Abstract: Object: To provide a thermostable L-ribose isomerase. Means for Resolution: The thermostable L-ribose isomerase with MW. 32,000 (by SDS-PAGE), optimal temperature of 45° C., optimal pH of pH 9.0 (glycine-NaOH buffer), and stable physicochemical properties such as temperature stability up to 45° C. during thermal treatment at pH 9.0 for 10 minutes, and with an action to isomerize L-ribose to generate L-ribulose or of inversely to isomerize L-ribulose to generate L-ribose.

Abstract: A reduction inhibitory agent for active oxygen eliminating activity which comprises cyclotetrasaccharide i.e., cyclo{6}-?-D-glucopyranosyl-(1 3)-?-D-glucopyranosyl-(1 6)-?-D-glucopyranosyl-(1 3)-?-D-glucopyranosyl-(1), as an effective ingredient, a method for inhibiting the reduction of active oxygen eliminating activity which comprises incorporating either cyclotetrasaccharide or the reduction inhibitory agent into plant edible products and/or plant antioxidants, and a composition where the reduction of active oxygen eliminating activity of the plant edible products and/or plant antioxidants has been satisfactorily inhibited by the method.

Abstract: Lactic acid and its derivatives such as D-lactic acid, L-lactic acid, DL-lactic acid, and their nonmetallic derivatives and lactates of alkali metal or alkaline earth metal exhibit a strong skin-whitening effect at a concentration of 5 w/w % or higher in pigment cell. The skin-whitening effect is augmented by unsaturated fatty acids having a carbon number of 12-22.