Evaluation of the antimicrobial activity of Cinnamomum zeylanicum essential oil and trans-Cinnamaldehyde against resistant Mycobacterium tuberculosis

Mota, Aquiles Paulino Peres; Campelo, Thales Alves; Frota, Cristiane Cunha

The essential oil (EO) extracted from the bark of Cinnamomum zeylanicum (Czey; also known as cinnamon), mostly derives its properties from its major compound trans-cinnamaldehyde (TCin). The present study evaluated the antimycobacterial activity of the essential oil from Czey (CzeyEO) and TCin against sensitive and resistant clinical isolates of Mycobacterium tuberculosis, as well as the combinatorial effects of CzeyEO and TCin with the anti-tuberculosis (TB) drugs rifampicin (RIF) and isoniazid (INH). The resazurin microtiter assay method was used to determine the minimum inhibitory concentration (MIC) of the components tested on the clinical isolates of M. tuberculosis. The effects of the CzeyEO/RIF, CzeyEO/INH, TCin/RIF, and TCin/INH combinations on the M. tuberculosis H37Rv reference strain were evaluated using the checkerboard method to determine the fractional inhibitory concentration index (FICI). CzeyEO and TCin inhibited all bacterial clinical isolates. In the interactive experiment, CzeyEO and TCin were found to be highly effective in reducing the resistance of resistant M. tuberculosis to RIF and INH. All four tested combinations demonstrated synergistic and additive effects, with no antagonistic effects. The synergistic combinations of CzeyEO/RIF and CzeyEO/INH exhibited FICI values of 0.375 and 0.5, respectively, while the TCin/RIF and TCin/INH combinations exhibited FICI values of 0.31 and 0.5, respectively. These results indicate that CzeyEO and TCin are potential candidates for the treatment of drug-resistant tuberculosis in combination therapy with INH and RIF.

O óleo essencial (EO) extraído da casca do Cinnamomum zeylanicum (CzeyEO), conhecido como canela, tem como seu principal composto o trans-cinamaldeído (TCin). O presente estudo avaliou a atividade antimicobacteriana de CzeyEO e do TCin contra isolados clínicos sensíveis e resistentes de Mycobacterium tuberculosis, bem como os efeitos das associações de CzeyEO e do TCin com os fármacos anti-TB, rifampicina (RIF) e isoniazida (INH). A técnica de ensaio de microtitulação da resazurina foi utilizada para determinar a concentração inibitória mínima (CIM) dos componentes testados nos isolados clínicos de M. tuberculosis. Os efeitos das associações CzeyEO/RIF, CzeyEO/INH, TCin/RIF e TCin/INH contra a cepa de referência H37Rv de M. tuberculosis foram avaliados pelo método Checkerboard, determinando o índice de concentração inibitória fracionária (ICIF). Todos os isolados clínicos bacterianos foram inibidos por CzeyEO e TCin. As interações de CzeyEO e TCin foram altamente eficazes na redução da resistência do M. tuberculosisresistente a RIF e INH. Todas as quatro combinações testadas resultaram em efeitos sinérgicos e aditivos, sem efeito antagônico. Ambas as associações de sinergismo de CzeyEO/RIF e CzeyEO/INH mostraram valores de ICIF de 0,375 e 0,5, enquanto as associações de TCin/RIF e TCin/INH apresentaram valores de ICIF de 0,31 e 0,5. CzeyEO e TCin são potenciais candidatos em terapia combinada com INH e RIF para o tratamento da tuberculose resistente.