紅麴山藥之最適發酵生產與預防粥狀動脈硬化之體內評估

Study on the optimal culture condition of Monascus-fermented dioscorea and the in vivo evaluation of reducing the risk of atherosclerosis

洪璽凱(Hsi-Kai Hung)

指導教授 ： 潘子明

國立臺灣大學/生命科學院/微生物與生化學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.02352

摘要

本研究以山藥為基質進行固態及液態培養，培養過程中藉控制 pH 值、加水量與添加低濃度的乙醇來降低 Monascus 生產紅麴時 citrinin 的生成量，並期望提高 monacolin K 生成量。同時比較玻璃缸與麴盤對紅麴次級代謝物 citrinin、monacolin K 生成之影響，以及不同品系山藥、不同培養條件、固態或搖瓶液態培養下紅麴次級代謝物生成量的不同。結果顯示，使用淮山藥為基質，利用 Monascus purpureus NTU 568 菌株以麴盤進行固態培養時有較好的效果，其 monacolin K 可達到 25,566 mg/kg，citrinin 之生成量為 3,166 μg/kg。而培養溫度、外添加水量與乙醇濃度對於固態發酵之紅麴山藥中 monacolin K 與 citrinin 的生成均有顯著影響。應用反應曲面法 (Response surface methodology, RSM) 進行最適培養條件的探討，結果當固態發酵之加水量 200 mL、溫度 34℃、乙醇濃度 0.53% 時可生成 39,800 mg/kg 之 monacolin K，且 citrinin 之生成量為 3,350 μg/kg。
本研究進一步以最適發酵條件生產高 monacolin K 產量與抗氧化效果佳的紅麴山藥，探討降血脂與抑制動脈粥狀硬化的效果。以高膽固醇倉鼠作為試驗動物，評估對血液總膽固醇、高密度脂蛋白膽固醇與低密度脂蛋白膽固醇濃度，以及對血漿中總抗氧化力與抗氧化酵素活性之影響。結果顯示，於不同劑量之山藥發酵紅麴所餵食之動物組，其血液中總膽固醇及低密度脂蛋白膽固醇濃度均顯著下降，高密度脂蛋白膽固醇濃度則無顯著差異。而血漿中總抗氧化狀態之測定，過氧化氫酶與超氧歧化酶活性分析，其結果均優於正常飲食控制組，並且有顯著差異。顯示山藥發酵紅麴對於降血脂以及抗粥狀動脈硬化具有良好的效果，應用在人體抗粥狀動脈硬化頗具潛力。

關鍵字

山藥 ； 紅麴 ； 發酵 ； 降血脂 ； 粥狀動脈硬化 ； 反應曲面法

並列摘要

In this study, we used dioscorea as substrate to culture Monascus purpureus NTU 568 under solid and submerged condition. In addition, various dioscorea species, culture conditions (cultural temperature, pH value and extra ethanol) and culture apparatus (koji disk and glass jar) were selected to investigate the effect on monacolin K and citinin production. In the result, koji disk and Dioscorea batatas were chosen as the optimal culture apparatus and dioscorea species for high monacolin K production and low citrinin formation, respectively. In addition, cultural temperature, pH value and extra ethanol would significantly influence monacolin K and citrinin production of M. purpureus NTU 568 under solid dioscorea fermentation, so they were chosen as the factors of the response surface methodology (RSM) experiment in order to investigate the optimal culture conditions. From the result of statistical figure, we can gain the high monacolin K production at 39,800 mg/kg and low citrinin production at 3,350 μg/kg from red mold dioscorea when the culture conditions are as following: water added (200 mL), 37oC, and 0.53% ethanol.
This study also used jar fermentor to investigate the reason why dioscorea would stimulate monacolin K formation of Monascus species. In the result, the pH value of dioscorea powder media would retain at 3.0 during Monascus fermentation. When we used the acidic rice powder media (pH 3.0) as the substrate to fermentation, the monacolin K production would significantly increased. Therefore we suggested that the pH value of culture condition at 3.0 is one of the most important reasons why dioscorea stimulated monacolin K formation. Importantly, the dry cell weight would be increased when the pH value was adjusted at 3.0 as compared with other pH value. In the mechanism of dioscorea stimulating monacolin K formation, we can presume dioscorea controlled the pH value of culture condition near 3.0, which would further stimulate the growth of Monascus and monacolin K accumulation.
This study further uses the optimal Monascus fermented dioscorea with high monacolin K production to investigate the effect of hypolipidemic, anti-atherosclerosis and anti-oxidation in a hamster model of hyperlipidemia. In addition, plasma cholesterol, high density lipoprotein (HDL) and low density lipoprotein (LDL) would be the evaluative marker for hypolipidemic effect. As regards the evaluation of anti-atherosclerosis and anti-oxidation in vivo, this study will assay the improvement effect in total antioxidant status and the activity of anti-oxidative enzyme.
The results showed that the plasma level of total cholesterol and LDL were decreased significantly in the Monascus fermented dioscorea feeding group compared to the normal group. It also indicates that Monascus fermented dioscorea would perform a potent effect on reducing the risk of hypolipidemic via the increase of total antioxidant status (TAS), catalase and superoxide dismutase activity, and which are superior to the control significantly. Therefore, these results suggest that the antioxidant and antiatherogenic effects of Monascus fermented dioscorea can be useful in the prevention of the atherosclerotic formation.

並列關鍵字

Monascus ； monacolin K ； dioscorea ； hypolipidemic ； response surface methodology

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