Antimicrobial, modulatory and chemical analysis of the oil of Croton limae

Abstract

Context: Croton sp. are plants with a well-reported antimicrobial activity. Croton limae A.P. Gomes, M.F. Sales P.E. Berry (Euphorbiaceae), known as ‘marmeleiro-prateado’, is commonly used to manage abdominal pain in Brazil.

Objective: This work evaluates the phytochemical composition, antimicrobial and modulatory activities of the essential oil of C. limae leaves (EOCL).

Materials and methods: The minimum inhibitory concentration (MIC) and the modulation of the antibiotic activity were determined using a microdilution method. The concentration of EOCL ranged between 512 and 8 μg/mL. Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Candida tropicalis, C. krusei and C. albicans strains were used in the MIC and modulation assays. The antibiotics, amikacin, gentamicin and neomycin, and the antifungals, amphotericin B, benzoylmetronidazole and nystatin, were used in concentrations ranging between 2500 and 2.5 μg/mL. The phytochemical analysis of the EOCL was performed through gas chromatography coupled to a mass spectrometer (GC/MS).

Results: Only Staphylococcus aureus was inhibited by a clinically relevant concentration of EOCL (MIC 512 μg/mL). Synergism between the EOCL and amikacin against S. aureus (9.76 μg/mL) and E. coli (39.062 μg/mL); neomycin against E. coli (2.44 μg/mL); and benzoylmetronidazole against C. krusei (256 μg/mL) were observed. The GC/MS analysis identified cedrol, eucalyptol and α-pinene as the main compounds of EOCL.

Conclusion: EOCL inhibited the growth of S. aureus and potentiated the antibiotic and antifungal effects of drugs against all bacterial and Candida strains, respectively.

Keywords:

• Marmeleiro-prateado
• Staphylococcus aureus
• Escherichia coli; Pseudomonas aeruginosa
• Klebsiella pneumonia
• Candida tropicalis
• Candida krusei
• Candida albicans
• essential leaf oil
• chemical constituents

Acknowledgements

We would like to thank Dr. Margareth Ferreira de Sales at the Herbarium Sérgio Tavares (HST) of the Federal Rural University of Pernambuco (UFRPE) for the botanical identification, the team at the Laboratory of Research in Natural Products (LPPN) for their contribution to the essential oil extraction, the team at the Laboratory of Microbiology and Molecular Biology for their help in the carrying out of the microbiological tests, and the Federal University of Piaui for the essential oil analysis.

Disclosure statement

The authors report that they have no conflicts of interest.

Additional information

Funding

The financial support was provided by the institution Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico (FUNCAP).