Synergistic and Antibiofilm Effects of the Essential Oil from Croton conduplicatus (Euphorbiaceae) against Methicillin-Resistant Staphylococcus aureus

Abstract

Bacterial resistance refers to the ability of bacteria to resist the action of some antibiotics due to the development of adaptation and resistance mechanisms. It is a serious public health problem, especially for diseases caused by opportunistic bacteria. In this context, the search for new drugs, used alone or in combination, appears as an alternative for the treatment of microbial infections, and natural products, such as essential oils, are important in this process due to their structural diversity, which increases the probability for antimicrobial action. The objective of this study was to extract and identify the chemical components of the essential oil from Croton conduplicatus (EOCC), to evaluate the antimicrobial activity, to investigate the effect of the interaction between the EOCC and different antibiotics and to evaluate its antibiofilm potential. The EOCC was obtained by hydrodistillation. Based on chemical characterisation, 70 compounds were identified, with 1.8 cineole (13.15%), p-cymene (10.68%), caryophyllene (9.73%) and spathulenol (6.36%) being the major constituents. The minimum inhibitory concentration (MIC) values of EOCC were 256 and 512 µg mL−1 for methicillin-sensitive and -resistant Staphylococcus aureus strains (MSSA and MRSA), respectively. The combinations of EOCC with the antibiotics oxacillin and ampicillin were synergistic (OXA/EOCC and AMP/EOCC combined decreased the OXA MIC and AMP MIC to 0.5 and 0.25 for MSSA, respectively, and OXA/EOCC and AMP/EOCC combined decreased the OXA MIC and the AMP MIC to 1 and 0.5 for MRSA, respectively) and could modify the resistance profile of MSSA and MRSA strains. The results indicated that EOCC was also able to partially inhibit biofilm formation. Our study presents important information about the chemical composition of EOCC and its antimicrobial potential and provides a reference to determine the mechanisms of action of EOCC and its use in pharmaceutical formulations.

Staphylococcus aureus biofilm: Formulation, regulatory, and emerging natural products-derived therapeutics

“…EOs, volatile compounds extracted from medicinal plants, have shown great therapeutic potential against microbial biofilms [ [102] , [103] , [104] , [105] ]. The EOs extracted from Croton species (e.g., C. blanchetianus and C. conduplicatus ) can inhibit biofilm formation and reduce preformed biofilms of MSSA and MRSA strains [ 103 , 104 ].…”

“…EOs, volatile compounds extracted from medicinal plants, have shown great therapeutic potential against microbial biofilms [ [102] , [103] , [104] , [105] ]. The EOs extracted from Croton species (e.g., C. blanchetianus and C. conduplicatus ) can inhibit biofilm formation and reduce preformed biofilms of MSSA and MRSA strains [ 103 , 104 ]. Saponins, alkaloids, flavonoids, free steroids, and tannins could be responsible for the eradication of biofilm, since they act by dehydrating the cell wall, disaggregating consolidated colonies, preventing nutrient replacement, and disintegrating the structure of mature biofilm [ 106 ].…”

Synergism of Antimicrobial Activity of Antibiotics With Biocides of Natural Origin

“…Combinations of cumin EO with ciprofloxacin and amoxicycline [15], peppermint with ampicillin and gentamicin [16], cinnamon with amicillin and levometsit [8] and norfloxacin [19], savory with gentamicin [20] croton with oxacillin and ampicillin [21], are promising for combating methicillin-resistant strains of Staphylococcus aureus as evidenced by the FIC indicator (Table 1). It should be noted that in most of the aforementioned studies, researchers attribute the positive effect of combining antibiotics and essential oils to the ability of their main components (terpenes, phenols, alcohols, etc.)…”

“…It should be noted that in most of the aforementioned studies, researchers attribute the positive effect of combining antibiotics and essential oils to the ability of their main components (terpenes, phenols, alcohols, etc.) to damage the cell membrane, leading to intracellular content extravasation [20][21]. They emphasize that the combined use of essential oils with modern antimicrobial drugs is more effective compared to monotherapy, reducing side effects and the required drug dosage.…”

Chemical Composition, Antibacterial and Inhibitory Activity of the Efflux Pump of Essential Oils from Croton piauhiensis Müll.

“…Products of natural origin are important sources in the search for molecules with antibacterial activities [23][24][25]. Furthermore, the combination of a natural compound with an antibiotic could potentialize the antibacterial activity and/or reduce the dose necessary for therapeutic success [24,26].…”