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Aqueous–ethanol extracts of some South African seaweeds inhibit beta‐amyloid aggregation, cholinesterases, and beta‐secretase activities in vitro

Olasehinde, Tosin A., Olaniran, Ademola O., Okoh, Anthony I.
Journal of food biochemistry 2019 v.43 no.7 pp. e12870
Alzheimer disease, Ecklonia, Gelidium, Gracilaria, Ulva lactuca, acetylcholinesterase, amyloid, antioxidant activity, bioactive compounds, cholinesterase, cosmetics, dietary supplements, dose response, enzyme activity, enzyme inhibition, functional foods, hydroxyl radicals, iron, macroalgae, neuroprotective effect, peptides, plant extracts
In this study, we evaluated the anti‐amyloidogenic, anticholinesterase, and antioxidant potentials of hydroethanolic extracts of Ecklonia maxima (ECK), Gelidium pristoides (GLD), Gracilaria gracilis (GCL), and Ulva lactuca (ULT). The effect of the extracts on β‐amyloid (Aβ₁‐₄₂) peptide were determined using electron microscope. The effects of the extracts on β‐secretase and cholinesterase activities, as well as their radical scavenging and metal chelating activities were also assessed. Electron micrographs revealed that ECK, GLD, GCL, and ULT incubated with Aβ₁‐₄₂ at different intervals (0–96 hr) showed very low levels of fibrils compared to the control. The extracts also inhibited β‐secretase, acetylcholinesterase, and butyrylcholinesterase activities in a dose‐dependent manner. Furthermore, the extracts scavenged hydroxyl radicals and were able to chelate Fe²⁺ in a dose‐dependent manner. Our findings suggest that the seaweed extracts are potential sources of lead compounds and novel inhibitors of β‐amyloid aggregation, β‐secretase, and cholinesterases for the management of Alzheimer's diseases. PRACTICAL APPLICATIONS: Seaweeds have been identified as good sources of naturally occurring bioactive compounds with several medicinal properties. They are commonly used as functional foods and development of nutraceuticals, dietary supplements, and cosmeceuticals. However, the neuroprotective effects of many species of seaweeds have not been fully explored. The findings of this study suggests that Gracilaria gracilis, Ulva lactuca, Ecklonia maxima, and Gelidium pristoides are potential sources of cholinesterase, beta‐secretase, and amyloid protein aggregation inhibitors. Hence, this support the use of these seaweeds as alternative sources of antioxidants and natural compounds with neuroprotective potentials for the management of Alzheimer's disease.