Studies On The Antioxidant Ability Of Nucleotides And Their Effects On Antioxidant Genes Of Mice

Nucleotide was always considered as a kind of conditional basic nutrients. It produced important beneficial effects during several special times. However, it may be not only a conditional nutrient, but also a natural antioxidant. In this study, several advanced methods were used to study antioxidant effects of nucleotide, to reveal its possible mechanism of action. This will provide a basis for further develop of the use of nucleotide in scientific.In this paper, scavenging of hydroxyl free radical(·OH), DPPH free radical(DPPH·) and superoxide free radical(·O^2-) by nucleotides (5'-AMP, 5'-CMP, 5'-GMP, 5'-UMP) was studied by chemical colorimetry; flow injection chemiluminescence method also was used to evaluate the antioxidant capacity of the nucleotides in vitro. Under alkalescence condition, Superoxide free radical induced and enhanced Luminol chemiluminescence; MTT method was used to study repairing of H₂O₂ induced splenic and liver cells oxidative damage; In addition, mice (male, 11¹3g) were fed 0 or 0.25% nucleotides-supplemented diet respectively for 15 day. Mice were lavaged with physiological saline (control) or CpG DNA (experimental groups), and were killed 4h later. The possible mechanism was analyzed by using genechip.It was indicated that nucleotides could scavenge hydroxyl radical and DPPH radical in concentration dependent way in vitro and significantly repair the injury of splenic and liver cells induced by H₂O₂. The hydroxyl scavenging capacities of 5'-AMP and 5'-CMP were as high as 0.75 times of Vc. However, scavenging capacities of DPPH free radical were much weaker. It was showed that the four nucleotides can effectively inhibit the reaction of Luminol chemiluminescence. Further more, as the nucleotide concentration in the system increased, the luminescence intensity decreased. The experimental results showed that nucleotides have strong antioxidant properties.The number of live cells increased significantly in H₂O₂ injuried splenic and liver cells cultured in Vitro, with the supplementation of 0.5 mmol·L-1, 1 mmol·L-1, 5 mmol·L-1 and 10 mmol·L-1 nucleotides (P<0.01). CAT activities, GSH-Px activities and T-AOC in incubation medium were increased significantly with nucleotides concentration increased (P<0.01), while MDA content decreased significantly (P<0.01) with supplementation of more than 1 mmol·L-1 nucleotides to the injured group. ROS level decreased gradually, 10 mmol·L-1 of 5'-nucleotides obtained best effect, which is close to control group.The Affymetrix genechip results showed the genes concerned material metabolism and antioxidase were up-regulated under CpG DNA stimulation. But the genes concerned antioxidations were down-regulated and the genes concerned DNA repairs were up-regulated with nucleotides supplemented.It was concluded that nucleotides have the significant anti-oxidation activity. Nucleotides, possibly by scavenging of hydroxyl free radicals, and changing the level of free radical, protect mice from antioxidative injury.