Composição química e concentração mínima bactericida de dezesseis óleos essenciais sobre Escherichia coli enterotoxigênica

Abstract

RESUMO:Este trabalho teve por objetivo avaliar o efeito bactericida in vitro de dezesseis óleos essenciais sobre Escherichia coli enterotoxigênica (ETEC). Dentre os óleos essenciais estudados, três foram extraídos in situ por arraste a vapor e treze foram adquiridos comercialmente. Todos os óleos foram analisados por CG-EM e CG-DIC. A atividade bactericida foi avaliada pelo método de microdiluição utilizando-se caldo triptona de soja e microplacas de poliestireno de 96 poços, com posterior plaqueamento das culturas em ágar triptona de soja. Os óleos essenciais de Cinnamomum cassia e de Thymus vulgaris apresentaram concentração mínima bactericida (CMB) de 0,12% e 0,25%, respectivamente. Já os óleos comerciais de Syzygium aromaticum e Origanum vulgare apresentaram ambos CMB de 0,50% e os óleos extraídos in situ de Cymbopogon citratus e Origanum vulgare apresentaram ambos CMB de 1,00%. Os dezesseis óleos essenciais apresentaram composição química qualitativa e quantitativa distintas. As análises químicas dos óleos essenciais de Cinnamomum cassia e de Thymus vulgaris tiveram a presença majoritária de E-cinamaldeído (84,52%) e timol (50,89%). Conclui-se que os óleos de C. cassia e T. vulgaris foram os mais eficazes na inibição do crescimento in vitro dessa bactéria, a qual possui diferentes níveis de sensibilidade dependendo da composição química do óleo. Palavras-chave:Patógeno alimentar, ETEC, antimicrobianos naturais, atividade bactericida, cromatografia gasosa.ABSTRACT: Determination of minimum bactericidal concentration of sixteen essential oils on enterotoxigenic Escherichia coli. This study aimed to evaluate the bactericidal effect in vitro of sixteen essential oils on enterotoxigenic Escherichia coli (ETEC). Among the essential oils, three were extracted in situ by steam distillation and thirteen were purchased commercially. All oils were analyzed by GC-MS and GC-FID. The bactericidal activity was evaluated by the microdilution method using tryptone soy broth, and 96-well polystyrene microplates with subsequent plating of the cultures in tryptone soy agar. Cinnamomum cassia and Thymus vulgaris essential oils showed minimal bactericidal concentration (MBC) 0.12% and 0.25%, respectively. Both commercial oils of Syzygium aromaticum and Origanum vulgare showed MBC of 0.50% and the oils extracted in situ Origanum vulgare and Cymbopogon citratus showed both MBC of 1.00%. The sixteen essential oils pointed out distinct qualitative and quantitative chemical composition. Chemical analysis of Cinnamomum cassia and Thymus vulgaris oils had the predominant presence of E-cinnamaldehyde (84.52% ± 0.07%) and thymol (50.89% ± 0.31%). In conclusion, T. vulgaris and C. cassia oils were the most effective in inhibiting in vitro growth of this bacterium, which has different sensitivity levels depending on the chemical composition of the oil.

Antifungal activity of essential oils from Cinnamomum cassia, Myristica fragrans and Syzygium aromaticum against Rhodotorula mucilaginosa

“…These results corroborate the present study, where antifungal activity against Rhodotorula mucilaginosa was also proven (Table 4). (42,53). Thus, the presence of Ecinnamaldehyde and eugenol identified in the chemical composition of the Cinnamomum cassia and Syzygium aromaticum essential oils, respectively, may be associated with the potential antifungal activity against R. mucilaginosa observed in the present study, aiming at the prospect of new therapeutic agents.…”

Control of Enterotoxigenic <i>Escherichia coli</i> in Ground Beef by Blends of Essential Oils

“…Studies with carvacrol have shown that its presence in a culture medium promotes the release of lipopolysaccharides from the external membrane and interferes with the permeability of the cytoplasmic membrane to ions [8]. Carvacrol (30 mg/mL) proved to be effective in inhibiting the growth of E. coli inoculated in beef carcass [25]. However, the presence of other components, in addition to carvacrol and thymol, even at low concentrations, may promote synergistic, additive, or antagonistic interactions [26].…”

Antibacterial activity and in vivo wound healing potential of phenolic extracts from jaboticaba skin

“…In the literature, there is not a single criterion for assessing the effectiveness of antimicrobial activity of plant extracts; therefore, the mechanism of action of phenolic compounds on pathogenic bacteria is not yet well established. It is believed that hydrophobic phenols may act by changes in cell membrane permeability . However, further investigations are needed to clarify the mechanisms of action of these compounds.…”