Feasibility of sterilizing traditional Chinese medicines by gamma-irradiation

The feasibility of sterilizing traditional Chinese medicines (TCMs) by gamma-irradiation has been systematically evaluated by the biological, toxicological and physicochemical tests on irradiated hundreds of TCMs. Those TCMs investigated in general show no significant biological or toxicological changes after irradiation, yet physicochemical changes are detectable in some irradiated TCMs, and water in TCMs enhances the effects. Those results obtained from radiolysis of some major effective components of TCMs in aqueous or ethanolic solutions reveal that the site selection of radiolytically generated radicals follows the example of simple compounds with same function groups. Wholesomeness and chemical clearance present a bright future to sterilizing TCMs by gamma irradiation, however, some important measures and steps should be adopted: (1) The producers must strictly execute manufacturing procedure to reduce microbiological contamination thus lower the applied dose for sterilization which is recommended to be controlled under 5, 7 or 10 kGy. 10 kGy for dry herb, 7 kGy for herbal medicine and 5 kGy for some special herbal medicine; (2) Herb to be sterilized by gamma-irradiation should exist in possible dry state; (3) Powder TCMs is recommended to mix with honey forming bolus, which can minimize the decomposition of herb.