title: Quantification of individual phenolic compounds' contribution to antioxidant capacity in apple: a novel analytical tool based on liquid chromatography with diode array, electrochemical, and charged aerosol detection.
abstract: Phenolics, particularly from apples, hold great interest because of their antioxidant properties. In the present study, the total antioxidant capacity of different apple extracts obtained by pressurized hot water extraction (PHWE) was determined by cyclic voltammetry (CV), which was compared with the conventional antioxidant assays. To measure the antioxidant capacity of individual antioxidants present in apple extracts, a novel method was developed based on high-performance liquid chromatography (HPLC) with photodiode array (DAD), electrochemical (ECD), and charged aerosol (CAD) detection. HPLC-DAD-ECD-CAD enabled rapid, qualitative, and quantitative determination of antioxidants in the apple extracts. The main advantage of using CAD was that this detector enabled quantification of a large number of phenolics using only a few standards. The results showed that phenolic acids and flavonols were mainly responsible for the total antioxidant capacity of apple extracts. In addition, protocatechuic acid, chlorogenic acid, hyperoside, an unidentified phenolic acid, and a quercetin derivative presented the highest antioxidant capacities.
authors.affiliation: Department of Chemistry, Centre for Analysis and Synthesis, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Merichel
authors.initials: M
authors.lastname: Plaza
authors.forename: James
authors.initials: J
authors.lastname: Kariuki
authors.forename: Charlotta
authors.initials: C
authors.lastname: Turner
mesh_terms: D000336:Aerosols; D000975:Antioxidants / Q000032:analysis*; D002726:Chlorogenic Acid / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D055664:Electrochemical Techniques; D005638:Fruit / Q000737:chemistry*; D062385:Hydroxybenzoates / Q000032:analysis; D027845:Malus / Q000737:chemistry*; D010636:Phenols / Q000032:analysis*; D010936:Plant Extracts / Q000737:chemistry; D011794:Quercetin / Q000031:analogs & derivatives / Q000032:analysis; D013045:Species Specificity
chemical_list: D000336:Aerosols; D000975:Antioxidants; D062385:Hydroxybenzoates; D010636:Phenols; D010936:Plant Extracts; D002726:Chlorogenic Acid; C009091:protocatechuic acid; C021304:hyperoside; D011794:Quercetin; C017616:phenolic acid
keywords: antioxidant capacity; charged aerosol detector; cyclic voltammetry; electrochemical detector; hyphenation; phenolic compounds