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. 2016:2016:9139731.
doi: 10.1155/2016/9139731. Epub 2016 Dec 22.

The Peroxidation of Leukocytes Index Ratio Reveals the Prooxidant Effect of Green Tea Extract

Ilaria Peluso  1 , Husseen Manafikhi  2 , Anna Raguzzini  1 , Yaroslava Longhitano  2 , Raffaella Reggi  2 , Christian Zanza  2 , Maura Palmery  2
Affiliations

The Peroxidation of Leukocytes Index Ratio Reveals the Prooxidant Effect of Green Tea Extract

Ilaria Peluso et al. Oxid Med Cell Longev. 2016.

Abstract

Despite tea increased plasma nonenzymatic antioxidant capacity, the European Food Safety Administration (EFSA) denied claims related to tea and its protection from oxidative damage. Furthermore, the Supplement Information Expert Committee (DSI EC) expressed some doubts on the safety of green tea extract (GTE). We performed a pilot study in order to evaluate the effect of a single dose of two capsules of a GTE supplement (200 mg × 2) on the peroxidation of leukocytes index ratio (PLIR) in relation to uric acid (UA) and ferric reducing antioxidant potential (FRAP), as well as the sample size to reach statistical significance. GTE induced a prooxidant effect on leukocytes, whereas FRAP did not change, in agreement with the EFSA and the DSI EC conclusions. Besides, our results confirm the primary role of UA in the antioxidant defences. The ratio based calculation of the PLIR reduced the sample size to reach statistical significance, compared to the resistance to an exogenous oxidative stress and to the functional capacity of oxidative burst. Therefore, PLIR could be a sensitive marker of redox status.

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Conflict of interest statement

The authors declare that there is no conflict of interests regarding the publication of this paper.

Figures

Figure 1
Figure 1
Typical overlay dot plots of ratio (ratio of oxidation of the probe C11-BODIPY: FL1/FL2) versus side scatter (SSC): before (T0) and 3 hours (T3) in leukocytes collected after a single dose of two capsules of a green tea extract (GTE) supplement (200 mg × 2). L: lymphocytes, M: monocytes, and G: granulocytes. Unstimulated samples (black) and leukocytes treated with 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH, 10 mM, red), AAPH (10 mM) + 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox, 10 μM, yellow), phorbol 12-myristate 13-acetate (PMA, 1 μg/mL, blue), or PMA (1 μg/mL) + Trolox (green).
Figure 2
Figure 2
Ratio (ratio of oxidation of the probe C11-BODIPY: FL1/FL2) of monocytes (a) and granulocytes (b), in samples collected from 10 healthy subjects before (T0) and 3 hours (T3) after the consumption of a single dose of two capsules of a green tea extract (GTE) supplement (200 mg × 2). Cells unstimulated (UNST) or treated with phorbol 12-myristate 13-acetate (PMA, 1 μg/mL), 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH, 10 mM), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox, 10 μM), Trolox + PMA, or Trolox + AAPH. Two-way (2W) RM ANOVA, with time and treatment as within-subjects factors, followed by Student-Newman-Keuls post hoc analysis: AAPH versus PMA within time: ∗∗ p < 0.01, ∗∗∗ p < 0.001.
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