Quantification of antioxidant capacity of eyedrops and artificial tears based on the consumption of the MPPD*+free radical originated from the oxidation of n-(4-methoxyphenyl)-1,4-phenylenediamine

• Grant number: 18/26114-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2019
• End date: February 29, 2020
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Horacio Dorigan Moya
• Grantee: Cinthia dos Santos
• Host Institution: Centro Universitário Saúde ABC. Fundação do ABC. Santo André , SP, Brazil

Abstract

The aim of this project is the development of a spectrophotometric method for the quantification of the total antioxidant capacity of ophthalmic formulations based on the consumption of the MPPD*+ free radical (purple) which is originated from the oxidation of N-(4-methoxyphenyl)-1,4-phenylenediamine (MPPD, blue). Previous results revealed that the addition of eye drops in a solution containing MPPD * + promoted a decrease in absorbance values at 569 nm, allowing the determination of the total antioxidant capacity of these samples. Once the best methodological conditions have been established, the proposed reaction will be used to quantify the total antioxidant capacity of eye drops after a certain opening time of the package. With this study it will be possible to evaluate if the antioxidant capacity is affected by this procedure and to bring information about the so-called shelf life of these products. After this, the proposed method will be used to quantify the antioxidant capacity in samples of artificial tears made from the mixture of antioxidant compounds and may be applied in tears of patients undergoing therapeutic treatments. For comparison purposes, the antioxidant capacity values of the same samples will be measured using the spectrophotometric method based on the reduction of Fe(III)/2,4,6-tripyridyl-s-triazine complexes which is expensive and still was not used to establish a possible relationship between the CAT values of artificial drops or tears and their composition. This, in addition to the information described above, encourages the development of a simple, reproducible, easy-to-execute, and cost-effective method.