研究報告：Preventive Effects of Mulberry Leaves on Metabolic Disorder448
Preventive Effects of Mulberry Leaves on Metabolic Disorder
Tin-Chen Hsu1,2; William Hsu3; H. Tominaga4; Y. Matsui5; H. Kondo5; & K. Suzuki6
1Institute of Food Science & Technology, National Taiwan University, Taipei, Taiwan; 2Chien-Cheng Trading Co., Ltd., Taipei, Taiwan; 3Taipei American School, Taipei, Taiwan; 4Toyotama International Inc., Tokyo, Japan; 5Toyotama Health Food Co., Ltd., Tokyo, Japan; 6Iwate University, Morioka, Japan
Mulberry leaves has been used as a tea beverage in Japan for people with concerns in sugar intakes while its root bark is applied in Chinese remedies for diabetic, antipyretic, antitussive and diuretic purposes. Recent research, by Department of Food and Drug, Kanagawa Prefectural Institute of Public Health in Japan, has revealed that mulberry leaves have preventive effects on life-related disorder and many functional characteristics as food materials.
Mulberry leaves contain 1-deoxynojirimycin (DNJ), a functional ingredient, in addition to flavonoid and other essential minerals like calcium, magnesium, iron and zinc. Due to its structural similarity to glucose, DNJ functions as a competitive inhibitor for α-glucosidase, a carbohydrate-digesting enzyme for sucrose & maltose in small intestine of mammals. Therefore, mulberry leaves was shown to effectively control the rapid-rise of blood glucose after meal in a dose-dependent manner and assist in prevention of diabetes via DNJ, suggesting its preventive and therapeutic activities in control of blood sugar. In addition, treatments by mulberry leaves were shown to significantly improve the fasting blood glucose and HbA1c as compared to treatment by glibenclamide, an anti-diabetic drugs.
Mulberry leaves also regulate lipid metabolism by reducing triglycerides, total cholesterol and, consequently, atheromatous thickening of blood vessel via decrease in LDL-cholesterol and increase in HDL-cholesterol in diabetic patients. Suppressive effect of mulberry leaves on blood pressure was examined by using spontaneously hypertensive rats, where mulberry leaves-containing diet reduced blood pressure of the hypertensive rats, while the same diet shows no effects on blood pressure for normal rats.
Our study shows therapeutic effects of mulberry leaves and DNJ, its functional component, in the glycemic and lipid control of patient with type 2 diabetics. In addition to DNJ, mulberry leaves also contain various compounds for supporting good health including Amino acids (γ-Aminobutyric acid & Alanine), Flavonoids (Isoquercitrin, Astragalin, Quercetin & Quercitrin), Sterols (Sitosterol & Sigmasterol), and minerals (Calcium, Potassium & Iron), all assisting in maintaining health conditions.
Key words: Mulberry leaves, DNJ, Metabolic disorder