Verbascose

The predominant polysaccharide in dehulled field pea flour is starch (49.7-59.8%) and the major soluble sugars are a-galactosides (4.78%) and sucrose (1.85-2.2%) (8,23,24). Verbascose is the major a-galactoside present in field pea flour (23,24). The a-galactosides are the main contributors to the flatulence caused by ingestion of legume flours. 

Sagittardia sagittifolia L. Ci Gu (Arrow head) (whole plant) d-raffinose, d-stachyose, d-verbascose, d-fructose, d-galactose, glucose, asparagine, vitamin B.48 Bruised leaves for bugbite, foul sores, scrofulous ulcers, antilactogogue. 

Fig. 3 HPLC separation of carbohydrates in chickpeas. Column (200 X 4.6-mm ID) LiChrosorb NH2 flow rate 1 ml min-1 mobile phase 20% water in acetonitrile. Refractive index detector. Peak assignment 1, fructose 2, glucose 3, sucrose 4, rafflnose 5, maninotriose 6, stachyose 7, verbascose.

Kandler and coworkers818 isolated from the mature seeds of V.faba (see also, Refs. 293 and 298) an enzyme that transfers the D-galactosyl group of galactinol to raffinose, yielding stachyose (compare with Refs. 34, 296, and 615), and to stachyose, yielding verbascose. When... 

Molecular and partial structural formula for verbascose Discovery, crystallization, and molecular formula for Murakami 1940 21... 

Fig. 1.—Molecular-rotation relationships of several raffinose-type oligosaccharides. Me, methyl a-D-galactopy ranoside Gl, D-glucose Mb, melibiose Mt, manninotriose Vt, verbascotetraose S, D-glucitol M, melibiitol Ml, manninotriitol Su, sucrose K, raffinose St, stachyose V, verbascose Gb, gentiobiose Ge, gentianose.

In 1910, Bourquelot and Bridel reported17 the isolation of a new oligosaccharide, verbascose, from the roots of the mullein, Verbascum thapsus. 

In 1940, Murakami published a study21 of the constitution of verbascose. To prepare this sugar, Murakami extracted the finely ground roots with 95% alcohol, clarified the extract with lead acetate, and precipitated the verbascose with barium hydroxide and alcohol. After processing the barium complex in the usual way, and precipitating the saccharide several times from an aqueous solution by alcohol, Murakami obtained verbascose in 0.5-mm. spherocrystals composed of fine needles these had m.p. 253°, [a]20D + 170.2° (in water). The elementary analysis and the cryoscopic molecular-weight values were appropriate for a pentasaccharide. 

Methylation of verbascose, and hydrolysis, gave21 2,3,4,6-tetra-O-methyl-D-galactose (identified as the crystalline anilide), 2,3,4-tri-O-methyl-D-galactose (crystalline, identified by converting it into the 6-0-trityl derivative), 1,3,4,6-tetra-O-methyl-D-fructose (identified by analytical data and by its optical rotation), and a tri-O-methyl-D-glucose which, on further methylation, was converted into 2,3,4,6-tetra-O-methyl-D-glucose (identified through the crystalline anilide). 

To the present author, it seems more probable that the partially methylated D-gluconic acid obtained by Murakami was the 2,3,4,5-isomer, but it is obviously desirable to bring more experimental information into this area, so that the constitution of verbascose can be clarified. 

Recently, French33 has been able to prepare verbascotetraitol in crystalline form, by separation of the reduced oligosaccharides from ash manna. Likewise, the trisaccharide galactotriose, which is a component moiety in verbascose, has been obtained33 as a crystalline material. Although these compounds may eventually prove to be valuable reference compounds in the detailed examination of the verbascose structure, definitive, structural studies on these new compounds are as yet lacking. 

The formula given at the head of this Section for verbascose must, then, be regarded as a provisional fortnula, or suggestion, which has not been thoroughly developed. That the extension of the chemical and biochemical methods used so successfully with stachyose will prove to be of value in the study of verbascose, as well, may confidently be expected. 

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