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Antioxidant and Acetylcholinesterase Inhibiting Activity of Several Aqueous Tea Infusions in vitro

We present a study of antioxidant activity and acetylcholinesterase (AChE) inhibitory activity of aqueous tea infusions prepared from walnut (Juglans regia L.), peppermint (Mentha piperita L.), strawberry (Fragaria ananassa L.), lemon balm (Melissa officinalis L.), sage (Salvia officinalis L.), and immortelle (Helichrysum arenarium (L.) Moench). Chemical composition of selected aqueous tea infusions was determined by HPLC-PDA, and the following phenolic compounds have been identified as dominant: rosmarinic acid, gallic acid (not identified in walnut and sage), caffeic acid (in sage and peppermint), neochlorogenic acid, 3-p-coumaroylquinic acid and quercetin-3-galactoside (in walnut) and luteolin-7-glucoside (in sage). Antioxidant activity of selected aqueous tea infusions was measured using LDL (low-density lipoprotein) oxidation method, the DPPH (2, 2 -diphenyl-1-picrylhydrazyl) radical scavenging test, the  -carotene bleaching method, and Rancimat method (induction period of lard oxidation). Strawberry and lemon balm aqueous infusions completely inhibited LDL oxidation at the concentration of 0.005 g/L in reacting system. Very long prolongation of the lag phase was achieved with peppermint and sage aqueous infusions. All tested infusions in the concentration range of 0.05-2.85 g/L showed very pronounced effect of DPPH scavenging activity (90-100%) as well as the inhibition of the β -carotene bleaching (89-100%). In pure lipid medium, used in Rancimat method, sage and immortelle at the concentration of 0.16% (w/w) have the highest ability to inhibit lipid peroxidation process. Screening of the AChE inhibitory activity by Ellman´s method is the strongest in walnut and strawberry aqueous infusions at the concentration of 1.36 g/L in reacting system. Presented results suggest that natural antioxidants could be useful and merit further investigations in the treatment and the prevention of Alzheimer’ s disease.

antioxidant; acetylcholinesterase inhibiting activity; aqueous tea infusion; phenolic compounds

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