Chemical composition and antibacterial activity of essential oil from leaves of Croton heliotropiifolius in different seasons of the year

This paper reports the first study of the variation of the chemical composition and abundance of the essential oil of Croton heliotropiifolius, in four seasons, and the evaluation of its antibacterial activity. Essential oil obtained from leaves of C. heliotropiifolius were analyzed by GC/MS and evaluated against eight bacteria strains by broth microdilution method. The chemical constituents identified were the same in all samples, but with different proportions. The total percentages identified were 96.58% in summer, 92.08% in autumn, 98.44% in winter and 90.78% in spring. The majors constituents are β-caryophyllene, bicyclogermacrene, germacrene-D, limonene and 1,8-cineole. β-Caryophyllene was the major compound in all samples. The results of the antibacterial evaluations showed weak to moderate activity against the analyzed strains. In all analyzes was observed that essential oil sample collected in summer stands out from the others, displaying stronger activity against Gram-positive as Gram-negative bacteria.