Hydroxydehydrostevic acid; 13-Hydroxykaurenoic acid; ent-13-Hydroxy-kauran-16-en-19-oic acid
3D model (JSmol)
|Molar mass||318.457 g·mol−1|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Steviol occurs in the plant as steviol glycosides, sweet compounds that have found widespread use as sugar substitutes. The aglycon is prepared by enzymatic hydrolysis, since upon acid treatment steviol will undergo Wagner-Meerwein rearrangement to the very stable isosteviol.
In Stevia rebaudiana, the biosynthesis of steviol is confined to green tissues. The precursors of steviol are synthesized via the non-mevalonate pathway located in plant cell plastids, which produces isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). IPP and DMAPP are converted to geranylgeranyl diphosphate (GGDP), which is the precursor of many diterpenoids, by GGDP synthase. GPDP is made into a cyclic compound, copalyl diphosphate (CDP), by CDP synthase, after which kaurene is produced by another cyclization catalyzed by kaurene synthase.
The kaurene is then transferred to the endoplasmic reticulum, where it is oxidized to kaurenoic acid by kaurene oxidase in a reaction that uses up oxygen and NADPH. Then steviol is produced by hydroxylation. The steviol is subsequently glycosylated in the cytoplasm.
- Bridel, M.; Lavieille, R. (1931). "The sweet principle in Kaa-he-e (Stevia rebaudiana. Bertoni). II. Hydrolysis of stevioside by enzymes. III. Steviol by enzymic hydrolysis and isosteviol by acid hydrolysis". Bulletin de la Société de Chimie Biologique. 13: 781–796.
- Dolder, Fred; Lichti, Heinz; Mosettig, Erich; Quitt, Peter (1960). "The structure and stereochemistry of steviol and isosteviol". Journal of the American Chemical Society. 82: 246–247. doi:10.1021/ja01486a054.
- J. E. Brandle, A. N. Starratt, M. Gijzen (1998), Stevia rebaudiana: Its agricultural, biological, and chemical properties. Canadian Journal of Plant Science, volume 78, issue 4, pages 527-536. doi:10.4141/P97-114
- Brandle JE, Telmer PG. Steviol glycoside biosynthesis. Phytochemistry. 2007 Jul;68(14):1855-63. PMID 17397883