Antioxidant and Acetylcholinesterase Inhibiting Activity of Several Aqueous Tea Infusions in vitro
Tea Kulišić-Bilušić1*, Višnja Katalinić1, Verica Dragović-Uzelac2, Ivica Ljubenkov3, Anita Kriško4, Branka Dejanović4, Mila Jukić1, Olivera Politeo1, Greta Pifat4 and Mladen Miloš1
1Faculty of Chemistry and Technology, University of Split, Teslina 10/V, HR-21 000 Split, Croatia
2Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10 000 Zagreb, Croatia
3Nutrition Development Center – SMS, Kurtovići bb, HR-21 231 Klis, Croatia
4Rudjer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia
Article history:
Received November 29, 2007
Accepted March 4, 2008
Key words:
antioxidant activity, acetylcholinesterase inhibiting activity, aqueous tea infusion, phenolic compounds
Summary:
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.) is presented here. Chemical composition of selected aqueous tea infusions was determined by high-performance liquid chromatography with photodiode-array method (HPLC-PDA), and the following phenolic compounds were 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-O-glucoside (in sage). Antioxidant activity of the selected aqueous tea infusions was measured using low-density lipoprotein (LDL) oxidation method, 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging test, β-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 the 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 β-carotene bleaching (89–100 %). In pure lipid medium, used in Rancimat method, sage and immortelle at the concentration of 0.16 % (by mass) had the highest ability to inhibit lipid peroxidation process. Screening of the AChE inhibitory activity by Ellman´s method showed that the strongest inhibition was obtained with walnut and strawberry aqueous infusions at the concentration of 1.36 g/L in the reacting system. The presented results suggest that natural antioxidants could be useful and merit further investigations in the treatment and prevention of Alzheimer’s disease.
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