Promising natural preservatives from Lippia origanoides essential oils (Verbenaceae)

As preservatives in food and medicines have been related to damages to human health, food and pharmaceutical industries have been suffering a broad pressure from consumers in order to reduce or even avoid the use of chemical preservatives in their products. An interesting alternative is the use of more effective and safer preservatives than the current ones. In light of these facts, the aim of this work is to evaluate the antimicrobial activity of essential oils of Lippia origanoides (Q1 and Q2) in combination for development of new natural preservatives. The essential oils were obtained by hidrodistillation of dried leaves, using a Clevenger apparatus, for 2 hours. Qualitative and quantitative analyses of the oils were carried out by gas chromatography and mass spectrometry (GC/MS). The identification of substances was performed by comparing their mass spectra with the database of the GC/MS (Nist 62 lib.) and Kovats retention index. Antimicrobial assays were conducted by using the microdilution method in 96- well-plates, according to the CLSI standards. Analysis of the essential oils showed presence of carvacrol (48%) and endo-fenchol (61%) the major constituents of L. origanoides Q1 and Q2 respectively. The synergistic combinations with the highest spectrum of antimicrobial activity were 0.312µL.mL-1 for essential oil of Q1 and 0.625µL.mL^-1 for Q2, reaching all microorganisms except for C. albicans, for which the former (0.312µL.mL^-1) was one of the two oils promoting a synergistic effect. These results have shown that both quimiotypes of L. origanoides are promising new preservatives.