Quercitrin functions as an antioxidant and protects UV-induced carcinogenesis

描述(申请人提供)：活性氧物种(ROS)和相关的氧化应激与多种疾病有关，包括心血管疾病、癌症、慢性肺部疾病和糖尿病。有利于清除ROS以减轻氧化应激的干预措施可能会预防氧化应激相关疾病。最近的研究表明，各种水果和蔬菜都含有高浓度的抗氧化剂。槲皮苷是一种糖基化形式的类黄酮类化合物，广泛存在于自然界，广泛存在于植物、水果、种子和蔬菜中。我们的初步研究表明，在相同的浓度范围内，该化合物表现出比抗坏血酸更强的抗氧化活性。阻断TPA诱导的JB6P+细胞恶性转化。槲皮苷可下调UVB或TPA诱导的JB6细胞AP-1、NF-：B的活化。在AP-1-荧光素酶转基因小鼠的皮肤上，局部应用槲皮苷显著阻断了TPA诱导的AP-1的激活。进一步的研究表明，这些抑制作用似乎是通过抑制MAPKs的磷酸化而实现的，其中包括ERKs、p38和JNKs。此外，槲皮苷还能刺激核因子-E2相关因子(Nrf2)的激活和GST-Are-荧光素酶的活性。彗星实验表明，槲皮苷能拮抗UVB诱导的DNA损伤。这些初步研究表明，栎皮苷可能是一种潜在的化学预防和化疗药物。这一应用的总体假设是，栎皮苷具有抗氧化剂的功能，并防止紫外线诱导的致癌作用。这项提议的目标是检验这一假设。目的1研究槲皮苷在非细胞和细胞内的抗氧化作用。我们将研究栎皮苷是清除还是抑制自由基的产生，并测定栎皮苷与氧自由基反应的反应速率常数。此外，我们还将利用在体电子自旋共振(ESR)自旋捕捉技术检测紫外线照射下活体动物皮肤产生的自由基，并对产生的自由基进行鉴定。目的2研究槲皮苷对紫外线诱导的无毛小鼠脂质、蛋白质和DNA的氧化损伤以及紫外线诱导的肿瘤形成和细胞增殖的抑制作用。这项研究代表了首次检测到由紫外线照射的活动物皮肤产生的自由基，并可能开辟一条新的途径来评估抗氧化剂对活动物产生的自由基的性能。这项研究的另一个重要意义是确定Qucertrin是一种预防紫外线诱发皮肤癌的药物。 公共卫生相关性：活性氧物种(ROS)和相关的氧化应激与各种疾病有关，包括心血管疾病、癌症、慢性肺部疾病和糖尿病。有利于清除ROS以减轻氧化应激的干预措施可能会预防氧化应激相关疾病。这项提议将检验一种假说，即在黑莓和其他食物中发现的一种化合物--栎皮苷，具有抗氧化剂的功能，并防止紫外线诱导的致癌作用。

DESCRIPTION (provided by applicant): Reactive oxygen species (ROS) and related oxidative stress are linked with various diseases including cardiovascular disease, cancer, chronic lung diseases, and diabetes mellitus. Interventions favoring the scavenging of ROS to attenuate the oxidative stress may prevent oxidant stress associated diseases. Recent studies suggest that various fruits and vegetables contain high concentrations of antioxidants. Quercitrin is a glycosylated form of flavonoid compounds, widely distributed in nature, and is ubiquitous in plants, fruits, seeds, and vegetables. Our preliminary studies show that this compound displayed a stronger antioxidant activity than that of ascorbic acid over the same concentration range. It blocked TPA-induced neoplastic transformation in JB6 P+ cells. Pretreatment of JB6 cells with quercitrin down-regulated activation of AP-1, NF- :B induced by UVB or TPA. In the skin of AP-1-luciferase transgenic mice, topical treatment of mouse with quercitrin markedly blocked the TPA-induced AP-1 activation. Further studies indicated that these inhibitory actions appear to be mediated through the inhibition of MAPKs phosphorylation, including ERKs, p38 kinase, and JNKs. In addition, quercitrin stimulated the activation of NF-E2-related factor (Nrf2) and GST ARE- luciferase activity. Comet assays showed that quercitrin could block DNA damage induced by UVB. These preliminary studies indicate that quercitrin may function as a potential chemopreventive and chemotherapeutic agent. The overall hypothesis of this application is that quercitrin functions as an antioxidant and protects UV- induced carcinogenesis. The goal of this proposal is to test this hypothesis. Aim 1 will investigate the antioxidant properties of quercitrin in both non-cellular and cellular. We will study whether quercitrin scavenges free radicals or inhibits their generation and determine reaction rate constants of the reactions between quercitrin and oxygen radicals. Moreover, we will detect the UV-induced free radical generation from UV- irradiated skin of living animal using in vivo electron spin resonance (ESR) spin trapping and identify the radicals generated. Aim 2 will investigate the inhibitory effects of quercitrin against the UV-induced oxidative damage to lipid, protein, and DNA, and UV-induced tumorigenesis and cell proliferation in SKH-1 hairless mice. This study represents first detection of free radicals generated by UV-irradiated skin of living animals and may potentially open a new avenue to evaluate the properties of antioxidant against free radicals generated in living animals. Another significance of the study is the identification of qucertrin as a preventive agent against UV-induced skin cancers. PUBLIC HEALTH RELEVANCE: Reactive oxygen species (ROS) and related oxidative stress are linked with various diseases including cardiovascular disease, cancer, chronic lung diseases, and diabetes mellitus. Interventions favoring the scavenging of ROS to attenuate the oxidative stress may prevent oxidative stress associated diseases. This proposal will test the hypothesis that quercitrin, a compound found in blackberries and other foods, functions as an antioxidant and protects UV-induced carcinogenesis.