Analysis Of Antioxidant Capacity Of Vegetables And Protection Against Oxidative Stress Induced By Swimming In Rats

ObjectiveTo determine the antioxidant capacity and contents of main antioxidants of 25 vegetables commonly consumed, investigate the effects of different cooking methods, compare the protective action of their juices against oxidative stress induced by swimming in rats, and study the related mechanisms by metabonomics.Methods1. The antioxidant capacity of vegetables was measured by FRAP assay and the contents of VC, total flavonoids and polyphenols by colorimetry.2. Effect of different cooking methods on antioxidant capacity and contents of related antioxidants was studied.3. The dynamic changes of serum antioxidant capacity were determined once or 7 days after intragastric administration of different vegetable juices in rats.4. The changes of antioxidant function after 4 weeks of intragastric administration of different vegetable juices were studied in rats under oxidative stress induced by swimming.5. A metabonomic approach was used by nuclear magnetic resonance analysis to investigate the related mechanisms of antioxidant action of different vegetable.Results1. Lotus root was the strongest in antioxidant capacity among all vegetables and followed by ginger, rape, garlic bulb, while celery, cucumber and pumpkin were the weakest. The antioxidant capacity of vegetables was significantly correlated to the contents of total polyphenols or flavonoids, but not to the content of VC.2. The antioxidant capacity and contents of related antioxidants of vegetables were preserved differently by various cooking methods, among which, stewing and microwaving were better.3. The serum antioxidant capacity of rats was neither increased obviously once or 7 days after gavage of the juices prepared from lotus roots with higher antioxidants, nor from cucumber with lower antioxidants.4. The serum antioxidant capacity was not significantly changed after 4 weeks of administration of three vegetable juices in rat. However, LS could lower MDA content in serum, liver, spleen and muscle and increase the antioxidant capacity of kidney significantly. RS could lower MDA content in liver and muscle significantly and raise the antioxidant capacity of muscle significantly. CS could lower MDA content in liver, kidney and muscle significantly. The antioxidant capacity of brain, heart and spleen was not significantly affected by all three vegetable juices.5. The antioxidant function was improved in swimming rats after administration of three vegetable juices for 4 weeks, as shown by decrease of MDA content, and increase of lowered VC, GSH contents , antioxidant capacity, and SOD, CAT and GSH-Px activities in serum. Likewise, the antioxidant capacity of heart, liver and muscle was increased, and MDA content lowered. The gastrocnemius mitochonrial function was protected significantly.6. The effects of different vegetable juices on serum metabonome were different. The energy metabolism was changed significantly after administration of vegetable juices, as indicated by increased contents of lactate,β- hydroxybutyrate, acetoacetate, choline, proline, threonine, lysine and decreased contents of arginine, aspartic acid.ConclusionThere were significant differences in antioxidant capacity and contents of polyphenols and flavonoids in the vegetables tested. Different cooking methods affected the antioxidant capacity and contents of related antioxidants differently. Administration of vegetable juices with different antioxidant capacity presented no significant effect on serum antioxidant capacity in normal rats, but protected significantly against the oxidative stress induced by swimming. The mechanism might be associated with the change of energy metabolism by metabonomic study.