title: Evaluation of functional stability of quercetin as a raw material and in different topical formulations by its antilipoperoxidative activity.
abstract: The present study evaluates the antioxidant activity of the flavonol quercetin, and its functional stability as a raw material and when added in formulations. The iron-chelating activity was determined using the bathophenanthroline assay, and the functional stability was evaluated with the antilipoperoxidative assay. Raw material presented concentration-dependent antilipoperoxidative and iron-chelating activities. The initial antilipoperoxidative activity of the raw material, cream and gel-cream were 63%, 78%, and 69%, respectively. There was no detectable loss of activity during 182 days (6 months) of storage at all tested temperatures (4°C, room temperature [RT], 37°C, and 45°C) for the raw material. Considering the method variability of 10%, activity loss greater than 10% for nonionic cream was detected after 126 days at 4°C (20.1%), decreasing thereafter to 22.2% after 182 days. At 45°C, the loss of activity started after 182 days (13.2%). For the anionic gel-cream, activity loss started after 84 days (28.4%, 45°C), decreasing after 182 days to 40.3% at 45°C. At 37°C, activity loss was detected after 182 days (12%). In conclusion, the results suggest that the activity of quercetin depends on iron chelation, and its posible usefulness as a topical antioxidant to prevent oxidative stress-induced skin damage depends on maintaining its antilipoperoxidative activity stored at RT, which avoids special storage conditions.
authors.affiliation: Department of Pharmaceutical Science, Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café s/n, CEP 14040-903, Ribeirão Preto, SP, Brazil. rubiacasa@yahoo.com.br.|Department of Food and Drugs Technology, Agricultural Sciences Center, Londrina State University, Paraná, Brazil. rubiacasa@yahoo.com.br.
authors.forename: Rúbia
authors.initials: R
authors.lastname: Casagrande
authors.affiliation: Department of Pharmaceutical Science, Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café s/n, CEP 14040-903, Ribeirão Preto, SP, Brazil.
authors.forename: Sandra R
authors.initials: SR
authors.lastname: Georgetti
authors.affiliation: Department of Pharmacology, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Waldiceu A
authors.initials: WA
authors.lastname: Verri
authors.affiliation: Department of Pharmaceutical Science, Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café s/n, CEP 14040-903, Ribeirão Preto, SP, Brazil.
authors.forename: José R
authors.initials: JR
authors.lastname: Jabor
authors.affiliation: Department of Clinical, Toxicological and Bromatological Analysis, Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Santos
authors.affiliation: Department of Pharmaceutical Science, Faculty of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café s/n, CEP 14040-903, Ribeirão Preto, SP, Brazil.
authors.forename: Maria J V
authors.initials: MJ
authors.lastname: Fonseca
keywords: antioxidant; flavonoids; lipid peroxidation; quercetin; stability