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An in vitro synergistic interaction of combinations of Thymus glabrescens essential oil and its main constituents with chloramphenicol.

Ilić BS, Kocić BD, Cirić VM, Ćvetković OG, Miladinović DL - ScientificWorldJournal (2014)

Bottom Line: The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains, but the activities were lower than those of the standard antibiotic and thymol.A combination of T. glabrescens oil and chloramphenicol produced a strong synergistic interaction (FIC indices in the range 0.21-0.87) and a substantial reduction of the MIC value of chloramphenicol, thus minimizing its adverse side effects.The combinations geraniol-chloramphenicol and thymol-chloramphenicol produced synergistic interaction to a greater extent, compared with essential oil-chloramphenicol association, which may indicate that the activity of the thyme oil could be attributed to the presence of significant concentrations of geraniol and thymol.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, Faculty of Medicine, University of Niš, 18000 Niš, Serbia.

ABSTRACT
The chemical composition and antibacterial activity of Thymus glabrescens Willd. (Lamiaceae) essential oil were examined, as well as the association between it and chloramphenicol. The antibacterial activities of geraniol and thymol, the main constituents of T. glabrescens oil, individually and in combination with chloramphenicol, were also determined. The interactions of the essential oil, geraniol, and thymol with chloramphenicol toward five selected strains were evaluated using the microdilution checkerboard assay in combination with chemometric methods. Oxygenated monoterpenes were the most abundant compound class in the oil, with geraniol (22.33%) as the major compound. The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains, but the activities were lower than those of the standard antibiotic and thymol. A combination of T. glabrescens oil and chloramphenicol produced a strong synergistic interaction (FIC indices in the range 0.21-0.87) and a substantial reduction of the MIC value of chloramphenicol, thus minimizing its adverse side effects. The combinations geraniol-chloramphenicol and thymol-chloramphenicol produced synergistic interaction to a greater extent, compared with essential oil-chloramphenicol association, which may indicate that the activity of the thyme oil could be attributed to the presence of significant concentrations of geraniol and thymol.

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PCA and HCA of the antibacterial activity of the studied combinations {T. glabrescens oil-chloramphenicol (*); geraniol-chloramphenicol (**); thymol-chloramphenicol (***)} based on their FIC values: (a) eigenvalues of the correlation matrix, (b) the loading plot of the responsible FIC values, (c) the score plot of the examined bacteria, and (d) the corresponding dendrogram. The examined FIC values are presented in Figures 1–3.
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fig4: PCA and HCA of the antibacterial activity of the studied combinations {T. glabrescens oil-chloramphenicol (*); geraniol-chloramphenicol (**); thymol-chloramphenicol (***)} based on their FIC values: (a) eigenvalues of the correlation matrix, (b) the loading plot of the responsible FIC values, (c) the score plot of the examined bacteria, and (d) the corresponding dendrogram. The examined FIC values are presented in Figures 1–3.

Mentions: PCA and HCA were applied on all FIC data (Figures 1–3) in order to evaluate similar antibacterial behaviour among studied combinations. According to the eigenvalues of the obtained correlation matrix, the PC1 horizontal axis explained 81.14% of the total variance among the tested interactions, while the PC2 vertical axis showed a further 12.77% (Figure 4(a)). The loading plot (Figure 4(b)) illustrates the influence of the FIC values, marked by FICA equivalents, responsible for the classification of the interaction in the score plot (Figure 4(c)). Based on the Euclidean distance and dissimilarity ≥0.42 (Figure 4(d)), the HCA method indicated two groups of interaction (A and B). Group A, constituted only by S. aureus ATCC 29213, was characterized mainly by strong antagonistic interactions with the applied combinations. In this group, only the association thymol-chloramphenicol showed some percent of synergistic interaction. In contrast, in group B, formed by the rest of the examined bacteria strains and studied combinations, mainly synergistic or additive interactions were detected.


An in vitro synergistic interaction of combinations of Thymus glabrescens essential oil and its main constituents with chloramphenicol.

Ilić BS, Kocić BD, Cirić VM, Ćvetković OG, Miladinović DL - ScientificWorldJournal (2014)

PCA and HCA of the antibacterial activity of the studied combinations {T. glabrescens oil-chloramphenicol (*); geraniol-chloramphenicol (**); thymol-chloramphenicol (***)} based on their FIC values: (a) eigenvalues of the correlation matrix, (b) the loading plot of the responsible FIC values, (c) the score plot of the examined bacteria, and (d) the corresponding dendrogram. The examined FIC values are presented in Figures 1–3.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3926437&req=5

fig4: PCA and HCA of the antibacterial activity of the studied combinations {T. glabrescens oil-chloramphenicol (*); geraniol-chloramphenicol (**); thymol-chloramphenicol (***)} based on their FIC values: (a) eigenvalues of the correlation matrix, (b) the loading plot of the responsible FIC values, (c) the score plot of the examined bacteria, and (d) the corresponding dendrogram. The examined FIC values are presented in Figures 1–3.
Mentions: PCA and HCA were applied on all FIC data (Figures 1–3) in order to evaluate similar antibacterial behaviour among studied combinations. According to the eigenvalues of the obtained correlation matrix, the PC1 horizontal axis explained 81.14% of the total variance among the tested interactions, while the PC2 vertical axis showed a further 12.77% (Figure 4(a)). The loading plot (Figure 4(b)) illustrates the influence of the FIC values, marked by FICA equivalents, responsible for the classification of the interaction in the score plot (Figure 4(c)). Based on the Euclidean distance and dissimilarity ≥0.42 (Figure 4(d)), the HCA method indicated two groups of interaction (A and B). Group A, constituted only by S. aureus ATCC 29213, was characterized mainly by strong antagonistic interactions with the applied combinations. In this group, only the association thymol-chloramphenicol showed some percent of synergistic interaction. In contrast, in group B, formed by the rest of the examined bacteria strains and studied combinations, mainly synergistic or additive interactions were detected.

Bottom Line: The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains, but the activities were lower than those of the standard antibiotic and thymol.A combination of T. glabrescens oil and chloramphenicol produced a strong synergistic interaction (FIC indices in the range 0.21-0.87) and a substantial reduction of the MIC value of chloramphenicol, thus minimizing its adverse side effects.The combinations geraniol-chloramphenicol and thymol-chloramphenicol produced synergistic interaction to a greater extent, compared with essential oil-chloramphenicol association, which may indicate that the activity of the thyme oil could be attributed to the presence of significant concentrations of geraniol and thymol.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, Faculty of Medicine, University of Niš, 18000 Niš, Serbia.

ABSTRACT
The chemical composition and antibacterial activity of Thymus glabrescens Willd. (Lamiaceae) essential oil were examined, as well as the association between it and chloramphenicol. The antibacterial activities of geraniol and thymol, the main constituents of T. glabrescens oil, individually and in combination with chloramphenicol, were also determined. The interactions of the essential oil, geraniol, and thymol with chloramphenicol toward five selected strains were evaluated using the microdilution checkerboard assay in combination with chemometric methods. Oxygenated monoterpenes were the most abundant compound class in the oil, with geraniol (22.33%) as the major compound. The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains, but the activities were lower than those of the standard antibiotic and thymol. A combination of T. glabrescens oil and chloramphenicol produced a strong synergistic interaction (FIC indices in the range 0.21-0.87) and a substantial reduction of the MIC value of chloramphenicol, thus minimizing its adverse side effects. The combinations geraniol-chloramphenicol and thymol-chloramphenicol produced synergistic interaction to a greater extent, compared with essential oil-chloramphenicol association, which may indicate that the activity of the thyme oil could be attributed to the presence of significant concentrations of geraniol and thymol.

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