In vivo Effect of 1‐Amino D‐Proline, an Anti‐pyridoxine Factor, on the Metabolism of Vitamin B6‐dependent Enzymes in Moderately Vitamin B6 Deficient Rats

Abstract

Pyridoxal 5′‐phosphate (PLP) serves as an important cofactor in numerous metabolic pathways, including the transsulfuration pathway which converts homocysteine (Hcy) to cysteine (Cys). While overt deficiency is rare, marginal deficiency is common, and may be exacerbated by anti‐pyridoxine factors in the food supply. To this end, a study was conducted to examine the in vivo effect of 1‐amino D‐proline (1ADP), an anti‐pyridoxine factor found in flaxseed, on indices of sulphur amino acid metabolism in moderately B6‐deficient rats. Male weaning rats (n=6/treatment) received a semi‐purified diet (AIN‐93G) containing either 7 (control; C) or 0.7 mg/Kg diet PN·HCl (moderately deficient; MD), each with one of 4 levels of 1ADP, viz. 0, 0.1,1 and 10 mg/Kg, diet for 5 weeks. For rats receiving the C diet, final body weight was not affected by 1ADP, however rats consuming the highest 1ADP levels in the MD group were significantly lighter (p<0.001). Plasma biomarkers are given in Table 1. The data provide evidence that the consumption of an anti‐pyridoxine factor linked to flaxseed does not pose challenges for subjects who are vitamin B6‐replete. However, this may not be the case for subjects with marginal B6 status, as supported by dose‐dependent reductions in plasma PLP and increases in plasma Hcy.Grant Funding Source: Natural Sciences and Engineering Research Council of Canada (NSERC).