Antimicrobial activity of the essential oils from the leaves of two morphotypes of Croton cajucara Benth

Abstract

Croton cajucara Benth. (Euphorbiaceae) is a shrub native to Amazon region and locally known as sacaca. Two morphotypes are known, namely white ‘sacaca’ and red ‘sacaca’. The essential oils from the leaves of these morphotypes are rich in linalool and 7-hydroxycalamenene, respectively. The effectiveness of the oils from forty individuals from a germplasm bank regarding the antimicrobial activity against Staphylococcus aureus and Candida albicans was investigated by drop diffusion (or agar diffusion) method. Expressive inhibition zones for both microorganisms tested were observed. Essential oils rich in 7-hydroxycalamenene were more effective against S. aureus while linalool-rich essential oils acted inhibiting C. albicans. The minimal inhibitory (MIC) and microbicidal concentrations of the main constituents of the oils were also determined, using broth dilution assay. It was observed that isolated 7-hydroxycalamenene presented high bactericidal activity, with a MIC of 0.3 μg/mL, while for fungicidal activity a MIC of 45 μg/mL was recorded. For S. aureus, the isolated 7-hydroxycalamenene was more active than the whole oil, whereas the linalool-rich essential oil presented higher bactericide activity than pure linalool. For C. albicans, however, pure linalool was more active than the whole essential oil.

Keywords:

• antimicrobial activity
• essential oil composition
• Croton cajucara
• Candida albicans
• Staphylococcus aureus
• linalool
• 7-hydroxycalamenene

Acknowledgements

This work was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ) and Universidade Federal do Rio de Janeiro (UFRJ).