The biological activities of the branch bark ethanol extract (BBEE) in the mulberry Morus alba L. were investigated. The determination of active component showed that the flavonoids, phenols, and saccharides are the major components of the ethanol extract. The BBEE had a good scavenging activity of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical with around 100？μg/mL of IC50 value. In vitro assay revealed that the BBEE strongly inhibited both α-glucosidase and sucrase activities whose IC50 values were 8.0 and 0.24？μg/mL, respectively. The kinetic analysis showed that the BBEE as a kind of α-glucosidase inhibitor characterized a competitive inhibition activity. Furthermore, the carbohydrate tolerance of the normal mice was obviously enhanced at 0.5？h and 1.0？h after the BBEE intragastric administration as compared to negative control. At 0.5, 1.0, 1.5, and 2.0？h after the intragastric administration with starch, the postprandial hyperglycemia of the type 2 diabetic mice can be significantly decreased by supplying various concentrations of the BBEE (10–40？mg/kg body weight). Therefore, the BBEE could effectively inhibit the postprandial hyperglycemia as a novel α-glucosidase activity inhibitor for the diabetic therapy. 1. Introduction Diabetes mellitus is a metabolic disorder characterized by a congenital (type 1 insulin-dependent diabetes mellitus/IDDM) or acquired (type 2 noninsulin-dependent diabetes mellitus/NIDDM) inability to transport glucose from the bloodstream into cells. The type 1 is usually diagnosed in childhood, and the body makes little or no insulin. The type 2 diabetes is an insulin resistance condition that occurs in adulthood, and it afflicts approximately 90% of all diabetics. The most beneficial therapy for the type 2 is said to be one that achieves optimal blood glucose control after a meal [1]. Now the pharmacological agents with the greatest effect on postprandial hyperglycemia included insulin, lispro, amylin analogues, and α-glucosidase inhibitors such as Acarbose, Voglibose, Miglitol, and Emiglitate [2] in which Acarbose had been extensively used in clinical practice. But the oral hypoglycemic agents currently used in clinical practice have serious side effects [3]. Management of hyperglycemia or hyperlipidemia with low side effects is still a challenge to the current medical system. Hence, there is a need to search for newer antidiabetic agents that retain therapeutic efficacy and are devoid of side effects. It is necessary to identify and have a large pool of the natural resources. There were many articles related to
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