紅麴菌株鑑定及其發酵產物對於改善糖尿病病情之研究

Abstract

利用本研究室分離出來的 Monascus purpureus NTU 568 發酵所得之紅麴發酵產物，具有多種保健功效，包括降血脂、抗疲勞、抑制類澱粉蛋白沉積、預防肥胖及抑制腫瘤細胞轉移。藉由形態觀察 (子囊孢子大小、培養基上生長菌落大小) 以及核醣體 RNA 基因 (ITS1、ITS2、5.8S、18S rRNA) 序列之分子生物學鑑定，鑑別本實驗室所分離之紅麴菌株 NTU 568 是否為 M. purpureus 之物種，並與其他相關菌株 (M. ruber、M. pilosus) 進行形態觀察及序列比對與鑑別。實驗結果顯示本實驗室所分離菌株 NTU 568 與食品工業發展研究所生物資源保存及研究中心之菌株 BCRC 31615- M. purpureus 就形態及基因序列極為相似，應屬同種之相似菌株。本研究以 NTU 568 菌株進行相關研究。 本研究乃以不同基質 (米、山藥及薏仁) 發酵之紅麴產物，提高代謝產物為目標，採用體內動物評估模式，探討紅麴發酵產物對改善糖尿病病情之作用機轉。本研究發現，餵食 8 週 M. purpureus NTU 568 紅麴發酵產物 (200 mg/kg bw) 對於 STZ 誘導之糖尿病動物具改善效果，其可降低 STZ 老鼠之空腹血糖並改善葡萄糖耐受能力，且可顯著降低尿液中葡萄糖與蛋白質含量及減少血液中膽固醇及三酸甘油酯濃度，顯示紅麴對糖尿病症狀具改善效應。許多研究發現氧化壓力與糖尿病有相關性，而餵食 8 週 M. purpureus NTU 568 紅麴發酵產物後，可降低活性氧生成，且可提升胰臟抗氧化酵素活性，包括 CAT、GR、GPx 及 SOD，這些結果顯示，紅麴發酵產物可預防氧化壓力對 STZ 老鼠之胰臟所造成的氧化性損傷，以達保護效應，且該預防效應以紅麴山藥效果為最佳。 糖尿病之併發症大多伴隨體內氧化壓力之上升及發炎因子之增加，氧化壓力與發炎反應對於組織產生胰島素抗性扮演重要角色，因山藥與紅麴皆富含抗氧化組成，故本研究進一步探討紅麴山藥改善 STZ 誘發氧化傷害及發炎現象之改善效應。結果發現，STZ 老鼠經餵食紅麴山藥 6 週後除可降低血糖、膽固醇及游離脂肪酸含量，也可有效抑制發炎因子 IL-6、IL-1β 及 TNF-α 生成。綜合以上結果可知，利用菌株 M. purpureus NTU 568發酵之產物除可調節血糖外，更可藉由提升抗氧化活性而對胰臟具保護效果，抑制發炎因子生成而減緩 STZ 對胰臟所造成之傷害，顯示紅麴可開發為預防糖尿病之天然保健食材。

Strain NTU 568 was a Monascus isolated from red mold rice by our laboratory. In our previous study, strain NTU 568 has several functions of reducing blood serum lipid, antifatigue, decreasing amyloid peptide accumulation, prevention of obesity and inhibiting lung cancer cell migration. The morphological observations, which include colonies size, ascospores size, and the partial sequences of ribosomal RNA genes- the internal transcribed spacer 1 (ITS1), 5.8S ribosomal RNA gene, internal transcribed spacer 2 (ITS2), and 18S ribosomal RNA gene, were applied to identify the strain NTU 568. Comparisons of partial nucleotide sequences and morphology with the strains from different genus (M. purpureus, M. ruber and M. pilosus) were made. The DNA sequences data demonstrated that strain NTU 568 was similar to BCRC 31615 (M. purpureus). The morphological observations and DNA sequences data indicated that strain NTU 568 and BCRC 31615 were the same species but not same strain. Further study using strain NTU 568 was employed. The approaches of this research are investigating on arise the secondary metabolites by different substrates and the effects of Monascus-fermented products on improvement diabetes symptoms in animal model. In the current study, we examined the effect of Monascus fermented products (red mold rice, red mold adlay and red mold dioscorea) on oral glucose tolerance testing in streptozotocin-induced diabetic Wistar rats. After 8-weeks feeding with Monascus fermented products at a dose of 200 mg/kg, the experimental results indicated that Monascus fermented products could delay the development of plasma glucose level in diabetic rats. Diabetes shares a common pathophysiology that may be explained as a consequence of hyperglycemia-mediated over-production of reactive oxygen species. The diabetic control rats showed higher reactive oxygen species and lower activities of glutathione disulfide-reductase, glutathione reductase and catalase in pancreas as compared to Monascus fermented products-treated rats. The results indicated that Monascus fermented products not only regulate hyperglycemia but also provide the preventive Hypothetical diagram on the antidiabetic/antioxidative/anti-inflammatory effects of red mold fermented products. effects of STZ-induced pancreatic damage. Red mold dioscorea has better effect than red mold rice and red mold adlay. Diabetic complications have demonstrated that the production of excess reactive oxygen species and inflammatory factors. Both oxidative stress and inflammation play a major role in the development of tissue insulin resistance. Red mold dioscorea contains various antioxidants considered useful for the treatment of diabetes. Throughout the experimental period, significantly lowered plasma glucose, triglyceride, cholesterol, free fatty acid and low density lipoprotein levels were observed in the red mold dioscorea-treated groups. Red mold dioscorea also inhibited diabetes-induced elevation in the levels of interleukin (IL)-1β, IL-6, interferon-γ and tumor necrosis factor-α. These results indicate that red mold dioscorea could attenuate diabetes and thus, minimize diabetic complications via the combination of its anti-hyperglycemia, anti-oxidative and anti-inflammatory effects. Monascus will be developed as a multi-functional food in the future.