天然物對胰島素及一氧化氮活性之調控

Regulatory Activities of Natural Products on Insulin Secretion and Nitric Oxide Synthase.

林慧宜(Hui-Yi Lin)

指導教授 ： 楊玲玲 教授 ； 許重輝 主任

臺北醫學大學/藥學院/生藥學研究所/碩士(2000年)

摘要

糖尿病為一種全身性慢性疾病，特別是其長久以來所導致之合併症如皮膚病變、發炎反應及敗血症都會對糖尿病患者造成危害。因此本論文中主要以天然之19種coumarins及28種polysaccharides進行其對誘導胰島素分泌及抗發炎之生理活性為目標而分為第一部份是天然物誘導胰島素分泌及作用機轉探討，第二部份是天然物對一氧化氮活性調控及消炎相關作用機制研究。 第一部份有關誘導Insulin分泌之研究，應用RIA 定量分析法測定20種coumarins及28種polysaccharides對胰臟b細胞(HIT-T15 cells) 誘導Insulin分泌，結果發現Coumarins之Phellopterin具有明顯誘導胰島素釋放作用，其對胰島素分泌機制受EDTA, EGTA, Nifedipin作用而分別降低33%, 60% 及92% 。因此可推斷Phellopterin誘導胰島素分泌作用之機轉與Ca+2有關。第二部份以開發NSAID（Non Steroid Anti-Inflammatory Drug）消炎藥物為目標；首先選用RAW 264.7 macrophage cells 以LPS誘導NO與PGE2產生，並分別以Griess reaction及PGE2 kit測定NO及PGE2含量。 在20種 Coumarins成份中Glabra-lactone能有效抑制NO及PGE2生成，其IC50分別為3.85 mg/mL與35.58 mg/mL，且以MTT分析細胞毒性試驗時Glabra-lactone並無顯著之毒性產生。以LPS誘導iNOS enzyme活性後Glabra-lactone並無法以直接或間接方式抑制iNOS enzyme活性。進一步以western blot分析 Glabra-lactone具有抑制iNOS及COX-2蛋白表現之作用，因而具有抑制NO自由基大量產生及消炎之作用。

關鍵字

HIT-T15 細胞株 ； RAW 264.7 細胞株 ； 胰島素 ； 一氧化氮合成脢 ； 多醣體 ； 香豆素

並列摘要

Diabetes mellitus is a generalized chronic disease and the complication of diabetes mellitus including dermopathy, inflammation and sepsis occur frequently in patients. In this study, nineteen coumarins- related compounds and twenty-eight polysaccharides isolated from natural products were used to study their effects on insulin secretion and anti-inflammation in HIT-T15 and RAW 264.7 cells, respectively. In HIT-T15 cells, the effects of coumarins and polysaccharides extracts were studied on insulin release by radioimmuno assay (RIA). Among these courmarins, phellopterin obviously stimulated insulin secretion and the insulin secretion was decreased by 33%, 60% and 92% in EDTA, EGTA and Nifedipine added reaction. On the other experiment, glabra-lactone , a kind of courmarins showed the significant inhibitory activity on LPS-induced NO and PGE2 production in RAW 264.7 macrophage cells and the IC50 value is 3.85 mg/mL and 35.58 mg/mL, respectively. By MTT assay, glabra-lactone showed less cytotoxicity in RAW 264.7 cells. In the same experiment, glabra-lactone was unable to inhibit NOS enzyme activity by indirect or direct NOS enzyme activity assays. Western blot analysis of iNOS and COX-2 proteins, showed that glabra-lactone effectively inhibited the expression of the LPS-inducible iNOS and COX-2 genes. Therefore, glabra-lactone might be a promising natural product in the treatment of LPS-induced response and deserves further study.

並列關鍵字

HIT-T15 ； RAW 264.7 ； Insulin ； NOS ； Polysaccharides ； Coumarins

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