In vivo antioxidant activity of flavonoids and their evaluation as food factor

为了评价黄酮类化合物的化学预防活性，我们在暴露于γ射线、三乙酸铁（Fe-NTA）和阿霉素的雄性小鼠中，研究了黄酮类化合物对人体和小鼠循环系统的吸收，以及对氧化应激的保护作用。采用Capcell Pak C18-UG 120色谱柱，对食品样品和血浆中8种黄酮类化合物（芦丁、杨梅素、槲皮素、杨梅素、非赛特素、山奈酚、木犀草素、碘周醇）的含量进行了HPLC分析。从7种食物中提取的冻干食品样品含有5毫克至30毫克的类黄酮。人血浆中槲皮素的浓度在进食后30-60min达到最高水平（小于100ng/ml），其中槲皮素含量为60.8mg，山奈酚含量为11.4mg。槲皮素浓度在5h内恢复到原粕水平。小鼠血浆α - g -芦丁浓度在给药后30min达到最高，60min内恢复到对照水平。在γ辐照（1.5Gy）前30min，小鼠单次胃插管给予α -芦丁或木犀草素，观察到微核网状细胞（mnret）频率显著降低。经胃插管给予α -芦丁或木犀草素可抑制γ辐照、Fe-NTA或阿霉素处理小鼠骨髓、脾脏、肾脏和心脏的脂质过氧化。此外，经Fe-NTA处理的小鼠肾近端小管中，α - g -芦丁显示出对亚急性肾毒性的保护作用。这些结果表明，吸收的黄酮类化合物在体内具有抗氧化作用。每天摄入类黄酮可能有助于自由基相关疾病如癌症的化学预防。

In order to evaluate chemopreventive activity of flavonoids, the absorption of flavonoids into the circulatory systems of humans and mice, and the protective effects on oxidative stress, were examined in male mice exposed to gamma-ray, ferric nitrilotriacetate (Fe-NTA) and doxorubicin, which generate active oxygen species and induce lipid peroxidation.HPLC analysis, using Capcell Pak C18-UG 120 column, was carried out to determine the concentrations of eight flavonoids (rutin, myricitrin, quercetin, myricetin, fisetin, kaempferol, luteolin, eriodictyol) in food samples and blood plasma. Lyophilized food samples from seven kinds of meals contained from 5 mg to 30 mg of flavonoids. The concentration of quercetin in human plasma reached the highest level (less than 100ng/ml) 30-60min after ingestion of the meal, which contained 60.8mg of quercetin and 11.4mg of kaempferol. The concentration of quercetin retured to the pro-meal level within 5h. The mouse plasma concentration of alphaG-Rutin reached the highest level 30 min after oral administration and then returned to the control level within 60 min.When mice received alphaG-Rutin or luteolin by single gastric intubation 30min before gamma irradiation (1.5Gy), a significant reduction in the frequency of micronucleated reticulocytes (MNRETs) was observed. Administration of alphaG-Rutin or luteolin by gastric intubation suppressed lipid peroxidation in the bone marrow, spleen, kidney and heart of gamma-irradiated, Fe-NTA or doxorubicin treated mice. Further, alphaG-Rutin showed a protective effect against subacute nephrotoxicity as revealed by the induction of karyomegalic cells in the renal proximal tubules of mice treated with Fe-NTA.These results suggest that absorbed flavonoids works as an antioxidant in vivo. Daily intake of flavonoids may contribute to the chemoprevention of free radical-associated diseases such as cancer.