Chemical composition, antioxidant and antimicrobial activities of essential oil extracted from Myrceugenia euosma (O. Berg) D. Legrand (Myrtaceae)

Abstract

Essential oils (EOs) have gained notoriety due to their potential to suppress pathogenic microorganisms capable of resisting to antibiotics. It mainly happened because studies have found bioactive compounds with antimicrobial and antioxidant properties that can be used in several pharmacological and industrial applications. Brazil has a wide variety of plant species belonging to family Myrtaceae; however, studies about the pharmacological potential of its bioactive compounds remain scarce. Therefore, the aim of the current study is to investigate the chemical composition, as well as the antioxidant and antibacterial activity, of EOs extracted from fresh and dry Myrceugenia euosma (O. Berg) D. Legrand leaves. EOs were extracted both from fresh and room temperature-dried leaves, which were subjected to hydrodistillation in modified Clevenger system. EOs’ chemical composition was analyzed through Gas Chromatography coupled to Mass Spectrometry. Antioxidant activity was analyzed based on the DPPH, ABTS and FRAP methodologies. Antimicrobial activity was assessed based on determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of bacteria of clinical and pharmacological interest to the food, agricultural and industrial sectors, such as Bacillus cereus, Enterococcus faesium, Listeria monocytogenes, Staphylococcus aureus and Salmonella Typhimurium. Fresh-leaf EO extraction yield reached 0.06%, whereas dry-leaf EO extraction yield reached 0.11%. Based on EOS’ chemical composition analysis, spathulenol (17.55%), neointermedeol (11.22%), α-terpineol (9.1%) and eucalyptol (6.08%) were the major compounds identified in EO extracted from fresh leaves. On the other hand, α-terpineol (11.54%), spathulenol (10.24%), eucalyptol (10.1%) and neointermedeol (9.11%) were identified in EO extracted from dry leaves. Overall, the analyzed EOs have shown low antioxidant activity; there was little difference between EOs extracted fresh leaves and those extracted from dry leaves. Antimicrobial activity capable of inhibiting all tested microorganisms was observed for both EO types - MIC values ranged from 0.098 mg/mL to 0.781 mg/mL. With respect to MBC, the lowest concentrations with bactericidal action were recorded for EO extracted from fresh leaves - values ranged from 0.098 mg/mL to 0.195 mg/mL. Finally, great compound diversity was observed in the chemical composition of the investigated EOs, which presented low antioxidant activity and high antimicrobial activity. To the best of our knowledge, the current study was the first to investigate M. euosma as promising source of bioactives with potential for biotechnological application.