| Antioxidant has become a hot topic in people’s daily life and utilized in many fields, such as food, drugs, health products and cosmetics et al. After the hypothesis of aging free radical was put forward, many researches associated with antioxidant increased popularly because of that the antioxidant could remove oxidative damage induced by free radical.Many components of traditional Chinese medicine have exhibited their antioxidant effects. Fifteen kinds of Chinese medicine extract were harvested according to deal with nematodes by ultraviolet radiation. Among them, thirteen kinds of Chinese medicine extract exhibited more or less resistance to radiation damage except the remaining two. Mint and Rabdosia rubescens revealed their excellent effect on prolonging the lifetime of Caenorhabditis elegans and more than20% of lifetime was achieved at the concentration of 10 mg/m L.In this study, mint was selected as the research object. Firstly, five concentration gradient of mint extract were used and the best concentration was 15 mg/m L.Furthermore, to explain why mint could prolong the life of the worms and resistant to radiation, the content of free radicals(ROS) of C.elegans was carried out. The results showed that the ROS content of C.elegans rose sharply after radiation, while the ROS content of mint treated C.elegans significantly reduced. Based on this, mint could reduce the radiation damage by scavenging free radicals.Superoxide dismutase(SOD) is the main enzyme that can removal the ROS and insulin signaling pathway plays a key role in the process of regulating the SODexpression. In order to explore how the free radicals are cleared by mint in the worms, the mutant strains were utilized to determine whether the mint could regulate oxidative stress reaction by insulin signaling pathways. The results showed that daf-2, age 1, daf-16, sir-2.1 mutant strains significantly prolonged the lifetime of worms after being treated with mint, which meant that the antioxidant capacity of mint did not depend on insulin signaling pathway or sir-2.1.The SOD expression in SOD: : GFP C.elegans was tested. The results showed that even reduced the expression of SOD instead of increasing it. Then the SOD activity of C.elegans was carried out and the activity of SOD enzyme was not improved. It was suspected that mint could clear the free radicals of worms body through its own antioxidant ability. Based on this, DPPH free radicals strategy was used to detect the antioxidant capacity of mint water extract. As was expected, the results showed that mint itself could remove free radicals and the effect was concentration dependent, which was consistent with the former life test.The quantitive expression of hcf-1 was measured by fluorescence quantitative PCR(q PCR) to verify the influence of mint and the results exhibited that mint could increase the expression of hcf-1. Although mint had strong ability to resist radiation and reduce oxidative damage induced by free radicals, the experiment results showed that the mint could play a complex role in C.elegans.In this study, the influence of mint to C. elegans radiation stress and its radiation resistance mechanism was carried out in-depth, which have instructive significance on some complicated problems, such as how to combat free radicals effectively and anti-aging, This study laid a solid foundation in the future study of the stress response of the organism and the development of human anti-radiation drugs. |
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