title: HPLC-DAD Phenolic Characterization and Antioxidant Activities of Ripe and Unripe Sweet Orange Peels.
abstract: Phenolic compounds of unripe and ripe sweet orange peels were determined using a high-performance liquid chromatography separation method with diode array detector (HPLC-DAD). The in vitro antioxidant properties and the EC50 (concentration required to obtain a 50% antioxidant effect) values were also determined. The predominant phenolic compounds were quercitrin, rutin, and quercetin with values of 18.77 ± 0.01 mg/mL, 18.65 ± 0.03 mg/mL, and 10.39 ± 0.01 mg/mL respectively in unripe orange peel and 22.61 ± 0.01 mg/mL, 17.93 ± 0.03 mg/mL, and 14.03 ± 0.02 mg/mL respectively in ripe orange peel. The antioxidant properties revealed 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) diammonium salt (ABTS) scavenging ability of both unripe and ripe orange peels respectively as 14.68 ± 0.01 and 16.89 ± 0.02 mmol TEAC/g, the Ferric Reducing Antioxidant Properties (FRAP) as 70.69 ± 0.01 and 91.38 ± 0.01 mg gallic acid equivalents/100g, total phenol content as 5.27 ± 0.03 and 9.40 ± 0.01 mg gallic acid equivalents/g and total flavonoid content as 3.30 ± 0.30 and 4.20 ± 0.02 mg quercetin equivalent/g. The antioxidant assays showed enhanced potency of extract from ripe orange peel with EC50 values of 2.71 ± 0.03 mg/mL for 2,2-diphenyl-1-picrylhydrazyl (DPPH), 0.67 ± 0.03 mg/mL for hydroxyl radicals (OH*), 0.57 ± 0.02 mg/mL for Fe(2+) chelation, and 0.63 ± 0.06 mg/mL for malondialdehyde (MDA), and was more potent than unripe orange peel.
authors.affiliation: Department of Food Science and Technology, Federal University of Technology, P.M.B. 704, Akure 340284, Nigeria. omobasade@gmail.com.
authors.forename: Olufunmilayo Sade
authors.initials: OS
authors.lastname: Omoba
authors.affiliation: Department of Food Science and Technology, Federal University of Technology, P.M.B. 704, Akure 340284, Nigeria. ajufaye@gmail.com.
authors.forename: Rebeccah Olajumoke
authors.initials: RO
authors.lastname: Obafaye
authors.affiliation: Department of Biochemistry, Federal University of Technology, P.M.B. 704, Akure 340284, Nigeria. sosalawu@futa.edu.ng.
authors.forename: Sule Ola
authors.initials: SO
authors.lastname: Salawu
authors.affiliation: Phytochemical Research Laboratory, Department of Industrial Pharmacy, Federal University of Santa Maria, Build 26, Room 1115, Santa Maria, CEP 97105-900, Brazil. alinebolingon@yahoo.com.br.
authors.forename: Aline Augusti
authors.initials: AA
authors.lastname: Boligon
authors.affiliation: Phytochemical Research Laboratory, Department of Industrial Pharmacy, Federal University of Santa Maria, Build 26, Room 1115, Santa Maria, CEP 97105-900, Brazil. marga@ccs.ufsm.br.
authors.forename: Margareth Linde
authors.initials: ML
authors.lastname: Athayde
keywords: in vitro antioxidant; orange peel; phenolic profile