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Modulating Effect of 4,6,6-trimethylbicyclo [3.1.1] hept-3-ene on Antimicrobials Used to Combat Escherichia coli
1 , 1 , 2 , * 3
2  Agricultural Defense Agency of Piauí (ADAPI)
3  Teacher Training Center (CFP) - Federal University of Campina Grande - Cajazeiras - Paraíba - Brazil.


The growing number of resistant microorganisms is considered a global public health problem. In this context, several control initiatives have been proposed, such as the preparation of medicines from the herbal raw material that may have an antibacterial and antifungal effect as an alternative to fight against pathogens such as Escherichia coli, which is related to approximately 50% of hospital infections. Among the monoterpenes with antibacterial potential, there is the potential enantiomer of α-pinene, which has antimicrobial activity against some microorganisms. The aim of this research was to evaluate the modulating effect of (+) - α-pinene on the activity of synthetic antimicrobials acting on the bacterial cell wall. The phytoconstituent (+) - α - pinene obtained from Sigma-Aldrich Brazil LTDA. The solutions were dissolved in 1% Tween 80 and 5% DMSO. Sterile distilled water was used to achieve the desired concentrations. The tests were carried out on the E. coli strain ATTC 25922. For the modulation and adaptation tests, discs containing commercial antimicrobial (ATMs) acting on the bacterial cell wall were used: cephalothin, ceftazidime, amoxicillin, ampicillin, cefepime, cefoxitin , meropenem and cefuroxime. The modulating action of monoterpene was determined by the disc diffusion method. After incubation of the plates at 35 + 2 °C for 24 hours, the diameters of the inhibition halos of microbial growth were measured. Applying the classification proposed by Cleeland and Squires for the effect of interaction between the substances, we could classify the effect of the association of the phytoconstituent for the ATMs ceftazidime, amoxicillin, cefepime and cefoxitina as a synergistic effect. However, for the other ATMs, there was no statistically significant difference, and the association effect was classified as indifferent. It is concluded that the phytoconstituent (+) - α-pinene, has synergistic effects with some drugs tested in this work and can be suggested as a promising associated and potentiating substance against E. coli ATCC 25922, provided that it is subjected to tests that verify its toxic potential for humans. In the same way, the association of this monoterpene with the antibiotics that have antagonistic or indifferent effects in this study should be avoided, thus not allowing the growth of resistant bacterial strains.

Keywords: Bacterial resistance, modulation, pinene, Escherichia coli.