Effects of green tea polyphenols against metal-induced genotoxic damage: underlying mechanistic pathways.

This review is based upon evidence from the published effects of green tea polyphenols (GTP) on genotoxic damage induced by metals with carcinogenic potential. First, the relationship between GTP and antioxidant defense system is provided. Subsequently, the processes involved in the oxidative stress generated by metals and their relationship to oxidative DNA damage is examined. The review demonstrated that GTP generally decrease oxidative DNA damage induced by exposure to metals such as arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), chromium (Cr), iron (Fe), and lead (Pb). The pathways involved in these effects are related to: (1) direct scavenging of free radicals (FR); (2) activation of mechanisms to repair oxidative DNA damage; (3) regulation of the endogenous antioxidant system; and (4) elimination of cells with genetic damage via apoptosis. The results obtained in the studies reviewed demonstrate potential for possible use of GTP to prevent and treat oxidative damage in populations exposed to metals. Further, GTP may be considered as adjuvants to treatments for metal-associated diseases related to oxidative stress and DNA damage.

Catequinas del té verde: efectos antigenotóxicos y genotóxicos. Revisión sistemática / Green tea catechins: antigenotoxic and genotoxic effects. Systematic review

Las catequinas del té verde (Camellia sinensis) (CTV) presentan efectos benéficos para la salud asociados a su potencial antioxidante. Por otra parte, el estrés oxidante es una de las vías de inducción de daño genotóxico. De ahí que, en la presente revisión se realizó un análisis de los efectos antigenotóxicos y genotóxicos de las CTV, haciendo énfasis en las vías implicadas en estos procesos y sus efectos en la salud. Se realizó una revisión de artículos indexados en las bases de datos de PubMed® y Science Direct® (2021) con las palabras clave "green tea" y "green tea catechins". Se delimitaron los estudios utilizando los operadores booleanos "AND", "OR" y "NOT" ("antigenotoxic", "genotoxic", "antioxidant" y "prooxidant"). En su mayoría se consideraron las publicaciones del 2016 al 2021. Se observó que los efectos benéficos en la salud de las CTV están relacionados con: a) su actividad antioxidante mediante la captura, inhibición y prevención de la formación de las especies reactivas de oxígeno; b) la regulación del sistema antioxidante endógeno; c) la activación de los mecanismos de reparación al contribuir en la eliminación del aducto 8-hidroxi-2'-desoxiguanosina; d) la inducción de apoptosis en células con daño al ADN; y e) la inhibición de la inflamación relacionada con su actividad antiapoptótica. Si bien, en algunos de los estudios se reportaron efectos genotóxicos, estos a su vez contribuyeron en la eliminación de células con daño genético, por lo que, no se puede considerar del todo a la actividad genotóxica de las CTV como perjudiciales para la salud(AU)

The green tea catechins (Camellia sinensis) (CTV) have beneficial effects for health associated with their antioxidant potential. Moreover, oxidative stress is one of the pathways for inducing genotoxic damage. Hence, in this review, an analysis of the antigenotoxic and genotoxic effects of CTV was carried out, emphasizing the pathways involved in these processes and their effects on health. A review of articles indexed in the PubMed® and ScienceDirect® (2021) databases with the keywords "green tea" and "green tea catechins" was carried out. Studies were delimited using the Boolean operators "AND", "OR" and "NOT" ("antigenotoxic", "genotoxic", "antioxidant" and "prooxidant"). For the most part, publications from 2016 to 2021 were considered. It was observed that the beneficial health effects of CTVs are related to: a) their antioxidant activity through the capture, inhibition and prevention of the formation of reactive oxygen species; b) the regulation of the endogenous antioxidant system; c) the activation of the repair mechanisms by contributing to the elimination of the 8-hydroxy-2'-deoxyguanosine adduct; d) the induction of apoptosis in cells with DNA damage; and e) the inhibition of inflammation related to its antiapoptotic activity. Although some of the studies reported genotoxic effects, these in turn contributed to the elimination of cells with genetic damage. Therefore, the genotoxic activity of CTV cannot be considered as harmful to health

Antigenotoxic and apoptotic activity of green tea polyphenol extracts on hexavalent chromium-induced DNA damage in peripheral blood of CD-1 mice: analysis with differential acridine orange/ethidium bromide staining.

This study was conducted to investigate the modulating effects of green tea polyphenols on genotoxic damage and apoptotic activity induced by hexavalent chromium [Cr (VI)] in CD-1 mice. Animals were divided into the following groups: (i) injected with vehicle; (ii) treated with green tea polyphenols (30 mg/kg) via gavage; (iii) injected with CrO3 (20 mg/kg) intraperitoneally; (iv) treated with green tea polyphenols in addition to CrO3. Genotoxic damage was evaluated by examining micronucleated polychromatic erythrocytes (MN-PCEs) obtained from peripheral blood at 0, 24, 48, and 72 h after treatment. Induction of apoptosis and cell viability were assessed by differential acridine orange/ethidium bromide (AO/EB) staining. Treatment of green tea polyphenols led to no significant changes in the MN-PCEs. However, CrO3 treatment significantly increased MN-PCEs at 24 and 48 h after injection. Green tea polyphenols treatment prior to CrO3 injection led to a decrease in MN-PCEs compared to the group treated with CrO3 only. The average of apoptotic cells was increased at 48 h after treatment compared to control mice, suggesting that apoptosis could contribute to eliminate the DNA damaged cells induced by Cr (VI). Our findings support the proposed protective effects of green tea polyphenols against the genotoxic damage induced by Cr (VI).