Atividade antimicrobiana do óleo essencial de Croton pluriglandulosus Carn. (Euphorbiaceae) contra microrganismos de interesse clínico

Abstract

Fungal and bacterial infections remain significant causes of morbidity and mortality, exacerbated by increasing resistance to conventional antimicrobials. Yeasts of the genus Candida cause infections in both immunocompetent and immunocompromised individuals, while associated pathogenic bacteria are the primary cause of urinary, respiratory, and systemic infections, often resistant to multiple classes of antimicrobials. In this context, plant-derived essential oils stand out as promising therapeutic alternatives due to their antifungal and antibacterial properties. Their antimicrobial activity is mainly related to the destabilization of the plasma membrane and interference in essential metabolic processes, contributing to the fight against microbial resistance. This study aims to evaluate the antimicrobial activity and mechanisms of action of the essential oil (EO) extracted from the leaves of Croton pluriglandulosus Carn.-Torres & Riina (CpEO) on human pathogenic microorganisms in planktonic lifestyles and biofilms. The results demonstrated that the essential oil of Croton pluriglandulosus has 26 different metabolites, with elemicin (25.77%), bicyclogermacrene (9.37%), caryophyllene (8.99%), 1,3,5-trimethoxybenzene (6.86%), and hedicariol (6.21%) being the major compounds. The oil, at a concentration of 50 μg mL−1 , was able to inhibit the planktonic growth of C. krusei (89.3%) and C. parapsilosis (80.70%). Furthermore, biofilm formation was initiated in 85.5% of C. krusei and 77.9% of C. parapsilosis. There was no reduction in the biomass of the pre-formed biofilm. The prevention data were not excessive for the species C. albicans and all tested bacterial species (B. subtilis, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus e Salmonella enterica). Fluorescence microscopy analyses showed that the oil ages, causing cell membrane damage, cell death, and inducing the production of reactive oxygen species (ROS). Electron microscopy images showed high-resolution morphological damage to the cells upon contact with the oil. Furthermore, the oil did not cause hemolysis in human erythrocytes at the concentrated level. The data obtained offer a future alternative for obtaining drugs and active compounds to be used by the clinical sector for microbiological control purposes.