Mutagenic tests of stevioside and steviol

Abstract

The mutagenicity of stevioside, a constituent of Stevia rebauaians, and steviol, the aglycone of stevio-sice, was determined by Ames test using TA98 and TA 100 and forward mutation test using TM 677 tester strain of S.typhimurium. No mutagenic activity of stevioside (at a concentration as high as 29 mg/plate) by using both TA 98 and TA 100 with and without S-9 fractionsfromlivers of rats, mice, hamsters, guinea pig and rabbits treated with polychlorinated giphenyl (PCB) was deteted. Additionally, stevioside (20 mg/ml) could not induce mutation in forward mutation using TM 677 with and without S-9 fractions from livers of the rats treated with PCB. However, the mutagenic activity of steviol (0.1-5 mg/ml) was detected only in forward mutation test using TM 677, when evaluated in the presence of S-9 fractions from livers of all animal species including rats, mice, guinea pigs, hamsters and rabbits. But not in Ames test musing TA 98 and TA 100. It is therefore demonstrated that steviol has to be metabolized to active metabolits which is capable of inducing mutation in only forward mutation test.