D-(-)-Fructose → (2R,3R,4S,5S)-2,3,4,5-tetrahydroxyhexanal

Participants

Reaction Steps

The sugar standards, (1 mg each) rhamnose, fructose, galactose, glucose and the internal standard Phenyl-β-D-Glucoside (E. Merck, Darmstadt) and the sugars (1 mg each) obtained from the hydrolysis of crude and pure anthocyanins (1-3) were reacted separately with 30 mg/ml Hydroxylamine HCl in dry pyridine (2 ml). The resulting oximes were then reacted with 1.0 ml hexamethyldisilazane (HMDS) and 0.1 ml trifluoroacetic acid (TFA) to yield their silyl derivatives. The samples were then analyzed by GC using an autosampler. Sugars from anthocyanins 1, 2 and 3 were identified by comparing with the retention times of sugar standards. The retention times were 6.97, 9.83, 10.58, 10.90, 19.82 minutes, respectively, for rhamnose, fructose, galactose, glucose and Phenyl-β-D-Glucoside. The GC analysis of sugars yielded from the hydrolysis of anthocyanins showed that anthocyanin 1 contained a 2:1 ratio of glucose and rhamnose. Anthocyanin 2 showed a 1:1 ratio of glucose and rhamnose and anthocyanin 3 had only glucose. Similarly, the GC analysis of sugars from the crude anthocyanin powder indicated that it contained only rhamnose and glucose at a ratio of 2:4, respectively.

Provenance & Evidence