Anticholinesterase Activities of Selected Polyphenols - a Short Report

In this work, anticholinesterase activities of 24 polyphenolic compounds were tested using the modified Ellman's spectrophotometric method. The most efficient acetyl-and butyrylcholinesterase inhibitors were anthocyanins (pelargonidin, delphinidin and cyanidin), flavones (apigenin and luteolin), flavonols (quercetin, kaempferol and myricetin), as well as dihydrochalcone phloridzin and prenylated chalcone xanthohumol. It was established that all the tested compounds were within a narrow molecular weight range of 254.24-354.40 g/mol, which probably was not discriminative for their inhibitory activity. Among all the classes of polyphenolic compounds, the lowest activities were exerted by flavan-3-ols. The inhibitory activity of the tested polyphenols was decreased by the presence of a 3-hydroxyl group. A simultaneous substitution of a carbonyl group at position 4 and a hydroxyl group at position 3 or a lack of both of these substitutions had no effect on the activity of the investigated compounds. The number and position of other hydroxyl groups in the tested molecules played a minor role in this context. Aglycons were more effective cholinesterase inhibitors than their corresponding glycosylated forms. Overall, the results show that phenolic acids can play a role in neuroprotection. However, further in vitro and in vivo studies involving a larger number of polyphenolic compounds simultaneously with well-known cholinesterase inhibitors should be performed in the nearest future to confirm these findings.