New spectrophotometric method for quantification of the antioxidant capacity of tropical fruits and medicinal plant extracts based on the formation of Fe(II)/1,10-phenanthroline complexes

• Grant number: 17/12714-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2017
• End date: July 31, 2018
• Field of knowledge: Health Sciences - Pharmacy - Food Science
• Principal Investigator: Horacio Dorigan Moya
• Grantee: Aline Freire Gouveia de Amorim
• Host Institution: Faculdade de Medicina do ABC (FMABC). Organização Social de Saúde. Fundação do ABC. Santo André , SP, Brazil

Abstract

The aim of this project is the development of an alternative spectrophotometric method to quantify the antioxidant capacity of some Brazilian tropical fruits and medicinal plant extracts based on the reduction reaction of Fe(III) to Fe(II) in aqueous solution containing excess of 1, 10-phenanthroline (1,10-phen).Fruits and plant extracts are rich in antioxidant compounds and the addition of aliquots of these samples in a solution containing Fe(III) and 1,10-phen (pH 4.6; acetate buffer) form the orange [Fe(phen)3]2+ complex. As a calculation methodology, the absorbance values of the[Fe(phen)3]2+ complex will be compared with the absorbance values of an ascorbic acid solution (standard antioxidant) obtained under the same experimental conditions and then used to express the antioxidant capacity of these samples. In the last step of this project the individual reducing capacity of various phenolic acids (eg gallic acid) and flavonoids (eg quercetin) will be determined using the same reaction as the proposed method. This study with standard antioxidant solutions will elucidate how the type of chemical structure and the radicals attached to the benzene group (and possibly the molar mass of the compound) change the value of the reducing capacity of each polyphenolic compound with the reaction used. In addition, the influence of the number and position of the hydroxyl groups present on each polyphenol will also be investigated, since the presence of these groups is known to be strongly responsible for the antioxidant capacity of the polyphenolic compounds. (AU)