Abstract
The information on B_6 conjugates in plants are summarized as follows. 1. A main component of B_6 in most plant foods is glycosylated B_6. In addition, a new type of B_6 conjugate releasing free B_6 when treated with alkali and then β-glucosidase was present in brans and legumes. Three new pyridoxine (PN) glycosides were isolated from rice bran and identified. 2. The hydroxyl radical generated during autoxidation of ascorbic acid was proposed to be responsible for a loss of B_6 activity during storage, processing and cooking of plant foods. 3. The main metabolite of PN in plant seedlings was 5'-O-(β-D-glucopyranosyl) pyridoxine (PNG), and minor ones in seedlings of podded pea, Pisum sativum L. cv. Kinusaya, were 5'-O-[6-O-(3-hydroxy-3-methyl-4-carboxybutanoyl)-β-D-glucopyranosyl] pyridoxine and 5'-O-(6-O-malonyl-β-D-glucopyranosyl) pyridoxine. A UDP-glucosyltransferase catalyzing formation of PNG seemed to be widely distributed in plants. Properties of the particulate enzyme isolated from seedlings of podded pea were examined.
