Digestion of stevioside, a natural sweetener, by various digestive enzymes

In vitro digestibility of stevioside, a natural sweetener, by various digestive enzymes was investigated. Stevioside was incubated with salivary alpha-amylase, pancreatic alpha-amylase, saliva, pepsin, gastric secretion, pancreatin and intestinal brush border membrane enzymes of mice, rats, and hamsters as well as with intestinal microflora of mice, rats, hamsters and humans. None of these enzymes digested stevioside except the microflora of the rat and hamster cecal contents, which hydrolyzed it to steviol, and the microflora of mouse cecal content and human feces, which hydrolyzed it to both steviol and steviol-16,17 alpha-epoxide. Steviol16,17 alpha-epoxide was then completely converted back into steviol. These results suggest that steviol might be the only metabolite produced by the intestinal microflora from various animal species and humans.