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Quenching of alpha,beta-unsaturated aldehydes by green tea polyphenols: HPLC-ESI-MS/MS studies.
J Pharm Biomed Anal. 2008 Nov 04; 48(3):606-11.JP

Abstract

The aim of this work was to investigate in vitro the quenching activity of green tea polyphenols against alpha,beta-unsaturated aldehyde, using 4-hydroxy-nonenal (HNE) as prototype and HPLC-ESI-MS/MS techniques. HNE is the most abundant and genotoxic product of oxidation of dietary polyunsaturated fatty acids, and is believed to be involved in the early stage of colorectal carcinogenesis on account of its genotoxic potential. Both epigallocatechin gallate (EGCG, 1.0-3.5mM), the main constituent of green tea polyphenols, and a green tea aqueous extract are able to quench HNE (50 microM) in colorectal physiomimetic conditions (10mM phosphate buffer, pH 8.0, 37 degrees C), giving rise to the formation of six diastereomeric covalent adducts at the ring A of EGCG, as indicated by their ESI-MS/MS fragmentation pathways. The specificity of the adduction positions was explained by (1)H NMR experiments. HNE quenching is pH-dependent and maximum at pH 8.0. ESI-MS analysis showed no formation of 4-hydroxy-2,3-epoxy-nonanal, or adduction of the epoxide to EGCG. This implies that too little hydrogen peroxide (1mM, 24h incubation, FOX-2 method) develops from auto-oxidation of EGCG in our aerobic experimental conditions to oxidize HNE to its corresponding epoxide, so this mechanism is not responsible for the compound's disappearance. EGCG and green tea extract also quenched acrolein, another genotoxic alpha,beta-unsaturated aldehyde, giving one predominant adduct and minor isobaric species, probably due the adduction of acrolein at different positions of the EGCG ring A. These results suggest that EGCG and green tea extract, beside the proposed mechanisms of chemoprevention that target multiple cell-signaling pathways that control cell proliferation and apoptosis in cancer cells, can also prevent protein carbonylation in the tumor tissue environment, depending on the pH of the medium surrounding the tissue, the type of tumor, the stage of dysregulation of lipid peroxidation and, finally, the stage of carcinoma development.

Authors+Show Affiliations

Istituto di Chimica Farmaceutica e Tossicologica "Pietro Pratesi", Faculty of Pharmacy, University of Milan, via Mangiagalli 25, 20131 Milan, Italy. giangiacomo.beretta@unimi.itNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18619756

Citation

Beretta, Giangiacomo, et al. "Quenching of Alpha,beta-unsaturated Aldehydes By Green Tea Polyphenols: HPLC-ESI-MS/MS Studies." Journal of Pharmaceutical and Biomedical Analysis, vol. 48, no. 3, 2008, pp. 606-11.
Beretta G, Furlanetto S, Regazzoni L, et al. Quenching of alpha,beta-unsaturated aldehydes by green tea polyphenols: HPLC-ESI-MS/MS studies. J Pharm Biomed Anal. 2008;48(3):606-11.
Beretta, G., Furlanetto, S., Regazzoni, L., Zarrella, M., & Facino, R. M. (2008). Quenching of alpha,beta-unsaturated aldehydes by green tea polyphenols: HPLC-ESI-MS/MS studies. Journal of Pharmaceutical and Biomedical Analysis, 48(3), 606-11. https://doi.org/10.1016/j.jpba.2008.05.036
Beretta G, et al. Quenching of Alpha,beta-unsaturated Aldehydes By Green Tea Polyphenols: HPLC-ESI-MS/MS Studies. J Pharm Biomed Anal. 2008 Nov 4;48(3):606-11. PubMed PMID: 18619756.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Quenching of alpha,beta-unsaturated aldehydes by green tea polyphenols: HPLC-ESI-MS/MS studies. AU - Beretta,Giangiacomo, AU - Furlanetto,Sandra, AU - Regazzoni,Luca, AU - Zarrella,Marina, AU - Facino,Roberto Maffei, Y1 - 2008/06/05/ PY - 2008/04/10/received PY - 2008/05/28/revised PY - 2008/05/29/accepted PY - 2008/7/16/pubmed PY - 2009/2/27/medline PY - 2008/7/16/entrez SP - 606 EP - 11 JF - Journal of pharmaceutical and biomedical analysis JO - J Pharm Biomed Anal VL - 48 IS - 3 N2 - The aim of this work was to investigate in vitro the quenching activity of green tea polyphenols against alpha,beta-unsaturated aldehyde, using 4-hydroxy-nonenal (HNE) as prototype and HPLC-ESI-MS/MS techniques. HNE is the most abundant and genotoxic product of oxidation of dietary polyunsaturated fatty acids, and is believed to be involved in the early stage of colorectal carcinogenesis on account of its genotoxic potential. Both epigallocatechin gallate (EGCG, 1.0-3.5mM), the main constituent of green tea polyphenols, and a green tea aqueous extract are able to quench HNE (50 microM) in colorectal physiomimetic conditions (10mM phosphate buffer, pH 8.0, 37 degrees C), giving rise to the formation of six diastereomeric covalent adducts at the ring A of EGCG, as indicated by their ESI-MS/MS fragmentation pathways. The specificity of the adduction positions was explained by (1)H NMR experiments. HNE quenching is pH-dependent and maximum at pH 8.0. ESI-MS analysis showed no formation of 4-hydroxy-2,3-epoxy-nonanal, or adduction of the epoxide to EGCG. This implies that too little hydrogen peroxide (1mM, 24h incubation, FOX-2 method) develops from auto-oxidation of EGCG in our aerobic experimental conditions to oxidize HNE to its corresponding epoxide, so this mechanism is not responsible for the compound's disappearance. EGCG and green tea extract also quenched acrolein, another genotoxic alpha,beta-unsaturated aldehyde, giving one predominant adduct and minor isobaric species, probably due the adduction of acrolein at different positions of the EGCG ring A. These results suggest that EGCG and green tea extract, beside the proposed mechanisms of chemoprevention that target multiple cell-signaling pathways that control cell proliferation and apoptosis in cancer cells, can also prevent protein carbonylation in the tumor tissue environment, depending on the pH of the medium surrounding the tissue, the type of tumor, the stage of dysregulation of lipid peroxidation and, finally, the stage of carcinoma development. SN - 0731-7085 UR - https://www.unboundmedicine.com/medline/citation/18619756/Quenching_of_alphabeta_unsaturated_aldehydes_by_green_tea_polyphenols:_HPLC_ESI_MS/MS_studies_ DB - PRIME DP - Unbound Medicine ER -