Composição química e atividade antibacteriana dos óleos essenciais de Croton urticifolius LAM. e Croton adamantinus MÜLL. ARG. (EUPHORBIACEAE)

Abstract

The genus Croton, one of the largest in the Euphorbiaceae family, has aromatic species that produce essential oils that are characterized by their biological activities: anti-inflammatory, antioxidant, antimicrobial, cytotoxic, among others. The objective of this work was to investigate the chemical composition and antibacterial activity of the essential oils of the leaves from Croton urticifolius (OCU) and Croton adamantinus (OCA) collected in the municipality from Areia - PB. The essential oils from the fresh leaves of the Croton species were extracted by hydrodistillation in a Clevenger type apparatus and analyzed by gas chromatography coupled with mass spectrometry (GC/MS) to identify the chemical composition. The analysis by GC/MS allowed the identification of 22 compounds (95.0%), with the majority being sesquiterpenoids. The main compounds for C. urticifolius oil were α pinene (21.70%), bicyclogermacrene (21.46%) and (E) -cariophylene (17.34%), and from C. adamantinus oil were bicyclogermacrene (36.47%), γ-amorphene (22.91%) and (E) - cariophylene (9.22%). The antibacterial activity of the oils was tested against the strains Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 8739), using the Minimum Inhibitory Concentration (MIC) method in 96-well plates (microdilution). OCU showed weak activity against E. coli, with MIC of 512 μg.mL-1 . While the OCA showed no activity against any tested strain. The modulating effect of the oils was evaluated against the resistant S. aureus multidroga strain (UFPEDA 802) and the results obtained demonstrate that the association for OCU and OCA with the antibiotic Ciprofloxacino is positive, since it leads to the potentiation of the antibiotic effect. It is necessary to obtain more concrete data for the safe use of these combinations, paying attention to the existence of some type of existing toxicity reaction related to the herbal medicine and to understand the resistance mechanisms acquired by the microorganism.