Chemical composition and modulation of bacterial drug resistance of the essential oil from leaves of Croton grewioides

Abstract

The essential oil from leaves of Croton grewioides Baill was obtained by hydrodistillation using Clevenger apparatus, and its chemical composition was analyzed by GC-MS, where 18 compounds were identified, mostly as monoterpenes (55.56%) and sesquiterpenes (44.44%), in which the major constituent was the α-pinene (47.43%). The essential oil of Croton grewioides (EOCg) and its major compound (α-pinene) were evaluated as modulators of antibiotic resistance in strain SA-1199B and IS-58 of Staphylococcus aureus that overexpresses efflux protein. The minimum inhibitory concentrations (MICs) of the antibiotics were determined by the microdilution assay in the absence and in the presence of sub-inhibitory concentration of EOCg and α-pinene. Although the EOCg and α-pinene did not indicate relevant antibacterial activity in vitro, they acted as antibiotic resistance modulators, i.e., EOCg in combination with norfloxacin, reducted its MIC, by 64× whereas in combination with tetracycline it was observed a reduction of 4×. Additionally, it was observed a MIC reduction of tetracycline by 32×, when combined with α-pinene. The results suggest that EOCg and α-pinene modulate or even reverse bacterial resistance as a putative efflux pump inhibitor.

Nanoencapsulation of buriti oil (Mauritia flexuosa L.f.) in porcine gelatin enhances the antioxidant potential and improves the effect on the antibiotic activity modulation

“…Due to the emergence of multidrug-resistant strains to antibiotics, combined drugs are used against these resistance mechanisms [70]. Antimicrobial resistance, in general, alters antibiotic action through the following mechanisms: modification of the antimicrobial target (decreased drug affinity), decreased drug absorption, activation of efflux mechanisms to expel the harmful compound (overexpression efflux pumps), or global changes in critical metabolic pathways through the modulation of regulatory networks [71]. One example is plant extracts that exhibit synergistic activity against microorganisms, as they present a complex mixture of natural products and present a low risk in the development of bacterial resistance [72].…”

Piper rivinoides Kunth: A medicinal plant that preserves bioactive chemical substances in its essential oil throughout the seasons

“…There are numerous other studies in the literature describing the biological potential of α and β-pinene monoterpenes (Medeiros et al, 2017;Pereira et al, 2017;Da França et al, 2015;Rivera-Yañez et al, 2017).…”

Aspectos e potencialidades biológicas do gênero Croton (Euphorbiaceae)

“…Estudo utilizando o óleo essencial das folhas de C. grewioides comprovou atividade moduladora de resistência a antibióticos do mesmo contra as linhagens AS-1199B e IS-58 de Staphylococcus aureus. Para os testes foram feitas a associações do óleo essencial do C. grewioides com norfloxacina gerando redução na sua concentração inibitória mínima de 64× e em associação com tetraciclina foi notada uma diminuição de 4×, quando combinada tetraciclina com α-pineno( principal constituinte óleo) houve redução na concentração mínima de 32×, caracterizando que tanto o óleo essencial quanto α-pipeno são capazes de modular ou até mesmo reverter a resistência bacteriana (MEDEIROS et al, 2017).…”