Effect of Brewing Duration on the Antioxidant and Hepatoprotective Abilities of Tea Phenolic and Alkaloid Compounds in a t-BHP Oxidative Stress-Induced Rat Hepatocyte Model.
Tea is an interesting source of antioxidants capable of counteracting the oxidative stress implicated in liver diseases. We investigated the impact of antioxidant molecules provided by a mixture of teas' leaves (green, oolong, pu-erh) after different infusion durations in the prevention of oxidative stress in isolated rat hepatocytes, by comparison with pure epigallocatechin-3-gallate (EGCG), the main representative of tea catechins. Dried aqueous tea extracts (ATE) obtained after 5, 15 and 30 min infusion time were characterized for total polyphenols (gallic acid equivalent), catechins, gallic acid and caffeine (HPLC-DAD/ESI-MS) contents, and for scavenging ability against 2,2-diphenyl-1-picrylhydrazyl free radical. Hepatoprotection was evaluated through hepatocyte viability tests using tert-butyl hydroperoxide as a stress inducer, (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, neutral red uptake, real-time cellular impedance) and mitochondrial function tests. We showed that a 5-min incubation time is sufficient for an optimal bioaccessibility of tea compounds with the highest antioxidative ability, which decreases for longer durations. A 4-h pretreatment of cells with ATE significantly prevented cell death by regulating reactive oxygen species production and maintaining mitochondrial integrity. Pure EGCG, at doses similar in ATE (5-12 µM), was inefficient, suggesting a plausible synergy of several water-soluble tea compounds to explain the ATE beneficial effects.
Laboratoire PROTEE, EB2M, Université de Toulon, CS 60 584, 83 041 Toulon Cedex, Campus La Garde, France. lbraud01@gmail.com.
Laura
L
Braud
UMR 1331 TOXALIM (Research Centre in Food Toxicology), Institut National de la Recherche Agronomique (INRA), Laboratory of Xenobiotic's Cellular and Molecular Toxicology, 400 Route des Chappes, 06903 Sophia-Antipolis, France.
Ludovic
L
Peyre
UMR 1331 TOXALIM (Research Centre in Food Toxicology), Institut National de la Recherche Agronomique (INRA), Laboratory of Xenobiotic's Cellular and Molecular Toxicology, 400 Route des Chappes, 06903 Sophia-Antipolis, France.
Georges
G
de Sousa
Aix-Marseille Université, CNRS, CRMBM UMR 7339, F-13385 Marseille, France.
Martine
M
Armand
UMR 1331 TOXALIM (Research Centre in Food Toxicology), Institut National de la Recherche Agronomique (INRA), Laboratory of Xenobiotic's Cellular and Molecular Toxicology, 400 Route des Chappes, 06903 Sophia-Antipolis, France.
Roger
R
Rahmani
Laboratoire PROTEE, EB2M, Université de Toulon, CS 60 584, 83 041 Toulon Cedex, Campus La Garde, France.
Jean-Michel
JM
Maixent
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002110:Caffeine / Q000494:pharmacology; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D022781:Hepatocytes / Q000187:drug effects / Q000473:pathology*; D008099:Liver / Q000187:drug effects; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D018384:Oxidative Stress / Q000187:drug effects*; D010636:Phenols / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology; D020011:Protective Agents / Q000494:pharmacology*; D051381:Rats; D021241:Spectrometry, Mass, Electrospray Ionization; D013481:Superoxides / Q000378:metabolism; D013662:Tea / Q000737:chemistry*; D013997:Time Factors; D020122:tert-Butylhydroperoxide / Q000633:toxicity
D000470:Alkaloids; D000975:Antioxidants; D010636:Phenols; D010936:Plant Extracts; D020011:Protective Agents; D013662:Tea; D013481:Superoxides; D002110:Caffeine; D002392:Catechin; D020122:tert-Butylhydroperoxide; C045651:epigallocatechin gallate
Camellia sinensis; EGCG; ROS; antioxidant; bioaccessibility; hepatocytes; mitochondrial membrane integrity; polyphenols; tea