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

为了评价类黄酮类化合物的化学预防作用，研究了类黄酮类化合物对人和小鼠循环系统的吸收以及对氧化应激的保护作用。这些类黄酮类化合物产生的活性氧产生氧自由基，并诱导脂质过氧化。采用Capcell Pak C18-UG 120色谱柱，用高效液相色谱法测定食物样品和血浆中8种黄酮类化合物(芦丁、杨梅苷、槲皮素、杨梅素、鱼腥草素、山奈酚、木犀草素、Eriodityol)的含量。来自七种膳食的冷冻干燥食品样本中含有从5毫克到30毫克的类黄酮。人血浆中含有60.8 mg的槲皮素和11.4 mg的山奈酚，在30-60min达到最高水平(<100 ng/ml)。在5h内，槲皮素浓度恢复到餐前水平。灌胃给药后30min，小鼠血浆中αG-芦丁浓度达到最高水平，60min内恢复至对照组水平。经1.5Gy射线照射前30min单次灌胃给予α-芦丁或木犀草素后，小鼠微核网织红细胞(MNRETs)发生率明显降低。经胃插管给予α-G-芦丁或木犀草素可抑制伽玛射线照射、Fe-NTA或阿霉素处理的小鼠骨髓、脾、肾和心脏的脂质过氧化。此外，α-G-芦丁对亚急性肾毒性有保护作用，诱导小鼠肾近端小管有核巨细胞。这些结果表明，吸收的类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化学预防与自由基相关的疾病，如癌症。

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.