Avaliação da atividade antimicrobiana e antioxidante a partir do extrato seco de Anacardium occidentale Lineu padronizado em taninos totais

Abstract

Introduction: Anacardium occidentale is a plant belonging to the Anacardiaceae family, commonly known as “cajuzinho-do-cerrado” or “caju-do-campo”, and is widely found in the Brazilian Cerrado biome. The secondary metabolism of the leaves, bark, and pseudofruit of this species results in the production of phenolic compounds, such as flavonoids, tannins, and anacardic acid. These metabolites, characteristic of species of the genus Anacardium, exhibit several biological properties, including antitumor activity, preventive effects against cardiovascular diseases, as well as anti-inflammatory and antimicrobial activities. Objective: To obtain the dry extract of Anacardium occidentale standardized in total tannins, as well as to evaluate its antimicrobial and antioxidant activities. Methodology: Initially, the plant material was characterized, followed by the preparation of soft extracts standardized in total tannins from the leaves of Anacardium occidentale. The optimization study was conducted using a BoxBehnken experimental design, evaluating the following factors: ultrasound extraction time 10, 20, and 30 minutes, solid-to-liquid ratio 4, 8, and 12 g/mL, extraction temperature 25, 35, and 40 ºC, and ethanol concentration (EtOH, m/m%) fixed at 96%. The antioxidant activity of the extracts was determined using DPPH and ABTS⁺ radical scavenging assays. Antimicrobial activity was evaluated using the dry extract against reference microorganisms from the American Type Culture Collection (ATCC): Cryptococcus gattii ATCC 24065, Cryptococcus neoformans ATCC 28957 and ATCC 90112, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 27853, Salmonella sp. ATCC 14028, and Staphylococcus aureus ATCC 29213, using the broth microdilution method in 96-well plates. Results and Discussion: In the optimization of total tannin extraction, the solid-to-solvent ratio was identified as the most influential variable. Regarding antimicrobial activity, the dry extract of Anacardium occidentale demonstrated effectiveness against microorganisms of the genera Cryptococcus and Candida. Conclusions: The dry extract of Anacardium occidentale showed significant antioxidant activity (IC₅₀ = 2.79 µg/mL) and antimicrobial activity against Escherichia coli and Staphylococcus aureus, exhibiting superior responses compared to the other concentrations evaluated in this study.