A phlorotannin constituent of Ecklonia cava alleviates postprandial hyperglycemia in diabetic mice. (1st January 2017) - Lee, Hyun-Ah
Abstract: Context : 2, 7″-Phloroglucinol-6, 6′-bieckol is a type of phlorotannin isolated from brown algae, Ecklonia cava Kjellman (Phaeophyceae; Laminareaceae). 2, 7″-Phloroglucinol-6, 6′-bieckol mediates antioxidant activities. However, there has been no research on improving postprandial hyperglycaemia using 2, 7″-phloroglucinol-6, 6′-bieckol. Objective: This study investigated the inhibitory effects of 2, 7″-phloroglucinol-6, 6′-bieckol on activities of α-glucosidase and α-amylase as well as its alleviating effect on postprandial hyperglycaemia in streptozotocin-induced diabetic mice. Materials and methods: α-Glucosidase and α-amylase inhibitory assays were carried out. The effect of 2, 7″-phloroglucinol-6, 6′-bieckol on hyperglycaemia after a meal was measured by postprandial blood glucose in streptozotocin-induced diabetic and normal mice. The mice were treated orally with soluble starch (2 g/kg BW) alone (control) or with 2, 7″-phloroglucinol-6, 6′-bieckol (10 mg/kg bw) or acarbose (10 mg/kg BW) dissolved in 0.2 mL water. Blood samples were taken from tail veins at 0, 30, 60, and 120 min and blood glucose was measured by a glucometer. Results: 2, 7″-Phloroglucinol-6, 6′-bieckol showed higher inhibitory activities than acarbose, a positive control against α-glucosidase and α-amylase. The IC50 values of 2, 7″-phloroglucinol-6, 6′-bieckol against α-glucosidase and α-amylase were 23.35 and 6.94 μM, respectively, which was found more effective than observed with acarbose (α-glucosidase IC50 of 130.04 μM; α-amylase IC50 of 165.12 μM). In normal mice, 2, 7″-phloroglucinol-6, 6′-bieckol significantly suppressed the postprandial hyperglycaemia caused by starch. The 2, 7″-phloroglucinol-6, 6′-bieckol administration group (2349.3 mmol·min/L) had a lower area under the curve (AUC) glucose response than the control group (2690.83 mmol·min/L) in diabetic mice. Discussion and conclusion: 2, 7″-Phloroglucinol-6, 6′-bieckol might be used as an inhibitor of α-glucosidase and α-amylase as well as to delay absorption of dietary carbohydrates.