Formose sugars

Decker, R, Schweer, H., and Pohlmann, R. (1982). Identiflcation of formose sugars, presumable prebiotic metabolites, using capillary gas chromatography/gas chromatography-mass spectrometry of n-butoxime trifluoroacetates on OV-225. J. Chromatogr, 225, 281-91. 

Formose is a general term applied to the mixture of monosaccharides formed by self-addition of formaldehyde in aqueous alkaline solution. The present article briefly describes the history of research on formose, and discusses the formose reaction and the nature of the formose sugars. 

The main reactions for formose-sugar formation are the primary addition and then a secondary, crossed-aldol reaction. The former is the... 

Scheme 5.—A Model for the Synthetic Pathway of Formose Sugars."...

The conversion of formaldehyde by the Cannizzaro reaction into formic acid and methanol lessens the yield of formose sugars. Addition of... 

Formose sugars once formed are decomposed at extreme conversions, owing to the alkalinity of the reaction mixture (see Table IV, p. 188). The rate of decomposition depends on the kind of base used, its concentration, the reaction temperature, and the reaction period. A variety of compounds, such as acetals, acids, aldehydes, ketones, lactones, and saccharinic acids, are formed by decomposition. Such decomposition can be decreased by neutralizing the alkalis, or even by slightly acidifying the solution when the formose reaction reaches its peak rate, that is, soon after the solution in a batch reactor begins to turn yellow ( yellowing point ). 

The chromatograms in Fig. 15 also show the complex product-distribution of the per(trimethylsilyl) derivatives of the formose sugars at complete conversion. Greatly simplified chromatograms result by reduction of the formose sugars to the corresponding alditols. Branched-chain alditols are resolved from the normal-chain components as their per(trimethylsilyl) derivatives. Better resolution of the normal-chain species is accomplished by using the trifluoroacetates of the polyhydric alcohols. However, there is incomplete separation of the trifiuoroacetates of the branched-chain from those of the normal-chain alditols. 

Mizuno and coworkers tested the nutritive eflBcacy of formose by feeding young and adult rats with a purified mixture of the formose sugars. As shown in Figs. 20 and 21, the replacement of all, or half, of the natural sugar by formose caused profuse diarrhea, ending in the death of all of the rats. On autopsy, blisters in the intestine, the blind gut, and the colon were observed, as well as contracted spleen and liver and swollen kidneys and suprarenal bodies. When the replacement was... 

Fig. 22.—Utilization of Formose Sugars by Mold. RhiMpus sp., — Aspergillus sojae, —— .]...

Fig. 23.—Liquid-solid Chromatogram of Formose Sugars. [Apparatus Hitachi Type 034-0004-KLA-3B Liquid Chromatograph. Column 1.5 diam. X 50 cm, column temp. 55°. Packing Bio-Rad Resin Type AG 1 X2. Sample formose 19.65 mg/ 0.5 ml. Eluant 1, 0.25 M H.BO, pH 8.2, 385 min 2, 0.60 M H.BO., pH 10.2. Effluent flow-rate 15 ml/hr (6.0 kg/cm ) reagent flow-rate 45 ml/hr (5.9 kg/cm ). Reagent phosphoric acid + acetic acid + aniline. Reaction bath-temp. 120°. Reaction coil 0.8 diam. X 23 cm. Cell path 2 mm, wave length 365 nm. Chart speed 6 cm/hr. Scale 0-0.2 expansion. ]...

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