Phenolic acids from malt are efficient acetylcholinesterase and butyrylcholinesterase inhibitors

Abstract

Anticholinesterase activities of mashes produced using wheat ('Wheat Pale') or barley malts ('Pilsner', 'Pale Ale', 'Munich Light', 'Carahell' or 'Carared') were studied by spectrophotometric method. The highest inhibition of acetylcholinesterase and butyrylcholinesterase was observed at 52°C and/or 64°C, followed by a decrease or stabilization of the activity at 72°C. Changes in the total phenolics content in the test mashes were correlated with changes in the acetylcholinesterase and/or butyrylcholinesterase activities. Phenolic acids were singled out from phenolic compounds for more detailed studies owing to their simplicity and structural similarity to well-known cholinesterase inhibitors. The main phenolic acids in the test malts were ferulic, gallic, p-coumaric and vanillic acids followed by chlorogenic, caffeic, syringic, p-OH-benzoic, sinapic and protocatechuic acids. The anticholinesterase activities of the phenolic acids were studied using model standard solutions at concentrations similar to the maximal content of these compounds in the test mashes. Among the phenolic acids, p-coumaric acid had the largest share in the anticholinesterase activity, even though it was present in the test mashes at a significantly lower concentration (~0.38mM L-1) than ferulic acid (~1.00mM L-1). Sinapic acid and p-OH-benzoic acid (0.03 and 0.01mM L-1, respectively) were equally efficient inhibitors as ferulic acid at ~1.00mM L-1. This preliminary study should be extended to other phenolic compounds from malt (wort) in the near future. © 2012 The Institute of Brewing & Distilling.