Vitamin B1 deficiency inhibits the increased conversion of tryptophan to nicotinamide in severe food-restricted rats

Abstract

The conversion of tryptophan (Trp) → nicotinamide (Nam) is an important pathway for supplying vitamin niacin. We reported the following two phenomena: (1) severe food restriction led to an increase in the Trp → Nam conversion compared with free-access control group; (2) the conversion of Trp → Nam is also increased by vitamin B1 deficiency compared with free-access control group. The present study was done to clarify whether or not a true reason about an increase in the Trp → Nam conversion is a vitamin B1 deficiency or severe food restriction. The present results showed that vitamin B1 deficiency suppressed the increased conversion of Trp → Nam induced by severe food restriction, probably by suppressing 3-hydroxyanthranilic acid 3,4-dioxygenase protein synthesis in liver.

Effects of Mild and Severe Vitamin B1 Deficiencies on the Meiotic Maturation of Mice Oocytes

“…Anorexia is often observed as a symptom of severe vitamin B 1 deficiency. 26,27 Also, in the present study, food intake was reduced by feeding a vitamin B 1 -free diet. A recent study showed that vitamin B 1 deficiency induces anorexia by inhibiting the phosphorylation of AMP kinase (AMPK) in the hypothalamus.…”

Niacin in the Central Nervous System: An Update of Biological Aspects and Clinical Applications

“…Several nutritional, hormonal and physio-pathological factors affect the efficiency of this anabolic pathway. Deficiencies of vitamin B 6 , riboflavin, iron and heme (all essential cofactors for specific enzymes), as well as of vitamin B 1 and Trp itself, slow the reaction rate [18,20]. Overall: (i) a protein-enriched diet (particularly, consumption of foods with high concentrations of leucine, such as maize or sorghum) decreases niacin biosynthesis; (ii) unsaturated fatty acid-enriched diet increases it, while saturated fatty acids do not exert any effect; (iii) the transformation ratio is higher in diets containing starch with respect to sucrose-rich diets; (iv) caloric restriction drastically suppresses biosynthesis [18,21,22,23,24,25,26].…”

The chemistry of the vitamin B3 metabolome

“…While cofactors derived from riboflavin (vitamin B2) [97] and pyridoxine (vitamin B6) [98] are required by enzymes of the kynurenic pathway to generate quinolinic acid from tryptophan, NADP + and thiamine (vitamin B1) diphosphate are cofactors required for the synthesis of PRPP from glucose 6-phosphate [36]. This highlights the dependency of the NAD(P)(H) biosynthetic pathways on the bioavailability of three other metabolic cofactors, all derived from water soluble B-vitamins.…”

“…Vitamin B3 anabolites-Niacin (NA) and niacinamide (Nam) fall under the vitamin B3 denomination [1]. Intracellularly, NAD + is generated from dietary vitamin B3 or trp ( Figure 1) with the contribution made by the latter, known as the kynurenine pathway, varying greatly between species and organs [31][32][33][34][35][36]. Via the kynurenine pathway, biosynthetic precursors to NAD + include kynurenine, 3-hydroxykinurenine, 3-hydroxyanthranilate and quinolinate, leading to nicotinic acid mononucleotide (NAMN) [37].…”