Abstract
Herbal medicines can be promising for the treatment of infections caused by multidrug-resistant microorganisms. This study aimed to evaluate Rosmarinus officinalis (Rosemary) hydroalcoholic extract (RHE) regarding its phytochemical composition and potential for eliminating polymicrobial biofilm of Candida albicans with multidrug-resistant bacteria (Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa). The extraction and quantification of the extract (flavonoids and phenols) were performed, and its antioxidant activity (DPPH) and the presence of bio-active compounds were investigated using high-performance liquid chromatography with Diode Array Detection (HPLC-DAD) and Gas Chromatography-Mass Spectrometry (GC-MS). The minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) were determined, and the extract's action on polymicrobial biofilms was evaluated using the MTT assay. Data were analyzed using one-way ANOVA and Tukey's tests, as well as Kruskal-Wallis and Dunn's tests, with a significance level of 5%. RHE showed compatible amounts of flavonoids and phenols, with an EC50 of 19.53 µg/mL. Through HPLC-DAD and GC-MS, biomolecules such as rosmarinic acid and α-Pinene were identified. The extract exhibited microbicidal activity and antibiofilm action, with reduction percentages of up to 69.6% (p < 0.05), showing superior performance compared to 0.12% chlorhexidine against C. albicans + A. baumannii. In conclusion, RHE may be a promising therapeutic agent against multidrug-resistant pathogens.