- 學位論文
紅甘藷葉對人體抗氧化、免疫調節及促血管新生活性之影響
Effects of Purple Sweet Potato Leaves on Antioxidant Activity, Immune Function and Serum Angiogenic Activity in human
摘要
本研究主要的目的是探討紅甘藷葉多酚類的生體可利用率，以及長期攝取紅甘藷葉，是否可以改善人體抗氧化、免疫功能及血管新生等生理作用。實驗共分三個部份，第一個部份，給予受試者200公克油炒之紅甘藷葉，並分別於0、0.5、1、2、3、6、12、24小時採集血液，以分析紅甘藷葉多酚類的生體可利用率。第二部分的實驗是採用隨機、交叉試驗的方式，共進行7週。包括1週的飲食調整期，及二階段的飲食補充期各2週，中間有2週的排空期。經過1週的飲食調整期，16位受試者隨機分成2組，一組攝取低多酚類飲食（LPD 組），一組每日額外攝取200公克的紅甘藷葉（PSPL組），持續進行2週，接下來進行2週的排空期，之後2組交換。分別抽取攝食前及攝食後1及2週的空腹血進行分析。第三部分則分別以體外及老鼠體內實驗之模式來探討紅甘藷葉對於血管新生作用的影響。第一部分結果顯示，攝取紅甘藷葉後，血漿中多酚類的濃度快速地上升，於 1小時到達血漿中最高濃度，其最高濃度為1.9±0.4 μmol/L。血漿中黃酮類化合物的濃度在攝取紅甘藷葉後2-3小時，出現血漿濃度的高峰值。第二部分的實驗中發現，連續攝取紅甘藷葉2週之後，明顯增加尿液中多酚類的濃度。在抗氧化的結果方面，PSPL組在攝取紅甘藷葉2週之後，血球中GSH濃度明顯增加33.3％，LDL-lag time亦有明顯延長的現象；在攝取紅甘藷葉1週及2週後，也降低DNA的受損指標8-OHdG的濃度，分別降低了36.7 and 17.4%，顯示攝取紅甘藷葉可以減少DNA的氧化損傷。在免疫功能方面，淋巴細胞增殖能力、細胞激素IL-2、IL-4分泌及自然殺手細胞的毒殺能力，在攝取紅甘藷葉後1及2週，均明顯大於控制組，與發炎有關的細胞激素TNF-α，在攝取紅甘藷葉後1及2週，則明顯降低。受試者攝取紅甘藷葉2週後，唾液中sIgA的濃度則明顯上升，顯示紅甘藷葉具有提高黏膜保護的作用。在血管新生作用方面，攝取紅甘藷葉2週後，沒有明顯增加HUVECs細胞增殖能力，但是明顯增加細胞移動能力及類血管形成，並且明顯增加MMP-9的表現，顯示具有促進血管形成的作用。在血管新生作用的體外實驗中發現，給予HUVECs細胞處理不同濃度的紅甘藷葉多酚類粗萃物，隨濃度增加明顯抑制血管新生作用，並且抑制VEGFR及MMP-2的表現。鼠體內血管新生的實驗結果顯示，攝取紅甘藷葉有輕微增加鼠體內血管新生的情形。 本研究結果顯示，紅甘藷葉之多酚類能快速被人體吸收，長期攝取紅甘藷葉可以改善人體抗氧化功能，降低氧化壓力，特別是減少DNA的氧化損傷；亦明顯增強人體對外來病菌的防禦能力，減少促進發炎介質TNF-α的分泌；同時比控制組明顯促進血管形成及MMP-9的表現。紅甘藷葉之多酚類萃取物，隨濃度增加明顯抑制血管新生作用，其抑制作用可能來自於減少VEGFR的表現及下降MMP-2的表現。
並列摘要
The aims of this present study was conducted three parts. First part was to investigate the bioavailability in human after consuming 200 g fried purple sweet potato leaves（PSPL）. The second part was to evaluate the effects of antioxidative status, immune function and angiogenesis after consuming 200g PSPL per day for 2 weeks. The third part was to investigate the effect of crude extract from PSPL on angiogenesis of human Umbilical Vein Endothelial Cells（HUVECs）. The results showed plasma levels of polyphenols was fast increased and a peak of 1 h after ingestion of PSPL. The highest concentration of polyphenols on plasma was 1.9±0.4 μmol/L. The plasma levels of flavonols reached a peak after comsunption PSPL for 2-3 h. After 2-wk of PSPL consumption could enhance urinary polyphenol excretion by 25.2％, but did not significantly alter plasma polyphenol level. Glutathione concentration in erythrocytes were significantly enhanced by 33.3％ in PSPL group, the urinary 8-hydroxy-deocyguanosine was significantly decreased 36.7％ after 1 wk-PSPL supplementation. The consumption of PSPL produced a significant increase in proliferation responsiveness of peripheral blood mononuclear cells（PBMCs）and their secretion of immunoreactive interleukin-2 and interleukin-4, but significantly decreased the secretion of TNF-α. As well, lytic activity in NK cells and salivary IgA secretion were elevated after consuming PSPL for 2 weeks. The migration ,formation of tubular structures and the protein expression of MMP-9 were significantly increased of HUVECs treated with 5％ serum from PSPL group. The study of in vitro angiogenesis showed PSPL crude extract could inhibit HUVECs cell proliferation and decreased tubule formation in a dose response. PSLE crude extract also significantly decreased metalloproteinase-2（MMP-2）and vascular endothelial growth factor receptor（VEGFR）protein expression. In vivo study showed mild increased angiogenesis after feeding PSPL. In conclusion, the polyphenols of PSPL was bioavailable and consuming PSPL for 2 weeks could enhance antioxidative status, immune function and angiogenesis. High concentration PSPL extract could inhibit VEGF-mediated angiogenesis.