Modulating effect of (+) – α – pinene on the activity of antimicrobials that interfere on protein synthesis and bacterial genetic material

The discovery of new molecules with antimicrobial activity, and the understanding of the mechanisms of action, are important strategies against multiresistant pathogens. The positive enantiomer of α-pinene appears as an alternative to combat them, since it inhibits the growth of microorganisms, including strains of S. aureus, which gives the possibility of its use as an antimicrobial agent, isolated or in combination with other drugs. Therefore, the main goal of this study is to evaluate the modulating effect of (+)–α–pinene on the activity of synthetic antimicrobials that act on protein synthase and interfere with bacterial genetic material. The modulating effect of (+)–α–pinene on the activity of antibiotics for clinical use on some S. aureus strains was studied using the modified disc-diffusion method. The disks contain the following antimicrobials: Ciprofloxacin 5 μg, Tetracycline 30 μg, Nitrofurantoin 300 μg and Rifampicin 5 μg. 50 microliters of (+) - alpha-pinene (160 µL/mL) were added to the disks containing the antimicrobials to verify the modulating effect of monotrepene. Indifferent activity was observed in the association between the phytoconstituent and the four tested antimicrobials. Further studies using new methods in order to evaluate the antimicrobial activity of the association between the (+)–α–pinene and commercial antimicrobials are still needed.


Introduction
Bacterial resistance is a major challenge in global health, affecting both developed and emerging countries, as there is a significant increase in the number of bacterial strains increasingly resistant to antibiotic therapy available today. Thus, the control of infections in the hospital environment is difficult, resulting in prolonged hospitalization, the need to use more expensive medicines and health services, as well as increased mortality of patients, especially the most vulnerable. , such as the elderly, children, Analyzing the data from the 1940s to the mid-1960s, we can find several discoveries of antimicrobials developed from experiments with natural products. These agents have been shown to be efficient in the treatment of gram-positive bacteria, and these substances are present in the antimicrobial classes: β-lactams, aminoglycosides, tetracyclines, macrolides, peptides, among others. (GOODMAN, 2006;GUIMARÃES et al., 2010).
Given this perspective, the positive enantiomer of α-pinene appears as an alternative to combat them, as it has been observed in the literature that it was able to inhibit the growth of microorganisms, http://sciforum.net/conference/mol2net-05 research aims to evaluate the modulating effect of (+)-α-pinene on the activity of synthetic antimicrobials acting on protein synthase and interfering with bacterial genetic material.

Materials and Methods
Phytoconstituent (+) -α -pinene (+ AP) was obtained from the company Sigma-Aldrich do Brasil Ltda and the solutions were prepared at the time of testing, first dissolving them in 1% Tween 80 and 5% DMSO , and using sterile distilled water to achieve desired concentrations (CLEELAND; SQUIRES, 1991). In the performance of the tests to evaluate the phytoconstituent antibacterial activity, the culture medium used was Mueller-Hinton Agar (AMH), (HIMEDIA, India), which was prepared according to the manufacturer's guidelines.

Results and Discussion
As it is oily in nature, preparation of the phytoconstituent dilution was carried out with the aid of After the experiments, it is possible to observe the differences in the average diameter of the inhibition halos (IH) before and after the association with the phytoconstituent. The S. aureus ATCC 25923 strain was found to be sensitive to all antibiotics before and after association with (+) -α-pinene, ie the association with antimicrobials with phytoconstituent did not lead to a qualitative change.
sensitivity profile of the microorganism.
As shown in Figure 1, which shows a comparison between the means of the size of the isolated inhibition halos and in association with the monoterpene, the following diameter values were found for

Conclusions
Given the results obtained, with the indifferent effect found for the four antimicrobials under study, further research using new methodologies is recommended to evaluate the antimicrobial activity of the association between monoterpene and other commercial antimicrobials.