title: Evaluation of the antioxidant activity and capacity of some natural N6-substituted adenine derivatives (cytokinins) by fluorimetric and spectrophotometric assays.
abstract: Four natural N(6)-substituted adenine derivatives (cytokinins) were evaluated for the first time in vitro for they antioxidant capacity by using fluorimetric and spectrophotometric assays, i.e., the oxygen radical absorbance capacity (ORAC), trolox equivalence antioxidant capacity (TEAC) and the 2-deoxyribose degradation (2-DRA) assays. The results from the TEAC assay show that only N(6)-(4-hydroxybenzyl)adenine (p-topolin) shows an electron transfer capacity due to the presence of a phenolic moiety in the N(6)-position. The results from the ORAC test show that the antioxidant activity of N(6)-furfuryladenine (kinetin, K) is the highest up to a concentration of 1 μM, whereas at concentrations higher than 1 μM p-topolin is the most efficient antioxidant. Analysis of the kinetic data suggests that, compared to the other cytokinins, more sites of the molecular structure of p-topolin are available for the quenching of peroxyl radicals. The hydroxyl radical scavenger ability, as measured by the 2-DRA assay, showed that all tested cytokinins react in this test and that N(6)-(Δ(2)-isopentenyl)adenine is slightly more potent, probably because of the allylic methylene group present in the N(6)-isopentenyl moiety. Our data suggest that a part of the biological activity of the evaluated cytokinins is likely to be related to an intrinsic antioxidant capacity.
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via Di Rudinì 8, 20142 Milan, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Brizzolari
authors.affiliation: Department of Pharmaceutical Sciences, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Marinello
authors.affiliation: Department of Pharmaceutical Sciences, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Carini
authors.affiliation: Department of Health Sciences, Università degli Studi di Milano, Via Di Rudinì 8, 20142 Milan, Italy.
authors.forename: Enzo
authors.initials: E
authors.lastname: Santaniello
authors.affiliation: Department of Veterinary Science and Public Health, Università degli Studi di Milano, Via Celoria 10, 20133 Milan, Italy. Electronic address: pierantonio.biondi@unimi.it.
authors.forename: Pier Antonio
authors.initials: PA
authors.lastname: Biondi
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D003583:Cytokinins / Q000737:chemistry*; D005470:Fluorometry / Q000379:methods*; D007700:Kinetics; D015394:Molecular Structure; D013053:Spectrophotometry / Q000379:methods*
chemical_list: D000975:Antioxidants; D003583:Cytokinins
keywords: 2-Deoxyribose degradation assay; Antioxidant activity; Cytokinins; Oxygen radical absorbance capacity (ORAC); Trolox equivalent antioxidant capacity (TEAC)