title: Antioxidant capacity of teas and herbal infusions: polarographic assessment.
abstract: Hydrogen peroxide scavenging (HPS) activity of unfermented (green, yellow, and white), partially fermented (oolong), and completely fermented (black) tea ( Camellia sinensis ), maté ( Ilex paraguariensis ), and various herbal infusions, as well as individual compounds (flavan-3-ols, flavonols, cinnamic and benzoic acids, and methylxanthines), was assessed by recently developed direct current (DC) polarographic assay. Correlations of tea and herbal infusion HPS activity with total phenolic content determined using the Folin-Ciocalteu assay (FC-GAE) (0.81 and 0.93), ferric reducing/antioxidant power (FRAP) (0.97 and 0.92), 1,1-diphenyl-2-picrylhydrazyl (DPPH) (0.77 and 0.80), and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) scavenging (0.86 and 0.86) were statistically significant. Correlations between relative antioxidant capacity index (RACI), calculated by assigning all applied assays equal weight, and HPS (0.98), FRAP (0.97), ABTS (0.89), and DPPH (0.89) confirmed DC polarographic assay reliability when applied individually. Correlation analysis, ANOVA, and Levene and Tukey's HSD tests unequivocally confirmed this reliable, rapid, and low-cost assay validity, clearly demonstrating its advantages over spectrophotometric assays applied.
authors.affiliation: Institute of General and Physical Chemistry , P.O. Box 45, 11 158 Belgrade 118, Serbia. stasago@yahoo.co.uk
authors.forename: Stanislava
authors.initials: S
authors.lastname: Gorjanović
authors.forename: Draženka
authors.initials: D
authors.lastname: Komes
authors.forename: Ferenc T
authors.initials: FT
authors.lastname: Pastor
authors.forename: Ana
authors.initials: A
authors.lastname: Belščak-Cvitanović
authors.forename: Lato
authors.initials: L
authors.lastname: Pezo
authors.forename: Ivana
authors.initials: I
authors.lastname: Hečimović
authors.forename: Desanka
authors.initials: D
authors.lastname: Sužnjević
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D019817:Benzoic Acid / Q000032:analysis; D052160:Benzothiazoles / Q000737:chemistry; D001628:Beverages / Q000032:analysis*; D001713:Biphenyl Compounds / Q000737:chemistry; D028241:Camellia sinensis / Q000737:chemistry; D002934:Cinnamates / Q000032:analysis; D044948:Flavonols / Q000032:analysis; D016166:Free Radical Scavengers / Q000032:analysis / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000032:analysis; D030019:Ilex paraguariensis / Q000737:chemistry; D010636:Phenols / Q000032:analysis; D010851:Picrates / Q000737:chemistry; D011048:Polarography / Q000379:methods*; D015203:Reproducibility of Results; D013451:Sulfonic Acids / Q000737:chemistry; D013662:Tea / Q000737:chemistry*; D014970:Xanthines / Q000032:analysis / Q000737:chemistry
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D002934:Cinnamates; D044948:Flavonols; D016166:Free Radical Scavengers; D010636:Phenols; D010851:Picrates; D013451:Sulfonic Acids; D013662:Tea; D014970:Xanthines; C029010:cinnamic acid; C008514:methylxanthine; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D019817:Benzoic Acid; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl