Identification of antiplatelet and acetylcholinesterase inhibitory constituents in betel nut

Objective: To investigate the possible mechanism and the compound (s) responsible for the antiplatelet and acetylcholinesterase (AChE) inhibitory effects of Areca catechu crude extract (Ac. Cr). Methods: Aqueous-methanol (70%) was used for extraction of plant material (betel nut). Antiplatelet activity was measured in human platelet-rich plasma by using a Lumi-aggregometer while anti-AChE activity was measured spectrophotometrically in vitro. In an attempt to find the responsible compound(s) in betel nut for antiplatelet and anti-AChE activities, different commercially available betel nut compounds were tested. Results: Ac. Cr inhibited platelet aggregation induced by arachidonic acid (AA), adenosine diphosphate (ADP), platelet-activating factor (PAF), epinephrine and Ca²⁺-ionophore. Ac. Cr was the most potent in inhibiting ADP- and Ca²⁺-ionophore-induced aggregation. In the AChE assay, Ac. Cr showed significant AChE inhibitory activity with almost complete inhibition of the enzyme. Out of the tested compounds, none of the compounds in betel nut showed any antiplatelet effect except for catechin that was the most potent against epinephrine-induced aggregation. Catechin was significantly less potent than Ac. Cr, indicating a presence of additional compound (s) with antiplatelet activity. For the AChE inhibitory effect, only tannic acid, gallic acid, diosgenin and isoguvacine were found to be active, whereby tannic acid was more potent than Ac. Cr. Conclusion: This study shows the possible antiplatelet and AChE inhibitory potential of betel nut while further studies are needed to confirm and identify more compounds in betel nut for these actions.