Comparison of different extraction techniques for obtaining extracts from brown seaweeds and their potential effects as angiotensin I-converting enzyme (ACE) inhibitors

Abstract

An extraction protocol was developed to maximize the amount of extracts obtained from three brown seaweeds, Lessonia nigrescens (in two stages of development), Macrocystis pyrifera, and Durvillaea antarctica, and to evaluate them as natural inhibitors of the angiotensin I-converting enzyme (ACE). Two extraction methods were used, an enzymatic method (cellulase and α-amylase) and a conventional method (maceration). The extracts were analyzed to determine the extraction yield (%), the total phenolic and carbohydrate concentrations, and the ACE inhibition. Juvenile L. nigrescens extracts obtained by α-amylase exhibited the highest extraction yield (37.72 ± 4.13 %), the highest ACE inhibition (95.61 ± 0.33 %), and the lowest IC50 (10.10 ± 1.55 μg PGE mg−1 seaweed) among the studied extracts. Extraction by maceration produced extracts with chemical characteristics that were less favorable for inhibiting ACE than the enzymatic extraction. The presence of phlorotannins and carbohydrates in these brown seaweeds after enzymatic extraction could be responsible for the superior ACE inhibitory activity of the extracts. Thus, these molecules could be considered as potential phytopharmaceuticals for the development of new ACE inhibitors.