Effect of gamma irradiation on color characteristics and biological activities of ethanol extract of Lonicera japonica

Abstract

Effects of gamma irradiation on color characteristic and biological activities of ethanol extract of Lonicera japonica irradiated at 0, 10, 20, and 30 kGy were investigated. Hunter color L*- and a*-value increased by irradiation in a dose-dependent manner, resulting in lighter color than the nonirradiated, whereas Hunter color b*-value decreased with increasing irradiation dosage (p <0.05). The L. japonica extract showed inhibition effects against tyrosinase, xanthine oxidase, and nitrite-scavenging ability. Tyrosinase inhibition effect of L. japonica was higher in the gamma-irradiated sample than in the nonirradiated sample, and the effect was increased by increasing irradiation dosages. The L. japonica extracts had a higher inhibitory effect against xanthine oxidase, and the effect was not greatly changed by irradiation. Nitrite-scavenging activity was the highest in L. japonica extract at pH 1.2. Overall, the gamma irradiation may not greatly influence the xanthine oxidase inhibition effect and nitrite-scavenging ability of the L. japonica extract, except for the tyrosinase inhibition effect when irradiated up to 30 kGy.