Resumo

Introduction: Natural products derived from plants play an important role in the prevention and treatment of diseases in humans. The heterogeneity and complexity of the molecular structures makes the employment of natural products for the treatment of infectious diseases a viable alternative to traditional antibiotic drug therapy, since there is less tendency of microbial resistance to phytomolecules. The hydroethanolic extracts from the stem bark of Anacardium occidentale L. (Cashew) have well-documented antimicrobial activity for microorganisms such as Escherichia coli, Candida and Streptococcus. However, the antibiofilm potential of this extract for Staphylococcus remains poorly explored. Objective: This study aimed to develop an antimicrobial product using liposomes technology for the encapsulation of flavonoids from A. occidentale stem bark hydroethanolic extract, with potential use for treating Staphylococal infections. Methods: 11 strains of S. aureus and 2 strains of S. epidermidis isolated from catheter tips and nasal cavities of patients on hemodialysis were used. The microorganisms were characterized considering the ability of biofilm formation by attached growth on 96 wells polystyrene microplates with and without supplementation of the culture medium, detection of icaA and icaD genes by PCR, and by congo red agar for carbohydrates production. Flavonoids were obtained by reverse phase chromatography on a C18 column, analyzed by TLC, HPLC and NMR, and MBC assays were performed. The flavonoids were entrapped in unilamellar liposomes produced by the film method. Results: The strains exhibited weak biofilm formation on polystyrene microplates, independently of supplementing the culture medium. Carbohydrates production was detected by congo red agar in most strains, except S. epidermidis and two S. aureus strains. icaA and icaD genes were detected in four S. aureus and two S. epidermidis. MBC assays indicated that free and liposome-loaded flavonoids were effective at 15 mg/ml. The liposomal formulation prepared with the MBC value was effective against the tested strains. Conclusion: The A. occidentale flavonoid liposomes can be a promising alternative for Staphylococal infections. In vivo studies are needed for developing a formulation for clinical use. Thanks to: FAPEMIG.