Atividade atimicrobiana e moduladora do óleo essencial das folhas do quimiotipo II de Lippia alba (MILL.) N.E. Brown

Abstract

Popularly known as “ervacidreira”, the Lippia alba (Mill.) N.E. Brown species is a popular plant that is largely used in Brazilian popular medicine to reach many therapeutic goals. Considering the studies that prove the antimicrobial potential (ATM) of the essential oil of L. alba, specially the chemiotype II (OELaII), this study had the goal to evaluate its interference in the action of five antibiotics (Azitromicin (AZI), Ceftriaxone (CEF), Ciprofloxacin (CIP) e Vancomicin (VAN)), used to fight Staphylococcus aureus oxacillin-resistant (ORSA) and Staphylococcus aureus oxacillin-sensitiveinfections. The botanic material, dried leaves of L. alba chemiotype II, was obtained from the Experimental Field, Embrapa Tropical in Paraipaba. The OELaII was obtained by hydrodistillation. The standard strains used on this study were: S. aureus ATCC 6538P and S. aureusATCC 14458 (strains OSSA); S. aureusCCBH 5330 and S. aureusATCC 33591 (strains ORSA). The antimicrobial activity from OELaII and the antibiotics was evaluated using the determination of the Minimum Inhibitory Concentration (MIC) and Minimum Lethal Concentration (MLC). In order to determine the modulating effects (synergism, indifference and antagonism) from OELaII over the antimicrobials, it was used the Checkerboard Method and the Fractional Inhibitory Concentration Indices calculation. The results show that the OELaII MIC to the strains OSSA and OSRA were very close, varying from 312 to 625 µg/mL, as well as the MLC that varied from 312 to 1250 µg/mL. The modulating effect of OELaII demonstrated by the Checkboard Method varied depending on the antibiotic and the tested strain, being VAN the antibiotic with better results, because in 100% of the tested strains was observed synergism of the association between these antibiotics and the essential oil, even in the 1/16 MIC concentration of OELaII and ATM. To the CIP, the association resulted in a synergic effect to 50% of the tested strains, being these strains OXA resistant. To the CEF, the association was indifferent for 100% of the tested strains. The OELaII and AZI association was antagonist for 75% of the strains and indifferent for 25%. The results show that the OELaII modulates positively the antimicrobial action of VAN and CIP, enhancing the efficacy of these ATM. Thereby; the OELaII can be considered a potential candidate to pharmaceutical development, capable of contributing to the antimicrobial resistance control and to the reduction of effective therapeutical doses.