FEEDING EXPERIMENTS OF PYRIDOXINE DERIVATIVES AS VITAMIN-B-6

In order to compare the nutritional effect of vitamin B-6 derivatives, long-term feeding experiments with rats were carried out using pyrido xine-alpha-D-glucoside (PN-alpha-Glc), pyridoxine-beta-D-glucoside (PN -beta-Glc) or epsilon- (N-phosphopyridoxyl)lysine (PNP-Lys) with test diets consisting of basically the AIN-76 composition, except for the a ddition of 0.1 mg pyridoxine equivalent (PN eq.)/100 g diet. During 21 days of pair-feeding against the vitamin B-6-deficient diet group, bo dy weight gain, urinary excretion of xanthurenic acid and pyridoxic ac id were measured. After the feeding experiment, rats were killed and e xamined in terms of liver kynureninase activity (EC 3.7.1.3) with and without adding exogenous pyridoxal 5'-phosphate (PLP), erythrocyte asp artate aminotransferase activity (EC 2.6.1.1), as well as PLP concentr ation in blood. Rats fed with PN-alpha-Glc grew well, relative to the PN group. On the contrary, PN-beta-Glc poorly served as vitamin B-6 so urce, because average bioavailability was only about 22% in comparison to that of PN (100%). From this long-term feeding experiment, we have shown that PN-alpha-Glc (average bioavailability about 84%) is a good source of vitamin B-6 similar to PN.