Quercitrin functions as an antioxidant and protects UV-induced carcinogenesis

描述（由申请人提供）：活性氧（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、慢性肺病和糖尿病。有利于清除ROS以减轻氧化应激的干预措施可以预防氧化应激相关疾病。最近的研究表明，各种水果和蔬菜含有高浓度的抗氧化剂。槲皮苷是黄酮类化合物的糖基化形式，广泛分布于自然界中，并且普遍存在于植物、水果、种子和蔬菜中。我们的初步研究表明，这种化合物显示出更强的抗氧化活性比抗坏血酸在相同的浓度范围内。它阻断TPA诱导的JB 6 P+细胞的肿瘤转化。槲皮苷预处理可下调UVB或TPA诱导的AP-1、NF-：B的活化。在AP-1-荧光素酶转基因小鼠的皮肤中，用槲皮苷局部处理小鼠显著阻断TPA诱导的AP-1活化。进一步的研究表明，这些抑制作用似乎是通过抑制MAPK磷酸化介导的，包括ERK，p38激酶和JNKs。此外，槲皮苷刺激NF-E2相关因子（Nrf 2）和GST ARE-荧光素酶活性的激活。彗星实验表明槲皮苷能阻断UVB诱导的DNA损伤。这些初步研究表明，槲皮苷可能作为一个潜在的化学预防和化疗剂。本申请的总体假设是槲皮苷作为抗氧化剂起作用并保护UV诱导的致癌作用。本提案的目的是检验这一假设。目的1研究槲皮苷在非细胞和细胞内的抗氧化活性。我们将研究槲皮苷是否清除自由基或抑制自由基的产生，并确定槲皮苷与氧自由基之间反应的反应速率常数。此外，我们将使用活体电子自旋共振（ESR）自旋捕集技术检测紫外线照射活体动物皮肤引起的自由基产生，并鉴定所产生的自由基。目的2研究槲皮苷对紫外线诱导的脂质、蛋白质和DNA氧化损伤以及紫外线诱导的SKH-1无毛小鼠肿瘤发生和细胞增殖的抑制作用。这项研究代表了第一次检测的自由基产生的紫外线照射皮肤的活动物，并可能打开一个新的途径来评估抗氧化剂的性能对自由基产生的活动物。这项研究的另一个重要意义是确定了quucertrin作为预防紫外线引起的皮肤癌的预防剂。 公共卫生相关性：活性氧（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、慢性肺病和糖尿病。有利于清除ROS以减轻氧化应激的干预措施可以预防氧化应激相关疾病。这项提案将检验一种假说，即在黑莓和其他食物中发现的化合物槲皮苷具有抗氧化剂的功能，并保护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.