Phlorotannins from Fucales: potential to control hyperglycemia and diabetes-related vascular complications

Abstract

Key enzymes implicated in the metabolism of carbohydrates, such as the pancreatic α-amylase and the intestinal α-glucosidase, are the main targets of drugs designed to avoid and control hyperglycemia in diabetes mellitus. Phlorotannin-targeted extracts from four edible Fucus species, whose composition was previously established by mass spectrometry-based techniques (HPLC-DAD-ESI/MSn and UPLC-ESI-QTOF/MS), were able to inhibit both α-amylase and α-glucosidase carbohydrate-metabolizing enzymes, though being more effective towards the latter, with IC50 values significantly lower than those obtained for the pharmacological inhibitors acarbose and miglitol. The extracts also inhibited xanthine oxidase (XO), an enzymatic system usually overexpressed in diabetes and responsible for producing deleterious free radicals, such as superoxide anion radical (O2•-). Only Fucus guiryi and Fucus serratus extracts were able to scavenge O2•- under the tested concentrations. The biological potential displayed by the extracts was correlated with the total phlorotannin content. This is a pioneer study on the capacity of phlorotannin-targeted extracts from Fucus spp. to inhibit α-amylase, α-glucosidase, and XO, with special focus on enzyme kinetics, contributing for the valorization of the selected edible seaweeds and encouraging their incorporation in nutraceuticals and/or pharmaceuticals for glycemic control and to avoid the onset of diabetes-related vascular complications associated to oxidative stress.