In vitro potential of ascophyllum nodosum phenolic antioxidant-mediated α-glucosidase and α-amylase inhibition

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Ascophyllum nodosum is a brown seaweed that grows abundantly in the Northeast coastal region. In this study, the potential of A. nodosum for type 2 diabetes management through antioxidant-mediated α-glucosidase and α-amylase inhibition was investigated. After the initial screening of 4 locally harvested seaweeds, A. nodosum was chosen for its highest phenolic content and was subjected to water extraction. Among extraction ratios of 50 g to 100 to 1000 mL at room temperature, 50 g/400 mL yielded the highest phenolic content of 4.5 mg/g wet weight. For evaluation of extraction temperature ranging from 20 to 80 °C, 50 g/400 mL was chosen as a minimum amount of extractant. Among temperatures studied, extraction at 80 °C resulted in the highest total phenolic contents (4.2 mg/g wet weight). All extracts had similar levels of antioxidant activity in the range of 60% to 70% in terms of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. The 80 °C extract had the highest α-glucosidase and α-amylase inhibitory activity with IC50 of 0.24 and 1.34 μg phenolics, respectively, compared to the IC50 of acarbose, reference inhibitor, being 0.37 and 0.68 μg. The results show that fresh A. nodosum has strong α-glucosidase and mild α-amylase inhibitory activities that correlated with phenolic contents. This study suggests a nutraceutical potential of A. nodosum based on phytochemical antioxidant and antihyperglycemia activities. © 2010 Institute of Food Technologists®.

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Journal of Food Science