Effects of irradiation on decolourisation and biological activity in Schizandra chinensis extracts

The fruit of Schizandra chinensis Baillon is a well-known traditional medicinal plant in Korea, China and Japan. We examined the effects of gamma irradiation on decolourisation and biological activity of S. chinensis fruit extracts to facilitate industrial applications. Samples were exposed to gamma-ray irradiation from 0.5 to 10 kGy. Irradiation of greater than 2 kGy markedly reduced the major colourant in S. chinensis fruit extracts, cyanidin-3-O-xylosylrutinoside (Cya-3-O-xylrut), by 80–90%. Biological activities, such as radical-scavenging activity and elastase inhibition activity, were not affected by gamma irradiation, but we observed a 12.3% increase in tyrosinase inhibition activity. There were negligible changes in the amounts of the major lignans schizandrin, gomisin A and gomisin N, following irradiation. These results indicated that gamma irradiation can selectively remove undesirable colour in S. chinensis extracts without adverse changes in biological activity.