Alaria esculenta, Ulva lactuca, and Palmaria palmata as Potential Functional Food Ingredients for the Management of Metabolic Syndrome

Hypertension, type 2 diabetes (T2D), and obesity raise an individual's risk of suffering from diseases associated with metabolic syndrome (MS). In humans, enzymes that play a role in the prevention and development of MS include angiotensin converting enzyme (ACE-1) associated with hypertension, α-amylase associated with T2D, and lipase linked to the development of obesity. Seaweeds are a rich source of bioactives consisting of proteins/peptides, polysaccharides, and lipids. This study examined the potential of seaweed-derived bioactives from <i>Alaria esculenta, Ulva lactuca</i>, and <i>Palmaria palmata</i> as inhibitors of ACE-1, α-amylase, and lipase. In vitro enzyme inhibitory assays were used to quantify the bioactivity of the seaweed extracts and compare their half-maximal inhibitory (IC₅₀) values to recognised positive control enzyme inhibitory drugs captopril© (an ACE-1 inhibitor), acarbose (an α-amylase inhibitor), and orlistat (a lipase inhibitor). Three seaweed extracts displayed enzyme inhibitory activities equal to, or more effective than, the reference positive control drugs. These were <i>P. palmata</i> peptides (ACE-1 IC₅₀ 94.29 ± 3.07 µg/mL, vs. captopril© 91.83 ± 2.68 µg/mL); <i>A. esculenta</i> polyphenol extract (α-amylase IC₅₀ 147.04 ± 9.72 µg/mL vs. acarbose 185.67 ± 12.48 µg/mL, and lipase IC₅₀ 106.21 ± 6.53 µg/mL vs. orlistat 139.74 ± 9.33 µg/mL); and <i>U. lactuca</i> polysaccharide extract (α-amylase IC₅₀ 168.06 ± 10.53 µg/mL vs. acarbose 185.67 ± 12.48 µg/mL). Proximate analysis also revealed that all three seaweeds were a good source of protein, fibre, and polyunsaturated essential fatty acids (PUFAs). These findings highlight the potential of these seaweeds in the management of diseases associated with MS and as foods.