Potencial antimicrobiano e antioxidante de extratos de Hancornia speciosa frente a patógenos causadores de infecções cutâneas

Abstract

Infections caused by microorganisms pose a global challenge due to the increasing resistance to antimicrobials. The insufficient number of new therapeutic agents to address this issue characterizes what researchers refer to as the "post-antibiotic era." Pathogens such as Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa are frequently associated with hard-to-treat infections, especially skin infections, and may possess resistance mechanisms against antimicrobials considered first-choice therapies, resulting in high healthcare costs. In this context, researchers have been exploring plant extracts and essential oils as alternatives to conventional therapies. Hancornia speciosa, a tree native to Brazil, has been investigated for its therapeutic properties; however, few studies have assessed the antimicrobial effect of extracts from this plant prepared with different extraction solvents. This study aimed to develop extracts from the leaves and bark of H. speciosa and evaluate their antimicrobial activity against the microorganisms S. aureus, S. epidermidis, and P. aeruginosa, which are involved in dermatological infections. For this purpose, the extracts were produced using the Soxhlet serial exhaustive extraction method and cold maceration, followed by phenol and flavonoid quantification. Antioxidant activity was assessed using the DPPH radical assay. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests were performed, as well as disk diffusion assays to evaluate synergism with commercial antibiotics. Phenol quantification revealed that the hydroethanolic bark extract had the highest total phenol content, followed by the ethyl acetate and hexane extracts. Regarding flavonoids, the chloroform extract from leaves (3196.66±5.74 EQ/mg) and the hexane extract from leaves (1352.50±9.01 EQ/mg), both extracted by Soxhlet, showed the highest concentrations. In the antioxidant activity test with DPPH, the hydroalcoholic bark extract obtained through cold maceration showed the best result, with an IC50 of 6.46 μg/mL and AAI of 15.47. The extracts demonstrated antimicrobial activity both individually and synergistically with commercial antimicrobials, with particular highlights for the hexane bark extract obtained by Soxhlet and the hydroethanolic bark extract obtained through cold maceration, which had MIC values of 1.25 mg/mL and 5 mg/mL, respectively. Overall, the bark extracts of H. speciosa proved to be superior to the leaf extracts in terms of antimicrobial and antioxidant activities. This study is the first to compare H. speciosa extracts prepared using Soxhlet with different solvents, as well as to compare leaf and bark extracts obtained through cold ethanol extraction. The results suggest that H. speciosa has potential as a source of bioactive compounds with significant activity against clinical pathogens and antioxidant properties, making it a promising therapeutic alternative for dermatological infections.