CONICET | Buscador de Institutos y Recursos Humanos

Essential oils (EOs) are aromatic components obtained from different plant parts such as leaves, fruits and flower, and are composed of secondary metabolites such as terpenes and terpenoids. These compounds act as a mechanism of defense against pathogen attack (microbes, herbivores or competing plants). A great deal of essential oils is used in different industries, mainly in perfumes (fragrances), food (as flavoring and preservatives), pharmaceuticals (therapeutic action) and for centuries in traditional medicine1. It is well known that some essential oils exert antimicrobial and antioxidant properties2-3 Schinus is a genus belonging to the Anacardiaceae family. This family comprises about 70 genera and 600 species. They are used traditionally as a healing, stomachic and antidiarrheal agent, due to the presence of tannins and oil resins. In this family, S. molle L. (also known as California pepper and pink pepper) was introduced from South America to most tropical and subtropical areas of the world, as well as the Mediterranean. Another tree of this genus, S. areira L. commonly called peppertree, molle and aguaribay, is a native plant from South America and nowadays it is distributed through Argentina, south-eastern of Brazil, Peru, Colombia, Ecuador, Uruguay and widely distributed in Mexico, Central and Southern of California and West Texas, United States. Several parts of this tree are used in traditional medicine as antibacterial, antifungal and antirheumatic4. Extensively studies regarding the characterization of EOs isolated from the Schinus molle has been reported, however much less research has been done on the biological properties of the oils of S. areira5. Moreover, significant variations in the chemical composition of the EOs of S. areira have been reported in relation to the geographic origin5, although correlation between the presence and content of specific compounds and the antimicrobial activity has not been deeply investigated. The aim of this work was to characterize the antibacterial activity of EOs isolated from leaves and fruits of S. areira trees with different chemical profile. EOs were obtained by distillation of dried leaves and fruits and their chemical composition were determined by gas chromatography (GC)/FID and GC/MS as previously described6. A microplate bioassay for quick and sensitive determination of antibacterial activity was used.7 The antibacterial activity was assayed against the human pathogenic bacteria Staphylococcus aureus ATCC 25923 and against a methicillin-resistant S. aureus strain (MRSA). Results showed that the EO isolated from fruits and leaves showed high antibacterial effect on S. aureus. The inhibitory effect of both fractions on the bacterial growth decreases with increasing dilutions, demonstrating direct proportionality between concentrations of components and the antibacterial activity. The EO of fruits have a greater inhibitory effect than the leaves. Notably, the S. areira oil was able to inhibit the bacterial growth of SAMR strain, which caused a large number of deaths in hospitalized patients every year worldwide. The minimal inhibition concentrations obtained for fruits and leaves were from 3.2 µL/mL to 15.0 µL/mL. In conclusion, our findings demonstrated the potential use of the oils against Staphylococcal infections. 1. Bakkali et al. (2008) Food Chem Toxicol 46 (2): 446?475. 2. Burt (2004) Int. J. Food Microbiol 94: 223?253. 3. Hosnia et al. (2011) Crops and Products 34: 1622?1628. 4. Mendonça Rocha et al. (2012) Molecules 17: 12023-12036. 5. Viturro C et al. (2010). Proyecto CYTED IV. 20, Edit. Universitária da PUCRS. Chapter 10. 6. Ojeda-Sana et al. (2013). Food Control 31: 189-192. This research was supported by the National Agency of Scientific and Technological Promotion, Argentina: Grant PICTO 00150 and the National Council for Scientific and Technological Research (CONICET), Argentina. S. M. is a member of the Research Scientific Career from CONICET.