{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,24]],"date-time":"2026-10-24T00:32:39Z","timestamp":1792801959398,"version":"4.5.0"},"reference-count":50,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,5,27]],"date-time":"2022-05-27T00:00:00Z","timestamp":1653609600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Medical University Lodz","award":["503\/1-079-01\/503-11-001"],"award-info":[{"award-number":["503\/1-079-01\/503-11-001"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Hydroxyl radical (\u2022OH) scavenging and the regeneration of Fe2+ may inhibit or enhance peroxidative damage induced by a Fenton system, respectively. Plant polyphenols reveal the afore-mentioned activities, and their cumulative net effect may determine anti- or pro-oxidant actions. We investigated the influence of 17 phenolics on ultra-weak photon emission (UPE) from a modified Fenton system (92.6 \u00b5mol\/L Fe2+, 185.2 \u00b5mol\/L EGTA (ethylene glycol-bis(\u03b2-aminoethyl-ether)-N,N,N\u2032,N,-tetraacetic acid) and 2.6 mmol\/L H2O2 pH = 7.4). A total of 8 compounds inhibited (antioxidant effect), and 5 enhanced (pro-oxidant effect) UPE at all studied concentrations (5 to 50 \u00b5mol\/L). A total of 4 compounds altered their activity from pro- to antioxidant (or vice versa) along with increasing concentrations. A total of 3 the most active of those (ferulic acid, chlorogenic acid and cyanidin 3-O-glucoside; mean UPE enhancement by 63%, 5% and 445% at 5 \u00b5mol\/L; mean UPE inhibition by 28%, 94% and 24% at 50 \u00b5mol\/L, respectively) contained catechol or methoxyphenol structures that are associated with effective \u2022OH scavenging and Fe2+ regeneration. Most likely, these structures can determine the bidirectional, concentration-dependent activity of some phenolics under stable in vitro conditions. This is because the concentrations of the studied compounds are close to those occurring in human fluids, and this phenomenon should be considered in the case of dietary supplementation with isolated phenolics.<\/jats:p>","DOI":"10.3390\/molecules27113453","type":"journal-article","created":{"date-parts":[[2022,5,29]],"date-time":"2022-05-29T23:43:03Z","timestamp":1653867783000},"page":"3453","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":79,"title":["Concentration Dependence of Anti- and Pro-Oxidant Activity of Polyphenols as Evaluated with a Light-Emitting Fe2+-Egta-H2O2 System"],"prefix":"10.3390","volume":"27","author":[{"given":"Michal","family":"Nowak","sequence":"first","affiliation":[{"name":"Radiation Protection, University Hospital No. 2, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wieslaw","family":"Tryniszewski","sequence":"additional","affiliation":[{"name":"Department of Radiological and Isotopic Diagnostics and Therapy, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Agata","family":"Sarniak","sequence":"additional","affiliation":[{"name":"Department of Clinical Physiology, Medical University of Lodz, Mazowiecka 6\/8, 92-215 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"Wlodarczyk","sequence":"additional","affiliation":[{"name":"Department of Sleep Medicine and Metabolic Disorders, Medical University of Lodz, Mazowiecka 6\/8, 92-215 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8876-0682","authenticated-orcid":false,"given":"Piotr J.","family":"Nowak","sequence":"additional","affiliation":[{"name":"Department of Nephrology, Hypertension, and Kidney Transplantation, Medical University of Lodz, Pomorska 251, 92-213 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3445-6930","authenticated-orcid":false,"given":"Dariusz","family":"Nowak","sequence":"additional","affiliation":[{"name":"Department of Clinical Physiology, Medical University of Lodz, Mazowiecka 6\/8, 92-215 Lodz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"384S","DOI":"10.3945\/an.112.003517","article-title":"Health-promoting components of fruits and vegetables in the diet","volume":"4","author":"Liu","year":"2013","journal-title":"Adv. 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