以體外及體內模式探討薏仁麩皮萃取物減緩第二型糖尿病的效用及其作用機制

Abstract

糖尿病是一種因體內胰島素缺乏或功能不全而導致體內長期處於高血糖的慢性代謝疾病。臨床上雖已有許多口服降血糖藥物，但有其使用限制且伴隨副作用的疑慮，因此從傳統食材尋找更多延緩糖尿病之標的是目前的研究趨勢。薏仁(Coix lacryma-jobi L.var. ma-yuen Stapf.)，自古即被認為是藥食兼用的材料，具有抗發炎、降血脂、降血糖等生理功能，是藥性溫和的保健食材。薏仁麩皮(adlay bran, AB)占糙薏仁的7%，是加工過程重要的副產物，AB富含蛋白質、脂質、膳食纖維及生物活性物質，如酚類化合物和植物固醇，本研究目的是以體內與體外研究方法探討薏仁油(Oil)及脫脂薏仁麩皮水萃物(DABW)抗糖尿病的效用及其調節血糖的機制。本研究第一部分體內試驗-預防模式，探討不同薏仁麩皮萃取物是否能預防糖尿病之病徵。實驗結果顯示，高劑量薏仁油(Oil-H)能透過影響肝臟葡萄糖代謝，有效降低高血糖的情況。第二部分則以體內試驗-治療模式，探討高劑量薏仁油 (Oil-H)及脫脂薏仁麩皮水萃物(DABW-H)抗糖尿病之效用。結果顯示，DABW能有效降低發炎相關因子，進而達到調節血糖之功效。我們同時利用肌肉細胞(L6)胰島素阻抗模式進一步探討薏仁麩皮水萃物是否能刺激肌肉細胞之葡萄糖攝取，結果發現在胰島素阻抗模式下，脫脂薏仁麩皮水萃物與胰島素共同處理，有促進肌肉細胞葡萄糖攝取之趨勢，推測其可能提高胰島素敏感性而達此效果。綜上所述，在不同時間點介入薏仁麩皮萃取物，對於調降血糖之潛力與機制有不同程度之正面影響。本篇研究期望能透過提升薏仁麩皮的機能性及應用性，達到廢棄物再利用之目的。

Diabetes is a chronic metabolic disease caused by long-term hyperglycemia as a result of insulin insufficiency or dysfunction. Many oral hypoglycemic drugs are available currently, but not without limitations and side effects. Thus, finding potential therapeutics for diabetes from traditional foods has become the main trend. Adlay (Coix lachryma-jobi L.var. ma-yuen Stapf.) has been used as both food and medicine, and has proven to exhibit anti-inflammatory, hypolipidemic, and hypoglycemic effects. A significant by-product during adlay processing, adlay bran (AB) constitutes 7% of dehulled adlay and is rich in proteins, lipids, dietary fiber, and bioactive compounds such as phenolics and phytosterols. The present study involves in vivo and in vitro investigations of ameliorating effects on diabetes of adlay bran oil (Oil) and defatted adlay bran water extract (DABW) and the underlying mechanisms. The first part of this thesis investigates the in vivo preventive effects of adlay bran extracts on diabetes. The results show that high-dose Oil can lower high blood glucose by affecting hepatic glucose metabolism. The second part investigates the in vivo attenuating effects of the defatted adlay bran extracts on diabetes. The results indicate DABW can regulate blood glucose by reducing inflammatory factors. Furthermore, in an insulin-resistant L6 myoblast cell model, DABW is found to potently increase muscle glucose uptake, possibly increasing insulin sensitivity. In summary, different time-course dietary interventions of adlay bran extracts result in differing effects on diabetic symptoms through varying mechanisms. This study hopes to explore more functions and applications of adlay bran to achieve by-product recycling.