Anti-glycation effects of brown algae extracts and its phenolic compounds

In this study, 50% (v/v) ethanolic extracts from 12 brown algae species were investigated for their antiglycation effects. Three glycation models, namely (bovine serum albumin with fructose [Fru-BSA], glyoxal [BSA-GO], and methylglyoxal [BSA-MGO]) were used for screening. Ecklonia cava (Ec), Leathesia difformis (Ld), and Dictyota dichotoma (Dd) exhibited the highest levels of advanced glycation end-product (AGE) inhibition in the Fru-BSA model. Ec exhibited the highest levels of advanced glycation end-product (AGE) inhibition in the BSA-MGO and BSA-GO models. Further, Ec extract exhibited the highest total antioxidant activity and phenolic content. The phenolic compounds in the extracts were identified using high-performance liquid chromatography. The AGE inhibition effects of the identified phenolic compounds (dieckol, phlorofucofuroeckol-A, gallic acid, catechin, and quercetin) were measured to evaluate the predominant AGE inhibitor among the phenolic compounds. Among the standard phenolic compounds, phlorofucofuroeckol-A and dieckol exhibited lower IC₅₀ values in the BSA-GO and BSA-MGO models. Pearson's correlation analyses showed that dieckol, phlorofucofuroeckol-A, and quercetin in the extracts were positively correlated with BSA-MGO (r > 0.90, p < 0.001) and BSA-GO (r > 0.84, p < 0.001), whereas no significant correlation was observed between other phenolic compounds (gallic acid and catethin) and AGE inhibition effects. The findings of this study suggest that Ec extract is a suitable natural source of antiglycation agents, and that dieckol is its predominant AGE inhibitor.