title: Method development for determination of (+)-catechin and (-)-epicatechin by micellar electrokinetic chromatography: annual characterization of field grown blackberries.
abstract: Berries are a rich source of antioxidants compounds, among which is the catechin group. Determination of the monomers (catechin and epicatechin) in fruits is a first step in the way to establish a relationship between polyphenols and their effects on human health. The purpose of this work is to develop a method to determine free catechins in blackberry by MEKC and to characterize levels of catechins in fresh fruits of Rubus fruticosus var. Lochness throughout the annual production period. A methanolic extract was prepared from fresh fruit. Then, it was evaporated and the residue was extracted with diethyl ether. MEKC conditions: phosphoric acid, 30 mmol/L; SDS, 40 mmol/L and triethylamine, 0.1% v/v at pH 2.3; -15 kV of voltage; 10-s hydrodynamic injection; 25°C temperature; and detection at 200 nm. Instrumental and interday precision were lower than 4.7 and 10% RSD, respectively. Only (-)-epicatechin was quantified in blackberries and ranged from 120 to 620 mg/kg fresh weight, which were the lowest values in December and the highest in June. A solid-liquid extraction and an MEKC method were successfully applied to determine (-)-epicatechins in blackberry for the first time. A strong dependence of (-)-epicatechin on the annual average temperature was observed.
authors.affiliation: Department of Chemistry, Federal University of Santa Catarina, Florianópolis, SC, Brazil; Facultad de Farmacia, Universidad CEU San Pablo, Madrid, Spain.
authors.forename: Marcel
authors.initials: M
authors.lastname: Piovezan
authors.forename: Daniel
authors.initials: D
authors.lastname: García-Seco
authors.forename: Gustavo Amadeu
authors.initials: GA
authors.lastname: Micke
authors.forename: Javier
authors.initials: J
authors.lastname: Gutiérrez-Mañero
authors.forename: Beatriz
authors.initials: B
authors.lastname: Ramos-Solano
mesh_terms: D002392:Catechin / Q000032:analysis* / Q000302:isolation & purification; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D005638:Fruit / Q000737:chemistry*; D057230:Limit of Detection; D010936:Plant Extracts / Q000737:chemistry; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D013237:Stereoisomerism
chemical_list: D010936:Plant Extracts; D002392:Catechin
keywords: (−)-Epicatechin; Blackberry; Micellar electrokinetic chromatography; Rubus fruticosus; Solid-liquid extraction