Stevia rebaudiana accumulates more than 10 steviol glycosides in varying concentrations, depending on the genotype and cultivation conditions. Amounts of total steviol glycosides up to 20% of the dry leaf weight are reported.¹  The best known steviol glycosides are stevioside and rebaudioside A, which have the highest content in the plant (see Figure 4.1 and Table 4.1).

The analysis of steviol glycosides started in 1931 with the synthesis of stevioside described by Bridel and Lavieille elucidating the chemical formula of stevioside.²  Some decades later, stevioside, rebaudioside A, B, C, D and E and dulcoside A could be identified.^3–7  Since then, many minor steviol glycosides have been detected. To date, more than 40 different steviol glycosides have been described, which are diterpenes based on the ent-kaur-16-en-19-oic acid skeleton and are bound to different sugar moieties at the C-13 and C-19 position (Figure 4.1).^8–10  They are divided into five groups, the glucosyl-, rhamnosyl-, xylosyl-, fructosyl- and deoxyglucose steviol family based on the type of glycosidic residues present. For example, stevioside and rebaudioside A belong to the glycosyl-family. Furthermore, several steviol glycosides have been isolated from commercially available stevia leaf extract with modification in the ent-kaurene skeleton. Ent-kaur-15-en-19-oic acid, 16ß-hydroxy-ent-kauran-19-oic acid and 13-methyl-16-oxo-17-nor-ent-kauran-19-oic acid have been classified as modified backbone.