含 γ-胺基丁酸與血管收縮素 I 轉化酶抑制劑紅麴山藥之最適化生產與降血壓功效評估

Abstract

高血壓是造成代謝症候群的危險因子之一，須長期靠降壓物質控制。紅麴發酵產物含有降血壓功效物質 γ-胺基丁酸 (γ-aminobutyric acid, GABA)，為抑制性神經傳導物質，可引起血管的擴張。本研究建立了紅麴發酵產物酒萃物中 acid form 及 lactone form monacolin K、citrinin、黃色素 monascin 及 ankaflavin 的同步分析方法，以及水萃物 GABA 的衍生化分析方法，再以 Monascus purpureus NTU 568 固態發酵方式篩選出最適培養方式及基質，以厭氧處理時間、厭氧處理起始時間及乙醇添加量，藉由三因子三階層的反應曲面法提高 GABA 含量。結果顯示，以山藥為基質生產之 GABA 較米高，發酵過程 GABA 含量在第六天最高，在第八天開始厭氧處理 60 小時及 3% 乙醇添加下可使 GABA 含量從 134 mg/kg 提高至 513 mg/kg，citrinin 從 30.81 ppm 降低至 6.35 ppm，趨勢顯示厭氧可造成 GABA 含量提升及 citrinin 含量下降。蛋白質經蛋白酶水解或微生物發酵生成之短鏈胜肽，具有血管張力素轉換酶抑制劑 (angiotensin I converting enzyme inhibitor, ACEI) 的活性，ACEI 為一降血壓物質。本研究又利用固態發酵得到的紅麴米與紅麴山藥進行ACEI活性分析，再以自發性高血壓大鼠 (spontaneous hypertensive rat, SHR) 經過連續八週管餵紅麴米或紅麴山藥，以評估短效性與長效性降血壓效果。結果顯示，單一次餵食後紅麴米可降低收縮壓 8 mmHg 與舒張壓 9 mmHg，紅麴山藥顯著降低收縮壓 20 mmHg 與舒張壓 17 mmHg (p<0.05)，且持續至八小時後仍有效果；餵食八週後紅麴米顯著降低收縮壓 20 mmHg 與舒張壓 18 mmHg (p<0.05)，紅麴山藥顯著降低收縮壓 26 mmHg 與舒張壓 22 mmHg (p<0.05)，且不會造成肝、腎、肌肉、心律影響及體內電解質不平衡，紅麴山藥在動物試驗結果顯示較紅麴米有更顯著降血壓效果。

Hypertension is one critical factor of metabolic symdromes, and it has to be controlled by anti-hypertensive substances. Red mold fermented products contain an antihypertensive substance, γ-aminobutyric acid (GABA). GABA is one of the inhibitory neurotransmitters, and it can cause blood vessel relaxation. In this study, we established a rapid synchronous analysis method for detection of acid form and lactone form of monaolin K, citrinin, monascin, and ankaflavin levels in red mold fermented products ethanol extracts. And we also established an analysis method for the detection of GABA level in red mold fermented products aqueous extracts. In addition, various cultivation containers (tray and packed-bottle), substrate, culture conditions (pH, cultural time, ethanol addition and anaerobic treatment time) were selected to investigate the effect on GABA and citrinin production. In the result, tray and Dioscorea batatas were chosen as optimal culture apparatus and substrate, respectively. Furthermore, cultural time, ethanol addition and anaerobic treatment time significantly influenced both GABA and citrinin production of M. purpureus NTU 568 under solid state dioscorea fermentation, so they were chosen as the factors of the response surface methodology (RSM) experiment in order to investigate the optimal culture condition. From the result of statistical figures, we can gain the GABA production at 513 mg/kg and citrinin production at 6,350 μg/kg from red mold dioscorea when the culture conditions are as following: culture 8 days, anaerobic treatment 60 hours, and adding 3% ethanol. We further used the Monascus fermented dioscorea with high GABA production to investigate the effect on anti-hypertension in rat model of spontaneous hypertension. The result showed that the systolic and diastolic blood pressure levels were decreased significantly after eight-hour daily oral administration, but the heart rates were not affected. The systolic and diastolic blood pressure levels were decreased significantly after eighth-week long-term oral administration, but the heart rates were not affected. From the result of tissue section staining of the aorta elastin fiber, rats with orally administrated red mold dioscorea had elastin fiber more straight than the control group. Therefore, these results suggest that anti-hypertensive effect of Monascus fermented dioscorea can prevent hypertension effectively.