Kashino Yasuaki, Murota Kaeko, Matsuda Namiko, Tomotake Muneaki, Hamano Takuya, Mukai Rie, Terao Junji
Dept. of Food Science, Inst. of Biomedical Sciences Tokushima Univ. Graduate School, Tokushima Univ, Tokushima, 770-8503, Japan.
Faculty of Science and Engineering, Dept. of Life Science, Kindai Univ, 3-4-1 Kowakae, Higashi-Osaka, 577-8502, Osaka, Japan.
J Food Sci. 2015 Nov;80(11):H2597-602. doi: 10.1111/1750-3841.13079. Epub 2015 Sep 16.
Onion is a major dietary source of the bioactive flavonoid, quercetin. Quercetin aglycone (QA) is exclusively distributed in the onion peel, although quercetin-4'-β-O-glucoside (Q4'G) is present in both the peel and the bulb, and quercetin-3,4'-β-O-diglucoside (Q3,4'diG) is present only the bulb. The bioavailability of flavonoids from fruits and vegetables is frequently affected by the manufacturing process and related conditions. The present study aimed to estimate the effect of food processing on the bioavailability of onion QA and its glucosides, Q4'G and Q3,4'diG, provided through the consumption of onion products. Rats were fed onion peel and onion bulb products-mixed meal or pure QA/Q4'G+Q3,4'diG-mixed meal at 5 mg QA equivalent/kg body weight. A comparison of the blood plasma concentrations strongly suggested that quercetin glucosides (Q4'G and Q3,4'diG) are superior or at least equal to QA in their bioavailability, when each purified compound is mixed with the meal. The intake of a peel powder-containing meal provided a significantly higher increase of plasma quercetin concentration than the peel extract, bulb powder, bulb extract, and bulb sauté containing meals at each period tested. A human ingestion study confirmed the superiority of onion peel powder to onion peel extract. The difference of log P for QA between peel powder and peel extract indicated that a food matrix improves the bioavailability of QA in onion peel products. These results demonstrated that the bioavailability of quercetin provided by not the onion bulb but the onion peel is significantly affected by food processing.
Onion is a popular source of antioxidative flavonoid quercetin and its vascular function attracts considerable attention in relation to anti-atherosclerotic effect. The present study estimated the effect of food processing on the bioavailability of onion quercetin aglycone and its glucosides provided through the consumption of onion products. The intake of a peel powder-containing meal showed a significantly higher bioavailability than the peel extract, bulb powder, bulb extract, and bulb sauté containing meals. Hence, food processing of onion peel may enhance the health impact of onion quercetin by elevating its bioavailability.
洋葱是生物活性黄酮类化合物槲皮素的主要膳食来源。槲皮素苷元（QA）仅分布在洋葱皮中，而槲皮素 - 4'-β - O - 葡萄糖苷（Q4'G）在皮和鳞茎中均有存在，槲皮素 - 3,4'-β - O - 二葡萄糖苷（Q3,4'diG）仅存在于鳞茎中。水果和蔬菜中黄酮类化合物的生物利用度常常受到加工过程及相关条件的影响。本研究旨在评估食品加工对通过食用洋葱制品所提供的洋葱QA及其糖苷Q4'G和Q3,4'diG生物利用度的影响。给大鼠喂食洋葱皮和洋葱鳞茎制品混合餐或纯QA/Q4'G + Q3,4'diG混合餐，剂量为5毫克QA当量/千克体重。血浆浓度比较强烈表明，当每种纯化化合物与餐混合时，槲皮素糖苷（Q4'G和Q3,4'diG）在生物利用度方面优于或至少等同于QA。在每个测试时间段，摄入含皮粉的餐比含皮提取物、鳞茎粉、鳞茎提取物和炒鳞茎的餐能使血浆槲皮素浓度显著更高地升高。一项人体摄入研究证实了洋葱皮粉优于洋葱皮提取物。皮粉和皮提取物中QA的log P差异表明食物基质提高了洋葱皮制品中QA的生物利用度。这些结果表明，提供槲皮素的不是洋葱鳞茎而是洋葱皮，其生物利用度受到食品加工的显著影响。
洋葱是抗氧化黄酮类化合物槲皮素的常见来源，其血管功能因其抗动脉粥样硬化作用而备受关注。本研究评估了食品加工对通过食用洋葱制品所提供的洋葱槲皮素苷元及其糖苷生物利用度的影响。摄入含皮粉的餐显示出比含皮提取物、鳞茎粉、鳞茎提取物和炒鳞茎的餐显著更高的生物利用度。因此，洋葱皮的食品加工可能通过提高其生物利用度来增强洋葱槲皮素对健康的影响。
