Epigallocatechin Gallate: pH-Dependent Redox Properties and Effect on Respiration, Photosynthesis, and Cell Death in Pea Plants

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Dmitry B. Kiselevsky^1,a*, Olga V. Samuilova², and Vitaly D. Samuilov¹

¹Department of Immunology, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia

²Department of Biological Chemistry, Institute of Biodesign and Modeling of Complex Systems, Sechenov First Moscow State Medical University, 119991 Moscow, Russia

^* To whom correspondence should be addressed.

Received November 16, 2022; Revised January 12, 2023; Accepted January 13, 2023

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In vitro redox properties of the green tea component epigallocatechin gallate (EGCG) and its effect on pea plant cells were investigated. EGCG was found to exhibit both pro- and antioxidant properties. In solutions, EGCG was oxidized by oxygen at physiological (slightly alkaline) pH values with the generation of O₂^–• and H₂O₂, the reaction being slowed down by a decrease in the medium pH. On the other hand, EGCG functioned as an electron donor for peroxidase, resulting in the H₂O₂ utilization. EGCG suppressed respiration, reduced mitochondrial transmembrane potential difference and inhibited electron transfer in the photosynthetic electron transport chain in pea leaf cells (leaf cuttings and epidermis). Among components of the photosynthetic redox chain, Photosystem II was the least sensitive to the EGCG action. In the epidermis, EGCG reduced the rate of reactive oxygen species formation that was induced by NADH. EGCG at the concentrations from 10 μM to 1 mM suppressed the KCN-induced death of guard cells in the epidermis, which was determined from the destruction of cell nuclei. EGCG at a concentration of 10 mM disrupted the barrier function of the guard cell plasma membrane, increasing its permeability to propidium iodide.

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KEY WORDS: EGCG, peroxidase, reactive oxygen species, cell death, pea

DOI: 10.1134/S0006297923020050

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