ß-Nicotinamide Mononucleotide, an Anti-Aging Candidate Compound, Is Retained in the Body for Longer than Nicotinamide in Rats.

The turnover of the oxidized form of nicotinamide adenine dinucleotide (NAD+) has attracted interest in regard to longevity. Thus, compounds that can rapidly increase the cellular NAD+ concentration have been surveyed by many researchers. Of those, ß-nicotinamide mononucleotide (ß-NMN) has been focused on. Studies on the biosynthesis of NAD+ from ß-NMN have been reported at the cellular level, but not at the whole animal level. In the present study, we investigated whether ß-NMN is superior to nicotinamide (Nam) as a precursor of NAD+ in whole animal experiments. To this end we compared the NAD+ concentration in the blood and the urinary excretion amounts of NAD+ catabolites. Rats were intraperitoneally injected with ß-NMN or Nam. After the injection, blood samples and urine samples were collected at 3-h intervals. The concentration of blood total NAD (NAD11NADH) in each sample showed no significant differences between the two groups. The urinary excretion amounts of NAD+ catabolites in the urine samples collected at 3-6 h after the injection were lower in the ß-NMN group than in the Nam group. These results suggest that ß-NMN is retained in the body for longer than Nam.

Effects of Fatty Liver Induced by Excess Orotic Acid on B-Group Vitamin Concentrations of Liver, Blood, and Urine in Rats.

Fatty liver is caused when rats are given orotic acid of the pyrimidine base in large quantities. The lack of B-group vitamins suppresses the biosynthesis of fatty acids. We investigated how orotic acid-induced fatty liver affects the concentrations of liver, blood, and urine B-group vitamins in rats. The vitamin B6 and B12 concentrations of liver, blood, and urine were not affected by orotic acid-induced fatty liver. Vitamin B2 was measured only in the urine, but was unchanged. The liver, blood, and urine concentrations of niacin and its metabolites fell dramatically. Niacin and its metabolites in the liver, blood, and urine were affected as expected. Although the concentrations of vitamin B1, pantothenic acid, folate, and biotin in liver and blood were decreased by orotic acid-induced fatty liver, these urinary excretion amounts showed a specific pattern toward increase. Generally, as for the typical urinary excretion of B-group vitamins, these are excreted when the body is saturated. However, the ability to sustain vitamin B1, pantothenic acid, folate, and biotin decreased in fatty liver, which is hypothesized as a specific phenomenon. This metabolic response might occur to prevent an abnormally increased biosynthesis of fatty acids by orotic acid.

Conversion Percentage of Tryptophan to Nicotinamide is Higher in Rice Protein Diet than in Wheat Protein Diet in Rats.

We reported previously that the pellagragenic property of corn protein is not only low l-tryptophan concentration but also the lower conversion percentage of l-tryptophan to nicotinamide; the amino acid composition greatly affected the conversion percentage. The amino acid value of wheat protein is lower than that of rice protein. In the present study, we compare the conversion percentages of l-tryptophan to nicotinamide between wheat protein and rice protein diets in growing rats. The body weight gain for 28 days in rats fed with a 10% amino acid mixture diet with wheat protein was lower than that of rats fed with a 10% amino acid diet with rice protein (68.1 ± 1.6 g vs 108.4 ± 1.9 g; P < 0.05). The conversion percentage of l-tryptophan to nicotinamide was also lower for the wheat protein diet compared with the rice protein diet (1.44 ± 0.036% vs 2.84 ± 0.19%; P < 0.05). The addition of limiting amino acids (l-isoleucine, l-lysine, l-tryptophan, l-methionine, l-threonine) to the wheat protein diet improved growth and the conversion percentage. In conclusion, our result supports the thinking that the composition of amino acids affects the conversion ratio of l-tryptophan to nicotinamide.

Large-scale identification of protein-protein interaction of Escherichia coli K-12.

Protein-protein interactions play key roles in protein function and the structural organization of a cell. A thorough description of these interactions should facilitate elucidation of cellular activities, targeted-drug design, and whole cell engineering. A large-scale comprehensive pull-down assay was performed using a His-tagged Escherichia coli ORF clone library. Of 4339 bait proteins tested, partners were found for 2667, including 779 of unknown function. Proteins copurifying with hexahistidine-tagged baits on a Ni2+-NTA column were identified by MALDI-TOF MS (matrix-assisted laser desorption ionization time of flight mass spectrometry). An extended analysis of these interacting networks by bioinformatics and experimentation should provide new insights and novel strategies for E. coli systems biology.