Stevioside structure

Mosettig and Ness determined that steviol and isosteviol were diterpenoid acids with the former containing a 2,11-cyclopentanoperhydro-phenanthrene skeleton, a hydroxyl acid and a terminal methylene group. It was in 1963 that Mosettig and his colleagues finally showed the unambiguous structure of stevioside. 

Mosettig E, Ness WR, Stevioside. If. The structure of the aglucon. / Org Chem... 

The leaves of Rubus smvissimus S. Lee (Rosaceae), which is found wild in Guang Xi province in China, show potent sweetness and are used as a drink (sweet tea tian-cha). Rubusoside has been isolated as a major sweet component from the leaves.28 This compound has the same aglycon structure as stevioside but with one glucose less and can be obtained from stevioside by enzymatic transformation. Rubusoside is 130 times sweeter than sucrose. A comprehensive review of stevioside has been published.29... 

Fig.(l). Structures of stevioside and related compounds. In rebaudioside A, B, C, D and E an additional sugar moiety is added on earbon 3 of the first pGlc. 

The following examples show the versatility of the Beckmann reaction in the formation of novel structures by exploring the ent-kaurene skeleton of stevioside. 

Figure 4A.21 Steviarebaudiana. (a) Stevia plant (b) Stevia field (Picture (a) and (b) Foundation of Humanity and Development "F.H.D." Guido Herrera, with kind permission) (c) Dry leaves of Stevia rebaudiana (d) chemical structure Stevioside (e) chemical structure Steviol (f) chemical structure Rebaudioside A.

Leaves of Stevia rebaudiana contain approx. 6% stevioside (/sac, g(4) 300). Its structure is shown in Formula 8.7. This compound is of interest as a sweetener, however its toxic properties are unclear. 

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