Antihyperglycemic and anti-type 2 diabetic activity of marine hydroquinone isolated from brown algae (Dictyopteris polypodioides).

Abstract

Brown algae (Dictyopteris polypodioides) extract (DP) presented high inhibitory potential against α-amylase. The present study aims to isolate, purify and evaluate the antihyperglycemic and anti-type 2 diabetic activities of marine hydroquinone from DP. Marine hydroquinones were isolated using silica gel, HPLC, and NMR spectroscopy was used to identify compound 1 and compound 2 as zonarol and isozonarol, respectively. The anti-hyperglycemic and anti-type 2 diabetic activities of zonarol were investigated by invitro assay (α-amylase, α-glucosidase), Lineweaver-Burk plot and Type 2 diabetes mellitus model (T2DM) mice induced by streptozotocin (STZ). Zonarol had the highest content and the strongest inhibitory activity against α-glucosidase (IC50 value of 6.03mgL-1) and α-amylase (IC50 value of 19.29mgL-1) in a competitive inhibition and mix-type manner, respectively. The maltose and starch loading tests revealed that zonarol significantly reduced postprandial glycemia after 30min loading (9.12 and 8.12mg/dL, respectively), compared to normal (11.37 and 12.37mg/dL, respectively). Zonarol exhibited pancreatic islet cell rejuvenation, as evidenced by increased pancreatic islet mass, and hence helps in the restoration of insulin levels and therefore improves the glucose metabolism in STZ-induced diabetic mice. Zonarol treatment in T2DM elevated abundant levels of main SCFAs (propionate, butyrate, and valeric acid), which are closely related to glucose metabolism homeostasis. Our finding indicates that zonarol could be used as a food supplement to treat hyperglycemia and diabetes.