Composição química, atividade antioxidante e antimicrobiana dos óleos essenciais das folhas frescas e secas de Myrceugenia euosma (O.Berg) D.Legrand (Myrtaceae)

Abstract

With the increase in antimicrobial resistance to antibiotics, essential oils (EOs) have gained notoriety, mainly because research has found bioactive compounds with antimicrobial and antioxidant properties, with many pharmacological and industrial applications. Brazil has a wide variety of species that belong to the Myrtaceae family, however, little has been studied about the pharmacological potential of its bioactive compounds. Therefore, the objective of this work was to evaluate the chemical composition, antioxidant and antibacterial activity of EOs from fresh and dried leaves of Myrceugenia euosma (O.Berg) D.Legrand. EOs extraction was carried out from fresh and room temperature dried leaves, by hydrodistillation with a modified Clevenger system. The chemical composition was performed using Gas Chromatography associated with Mass Spectrometry. Antioxidant activity was analyzed by DPPH, ABTS and FRAP methodologies. The antimicrobial activity was evaluated by determining the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) for bacteria of clinical andpharmacological interest in the food, agriculture and industry, including Bacillus cereus, Enterococcus faesium, Listeria monocytogenes, Staphylococcus aureus and Salmonella Typhimurium. The yield of extraction in terms of EO from the fresh leaf was 0.06% and for the dry leaf 0.11%. In the analysis of the chemical composition of the EOs, the major compounds identified in the EO of fresh leaves were spathulenol (17.55%), neointermedeol (11.22%), α-terpineol (9.1%) and eucalyptol (6.08%). In the EO of the dried leaves, α-terpineol (11.54%), spathulenol (10.24%), eucalyptol (10.1%), and neointermedeol (9.11%) were identified. In the antioxidant activity, in general, the EOs showed low activities, with little difference between fresh leaves and dried leaves. Inhibitory antimicrobial activity was found for both EOs against all tested microorganisms, in which the minimum concentration values were 0.098 - 0.781 mg/mL. As for MBC values, the lowest concentrations with bactericidal action were registered for the EO of fresh leaves, with values of 0.098 mg/mL - 0.195 mg/mL. Finally, great diversity of compounds was found in the chemical composition of EOs, low antioxidant activity and high antimicrobial activity, and to the best of our knowledge, this is the first study recorded for M. euosma, considering it as a promising source of bioactives with possible biotechnological application.