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BioMed Research International
Volume 2014, Article ID 305610, 7 pages
Research Article

Phytochemical Prospection and Modulation of Antibiotic Activity In Vitro by Lippia origanoides H.B.K. in Methicillin Resistant Staphylococcus aureus

1Laboratory of Microbiology and Immunology, Campus Amílcar Ferreira Sobral, Universidade Federal do Piauí, BR 343, Km 3,5 Bairro Meladão, 64800-000 Floriano, PI, Brazil
2Center for Research on Medicinal Plants, Universidade Federal do Piauí, Bairro Ininga, 64049-550 Teresina, PI, Brazil
3Laboratory of Clinical Microbiology, Universidade Federal da Paraiba, Cidade Universitária, 58051-900 João Pessoa, PB, Brazil
4Laboratory of Microbiology, Faculdade de Ensino Superior de Floriano, Bairro Manguinha, 64800-000 Floriano, PI, Brazil
5Laboratory of Microbiology and Molecular Biology, Regional University of Cariri, Bairro Pimenta, 63105-100 Crato, CE, Brazil
6Laboratory of Natural Products, Universidade Federal do Piauí, Bairro Ininga, 64049-550 Teresina, PI, Brazil

Received 8 December 2013; Revised 6 January 2014; Accepted 6 January 2014; Published 10 February 2014

Academic Editor: Aramati B. Reddy

Copyright © 2014 Humberto Medeiros Barreto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The Lippia origanoides H.B.K. ethanol extract (LOEE) and hexane (LOHEX), dichloromethane (LODCM), and ethyl acetate (LOEA) fractions were tested for their antimicrobial activity alone or in combination with antibiotics against a methicillin resistant Staphylococcus aureus (MRSA) strain. The natural products did not show antimicrobial activity against multidrug resistant strain at the clinically significant concentrations tested. However, a modulatory effect in the antibacterial activity of the neomycin and amikacin was verified when LOEE, LOHEX and LODCM were added to the growth medium at subinhibitory concentrations. A similar modulation was found when the natural products were changed for chlorpromazine, an inhibitor of bacterial efflux pumps, suggesting the involvement of resistance mediated by efflux system in the MRSA tested. The fractions LOHEX and LODCM showed a modulatory activity bigger than their majority compounds (carvacrol, thymol, and naringenin), indicating that this activity is not due to their majority compounds only, but it is probably due to a synergism between their chemical components. These results indicate that L. origanoides H.B.K. can be a source of phytochemicals able to modify the phenotype of resistance to aminoglycosides in MRSA.