Abstract
Fractionation of wheat germ and trefoil seed, by the procedure including chromatography on an ion-exchange column and on an activated alumina column, and high-voltage paper electrophoresis, produced with the yield of vitamin B6 ranging 10 to 20% faintly yellowish residues, which unanimously yielded vitamin B6 on hydrolysis. The results of acid hydrolysis together with chemical and gas chromatographic analyses have shown that it consists of an equimolar amount of pyridoxine and glucose; the glycosidic linkage involved is susceptible to β-glucosidase. These results together with other consideration allowed to deduce its structure as pyridoxine-β-glucoside, which has been previously identified as one of major bound forms of vitamin B6 in rice bran.
Nutritional availability of the bound vitamin B6 was investigated with the bound vitamin preparation from rice bran administered either by oral ingestion (equivalent to 30μg of pyridoxine per rat every day for 2 weeks) or by intravenous injection (equivalent to 60μg of pyridoxine per rat in two doses) to male albino rats fed ad libitum a vitamin B6-deficient diet. The livers and erythrocytes of the animals were assayed for vitamin B6-dependent enzymes, glutamate-oxaloacetate transaminase and cystathionase. When the bound vitamin was orally ingested, the two enzyme activities in both livers and erythrocytes increased to essentially same levels as attainable by the ingestion of pyridoxine hydrochloride. On contrary, when parenterally administered, it was less significantly effective as compared to pyridoxine hydrochlaride. Hence, pyridoxine-β-glucoside occurring in cereals as one of major bound forms of vitamin B6 appears as such not adequately available in vivo but to be rendered available in the intestine.
