Identification and characterization of phenolic antioxidant compounds from brown Irish seaweed Himanthalia elongata using LC-DAD–ESI-MS/MS

Abstract

This study investigated Himanthalia elongata Irish seaweed as a natural resource for antioxidant compounds. The phenolic compounds from the seaweed were extracted using 60% (v/v) aqueous methanol and the crude methanolic extract was purified with liquid–liquid partition (LLP) followed by column chromatography (CC). Among the purified fractions/sub-fractions, LLP-CC-ethyl acetate sub-fraction exhibited the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging (EC50, 2.4 mg/g) and lipid peroxidation (LPO) scavenging capacity (97.7%). Rapid characterization of the same sub-fraction by LC-DAD–ESI-MS/MS identified a total of 8 phenolic compounds namely hydroxybenzaldehyde (meta/para), phloroglucinol, kaempferol, cirsimaritin, gallic acid 4-O-glucoside, carnosic acid and gallic acid. The purified sub-fractions showed higher antioxidant capacity (P < 0.05) than the reference ascorbic acid, suggesting its possible application in foods, pharmaceuticals and cosmetics for health promotion. Contributions of the study include identification of compounds (except gallic acid) that have not previously been reported in H. elongata, identifying it as a rich source of phenolic antioxidant compounds. According to the CE 258/97 regulation, algae are considered as new foods, and could also be considered as functional foods or a source of functional ingredients. This regulation allows the food industry to include seaweeds as raw or its constituents in the formulation of food products. Therefore, much attention nowadays has been focused on harnessing seaweed and its bioactive compounds for potential pharmaceuticals, nutraceutical, cosmetics and biotechnology applications. This study explores the potential of H. elongata Irish seaweed as a natural source of commercially important antioxidant compounds for possible application in food and dietary supplementation products. The crude extract is first purified and then the most active fraction was characterized further. The identified phenolic antioxidant compounds can constitute a new move in the understanding of the health benefits of H. elongata seaweed and the species can be considered as substantial alternate for functional ingredients in food and medicinal preparations.