Stevioside

Stevioside is used as a sweetener in Far Eastern markets and in some South American countries. It is extracted from the leaves of Stevia Rebaudiana 

Bertoni, a plant native to Paraguay and now commercially cultivated in Asia and South America. Several extracts from the Stevia plant ate available which contain different levels of stevioside and also other sweet compounds (rebau-diosides, dulcosides). This inconsistency of extracts is probably the reason much variation exists in the data about stevioside. 

Pure stevioside is a white hygroscopic powder (The Merck Index, 1976) and commercial extracts vary from cream to tan powders. The solubility of pure stevioside in water is 1.2 g/1 (The Merck Index, 1976). Commercial extracts have solubilities that range from 300 to 800 g/1 (Stevia Corporation, 1986). The relative sweetness of stevia extracts varies from 15 to 300 (O Donnell, 1983 Richard, 2002 Tunaley et al., 1987 ) The taste of stevioside is characterised by a lingering sweetness and liquorice, bitter off-taste (O Donnell, 1983). This limits its commercial application and it is generally not used as a sole sweetener in most applications. 

The metabolism of stevia and stevia extracts has been the subject of much discussion. The available data are inconsistent and it is unclear whether steviol, the aglycone portion of stevioside, is generated in the gut. Steviol produces a mutagen (Phillips, 1987). The generation of steviol has been demonstrated in vitro and in vivo in rats (Phillips, 1987). 

The regulatory position of stevioside varies in different regions of the world. Japan is the main market for stevioside and consumes 90% of the world s supply of stevia leaves (Richard, 2002). Stevioside is used in Japan in a variety of applications, including soft drinks. In other markets, the use of stevioside, if permitted at all, is limited to supplements. In the United States, the FDA issued an import alert in May 1991 blocking the import of and sale of stevia products, following the results of a preliminary mutagenicity study. In 1995, the FDA revised the import alert to allow the sale of stevia and its extracts as a food supplement, but not as a sweetener. It currently does not have GRAS status and is considered to be an unsafe food additive (Richard, 2002). 

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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Stevioside and rebaudioside A are diterpene glycosides. The sweetness is tainted with a bitter and undesirable aftertaste. The time—intensity profile is characteristic of naturally occurring sweeteners slow onset but lingering. The aglycone moiety, steviol [471 -80-7] (10), which is the principal metaboHte, has been reported to be mutagenic (79). Wide use of stevia ia Japan for over 20 years did not produce any known deleterious side effects. However, because no food additive petition has been presented to the FDA, stevioside and related materials caimot be used ia the United States. An import alert against stevia was issued by the FDA ia 1991. In 1995, however, the FDA revised this import alert to allow the importation and use of stevia as a diet supplement (80), but not as a sweetener or an ingredient for foods. Several comprehensive reviews of stevia are available (81,82). 

The binding specificity of d-[ C]glucose by the taste-papillae membranes, compared to that of control membranes isolated from epithelial tissue, has been confirmed in two studies. One inherent problem in the approach is that the stimuli, primarily carbohydrate sweeteners, are not ideal model compounds to use, as they are not active at low concentrations and do not show sufficiently high binding-constants. The use of other stimulus compounds that are at least several hundred times sweeter than sucrose, such as saccharin, dihydrochalcone sweeteners, dipeptide sweeteners, stevioside, perillartine and other sweet oximes, the 2-substituted 5-nitroanilines, and... 

Stevia, 12 42-43 Stevia plant, 24 239 Stevioside, 24 239-240 Stibabenzene, 3 72 Stibaboranes, 4 204 Stibiconite, 3 41 Stibine, 3 57-58 Stibine oxides, 3 73-74 Stibnite, 3 41 Stibonic acids, 3 72 Stichtite, 6 471t... 

Sweeteners can be roughly divided into two groups bulk and intense sweeteners. Prodolliet (1996) and Gloria (2000) reviewed thoroughly the analysis and properties of intense sweeteners acesulfame-K, alitame, cyclamate, aspartame, glycyrrhizin, neohesperidin DC, saccharin, stevioside, sucralose and thaumatin. They are generally used in low calorie products such as diet... 

SCIENTIFIC committee ON FOOD, Opinion on Stevioside as a sweetener, SCF/CS/ADD/EDUL/167, Bmssels, European Commission, 1999. 

Jeppesen PB, Gregersen S, Alstrup KK, Hermansen K. (2002) Stevioside induces antihyperglycaemic, insulinotropic and glucagonostatic effects in vivo Studies in the diabetic Goto-Kakizaki (GK) rats. Phytomedicine 9 9-14. 

Chen T-H, Chen S-C, Chan P, Chn Y-L, Yang H-Y, Cheng J-T. (2005) Mechanism of the hypoglycemic effect of stevioside, a glycoside of Stevia rebaudiana. Planta Me die a 71 108-113. 

Geeraert B, Crombe F, Hulsmans M, Benhabiles N, Geuns JM, Holvoet P. (2010) Stevioside inhibits atherosclerosis by improving insulin signaling and antioxidant defense in obese insulin resistant mice. Int J Obes 34 569-577. 

The plant Stevia rebaudiana bertoni has been studied in depth because it was discovered that this plant is the source of six sweet-tasting diterpene glycosides. They are stevioside, rebaudiosides A, C, D, E and dulcoside A. (Table 1). These sweet diterpene glycosides, as well as a complex mixture of organic compounds of which more than a hundred compounds have been identified, are found mainly in the leaves of the plant. The leaves contain a complex mixture of labdane diterpenes, triterpenes, stigmasterol, tannins and volatile oils. There is an abundance of reviews and patents relating to these sweet diterpene glycosides. 

Stevioside is the most abundant sweet-tasting compound in the leaves. Bridel and Lavielle isolated the crystalline glycoside, stevioside from an alcoholic extract of S. rebaudiana and found it to be 300 times sweeter than... 

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. 

Saponification of stevioside with a strong alkaline base yielded steviol-bioside. Although steviolbioside has been identified in some S. rebaudiana extracts, it is generally thought to be an artifact of extraction or isolation procedures rather than a naturally occurring glycoside. ... 

There are many patents and journal articles that describe processes to produce the principal sweet diterpene glycosides stevioside and in particular, rebaudioside A. Many of the reported methods of production require the use of ion exchange columns or gases and are not satisfactory if the scale-up to commercial quantities are required. Most methods for extraction and purification of the sweet diterpene glycosides from Stevia use complicated processing of the crude extracts. Generally, the recovery processes of the principal two diterpene glycosides stevioside and rebaudioside A involve ... 

Most sweet compounds including the commercial sweeteners, are small molecular weight compounds but there are also sweet macromolecules both synthetic and natural. It was thought that compounds with molecular masses over 2 500 would generally be tasteless. It was assumed that macromolecules such as proteins could elicit a sweet taste similar to small molecules such as sucrose and stevioside until the discovery of miraculin. 

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

The leaves of Stevia rebaudiana (Compositae) are a source of several sweet glycosides of steviol (26) (Fig. 15) [1, 61]. The major glycoside, stevioside (27), is used in oriental countries as a food sweetener and the second major glycoside named rebaudioside (28), which is sweeter and more delicious than stevioside, is utilized in beverages. 

Table 1 Relative sweetness intensity of various glucosyl derivatives 26-29 of stevioside [62]...

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