天門冬胺酸及麩胺酸的羥?胺酸衍生物其生理活性功能之探討-----抗氧化、抑制血管收縮素轉換酵素和Semicarbazide - Sensitive Amine Oxidase

Monohydroxamates of Aspartic Acid and Glutamic Acid Exhibit Antioxidant and Inhibitory Activities against Angiotensin Converting Enzyme and Semicarbazide - Sensitive Amine Oxidase

林音秀(Yin-Shiou Lin)

指導教授 ： 侯文琪

臺北醫學大學/藥學院/生藥學研究所/碩士(2005年)

摘要

本研究以天門冬胺酸及麩胺酸的羥?胺酸衍生物為材料來探討其抗氧化、抑制血管收縮素轉化?（Angiotensin I Converting Enzyme）及抑制Semicarbazide- Sensitive Amine Oxidase之詳情。 抗氧化的結果發現，天門冬胺酸及麩胺酸的羥?胺酸衍生物具有清除DPPH自由基能力。IC50分別為36 μM及48 μM；清除超氧自由基方面，以化學法產生超氧自由基其IC50分別為18.99 mM及6.33 mM，而以酵素法產生超氧自由基其IC50分別為15.3 mM及7.25 mM；清除氫氧自由基能力IC50分別為0.66 mM及1.21 mM；兩者皆可抑制Peroxynitrite造成dihydrorhodamine 123氧化，DNA保護作用及抗低密度脂蛋白氧化。而對照組的天門冬醯胺酸及麩醯胺酸並不具上述之抗氧化的活性。 抑制血管收縮素轉化?的結果發現，天門冬胺酸及麩胺酸的羥?胺酸衍生物具有抑制血管收縮素轉化?活性，IC50分別為4.92 mM及6.56 mM（20 mU ACE）。而天門冬胺酸羥?胺酸對於基質FAPGG的抑制型態為競爭型抑制，Ki為2.20 mM。自發性高血壓鼠餵食實驗發現，一天餵食一次天門冬胺酸羥?胺酸（2 mg/kg B.W及5 mg/kg B.W）在第6小時有最高之降血壓量，收縮壓分別降37.8 mmHg及30 mmHg，舒張壓分別降42.19 mmHg及35.71 mmHg。而正對照組Captopril（2 mg/kg B.W）收縮壓及舒張壓分別降21.7 mmHg及32.14 mmHg。 抑制Semicarbazide- Sensitive Amine Oxidase的結果發現天門冬胺酸及麩胺酸的羥?胺酸衍生物具有抑制牛血漿中Semicarbazide- Sensitive Amine Oxidase的活性，IC50分別為0.7 mM及0.023 mM。由Semicarbazide- Sensitive Amine Oxidase的活性染色結果也可以發現天門冬胺酸及麩胺酸的羥?胺酸衍生物隨濃度增加有抑制牛血漿中的Semicarbazide- Sensitive Amine Oxidas活性。

關鍵字

抗氧化 ； 血管收縮素轉換酵素

並列摘要

The antioxidant activities and inhibitory activities against angiotensin converting enzyme (ACE) and semicarbazide-sensitive amine oxidase of monohydroxamates of aspartic acid and glutamic acid (L-aspartic acid ?-hydroxamate, AAH; L-glutamic acid ?-hydroxamate, GAH) were investigated in this thesis.. From the results of DPPH scavenging activities, it was found that both AAH and GAH exhibited dose-dependent scavenging activities, and the IC50 was 36 ?M and 48 ?M, respectively. For superoxide radical scavenging activities by the NADH-PMS generating system, the IC50 was 18.99 mM and 6.33 mM, respectively; and by xanthine/xanthine oxidase generating system, the IC50 was 15.3 mM and 7.25 mM, respectively. For hydroxyl radical scavenging activities by the Fenton reaction and detected by electron spin resonance (ESR), the IC50 was 0.66 mM and 1.21 mM, respectively. Both AAH and GAH exhibited dose-dependent antioxidant activities against peroxynitrite-mediated dihydrorhodamine 123 oxidation, and protection roles against calf thymus DNA oxidation and Cu2+-mediated LDL oxidation. However, both asparagines and glutamine were not found to have above-mentioned antioxidant activities. For ACE inhibitory activity, it was found that both AAH and GAH exhibited dose-dependent ACE inhibitory activities in vitro, and the IC50 was 4.92 mM and 6.56 mM, respectively (against 20 mU ACE). From the results of kinetic analysis, it was found that the AAH exhibited competitive inhibition against FAPGG, and the Ki was 2.20 mM. For antihypertension experiment in vivo, the spontaneously hypertensive rats (SHR) were used to measure the blood pressure (24 hs) after one oral administration of AAH (2 mg/kg B.W and 5 mg/kg B.W). It was found that the lowest blood pressure was reached at the 6th hour after one oral administration. For systolic blood pressure (SBP), there were 37.8 mmHg and 30 mmHg reductions, respectively; for 2 mg AAH/kg B.W. and 5 mg AAH/kg B.W. For diastolic blood pressure (DBP), there were 42.19 mmHg and 35.71 mmHg reductions, respectively, for 2 mg AAH/kg B.W and 5 mg AAH/kg B.W. The positive control values of captopril (2 mg/kg B.W), there were 21.7 mmHg and 32.14 mmHg reductions, respectively, for SBP and DBP. For SSAO (from bovine plasma) inhibitory activities, it was found that both AAH and GAH exhibited dose-dependent SSAO inhibitory activities, and the IC50 was 0.7 mM and 0.023 mM, respectively. The SSAO inhibitory activity was confirmed by SSAO activity stains.

並列關鍵字

Semicarbazide - Sensitive Amine Oxidase ； L-Glutamic acid γ-Monhydroxamate ； L-Aspartic acid β-hydroxamate

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