Screening of Mexican tropical seaweeds as sources of α-amylase and α-glucosidase inhibitors

Abstract

A key therapeutic strategy to prevent metabolic syndrome is the inhibition of α-amylase and α-glucosidase. Derivatives isolated from naturally-sourced seaweeds may act as inhibitors of these enzymes. The aims of this study are to evaluate in vitro the α-amylase and α-glucosidase inhibition of 45 crude extracts from 31 species of Ochrophyta, Rhodophyta, and Chlorophyta present in Mexican seashores, describe their acute toxicity, and putatively identify some of the potential bioactive compounds by using untargeted metabolomics. Also, active extracts were evaluated in the brine shrimp lethality test. Samples were collected during rainy and dry seasons in the rocky shores of Paraíso, Villa Rica and Muñecos, in Veracruz, Mexico. Crude extracts were obtained by maceration and then tested on both enzymes. Chemical profiling was done by accurate mass spectrometry and data was analyzed using statistical tools. The results showed that seaweeds from Veracruz are sources of α-amylase and α-glucosidase inhibitors. The highest α-amylase and α-glucosidase inhibition (IC50 values) were observed in Cladophora dalmatica (116.99 ± 11.59, 27.86 ± 2.95 μg mL−1), Ectocarpus siliculosus (679 ± 68.17, 276.86 ± 11.20 μg mL−1), Padina boergesenii (567.01 ± 65.20, 43.89 ± 5.46 μg mL−1) and P. gymnospora (>1000, 59.92 ± 7.45 μg mL−1) species, respectively. Active extracts were more effective inhibitors of α-glucosidase compared to acarbose (>1000 μg mL−1), used as drug reference. C. dalmatica showed high toxicity (LC50 = 37.55 ± 1.04 μg mL−1), whilst the rest of the active extracts did not. Fatty acids and terpenoids were tentatively identified in the active extracts as potential inhibitors of tested enzymes. In conclusion, Mexican seaweeds constitute sources of metabolites that could reduce hyperglycemia postprandial by the inhibition of α-amylase and α-glucosidase. Ochrophyta species are the best sources to look for these inhibitors because their extracts are not toxic and displayed lower α-amylase inhibitory activities.