Avaliação da aplicação de extratos de chá branco (Camellia sinensis) e calêndula (Calendula officinalis) no preparo de gaze antimicrobiana

Abstract

Many compounds commonly found in plants and fruits have antioxidant and antimicrobial activities recognized. These bioactive compounds have broad potential for application for human and animal health and in the food, pharmaceutical, cosmetic industries. Calendula extracts have been used in Europe for many years as topical anti-inflammatory agents. In addition, several studies have demonstrated the antimicrobial activity of marigold against fungi and pathogenic bacteria. White tea is consumed worldwide and its extracts have antioxidant and antimicrobial activity. In this context, the objective of this work was to prepare the aqueous and hydroalcoholic extracts of samples of white tea and dry calendula flowers, for later evaluation of their antioxidant and antimicrobial action. The analyzes were carried out in vitro in relation to the quantification of the total phenolic compounds by the Folin-Ciocalteau method, with posterior evaluation of the antioxidant activity by the DPPH test; and regarding the antimicrobial activity, the tests were carried out by using the broth microdilution method for the determination of minimum inhibitory concentration and minimal bactericidal concentration, with Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538. The results revealed that both extracts analyzed had a considerable content of phenolic compounds. However, the extracts of white tea presented the highest amount of these compounds, with respectively 6.45 and 6.28 mg EAG / g of the sample; nevertheless, a relationship between the amount of phenolic compounds and antioxidant activity was not determined, once it was the hydroalcoholic extract of marigold that presented the highest antioxidant activity by the tested method (57.67 μmol ET / L). In addition, the antimicrobial properties of the hydroalcoholic extracts were proven, thus evidencing the potential for application of these extracts in the preparation of cotton gels with antimicrobial activity. Samples of cotton gauze (15x15 cm) were prepared by immersing it in the extracts for variable times (between 15 minutes and 1 hour) in different temperature conditions (room and refrigerator). After the immersion and drying of the gauzes, the determination of the antibacterial activity of the gauze was carried out based on the AATCC method 100: 2004. The results obtained for the antimicrobial gauze were satisfactory against the hydroalcoholic extract of marigold, which has obtained percentages of bacterial reduction of 99% and 100% for S. aureus and E. coli respectively; not with standing, more studies are still needed in order to improve this innovative application.