Purification and toxicity studies of stevioside from Stevia rebaudiana Bertoni

The present study was undertaken to purify the stevioside from leaves of Stevia rebaudiana and to determine its toxicity effects. The accumulation of stevioside was found in all parts of the Stevia plant that is from ischolar_main to flowers with the highest content in mature leaves. A protocol has been standardized for the production of white stevioside powder from dried mature leaves of Stevia rebaudiana using water as solvent in the extraction and filtration procedures. The pigments and phenols in the crude extract were removed at the first step of processing. The depigmented extract was bleached and refined by celite treatment at the second level. The purity at each step was checked by HPLC using purified stevioside as standard. The end solution was spray dried into fine white stevioside powder. The final yield was estimated as 11.6%, which is equivalent to international standard. The protocol was found reliable and economical for the commercial production of stevioside as a natural sweetener. The method was filed for Indian patent no: 01436/CHE/2007. As a zero calorie natural sweetener with more potential application in the treatment of Type II diabetes, toxicological analysis of the product was done for revealing the acute oral toxicity and cytotoxicity of the product. In the oral toxicity test none of the animals showed any abnormal behaviour and all the organs were found physiologically normal at a higher dosage of 2000mg stevioside/kg bodyweight on feed trials suggesting the non-toxic nature of stevioside in rats. The in vitro cytotoxicity test has revealed the non cytotoxic property of stevioside at a concentration of 1.25g/L.