Chemical composition, antioxidant and antibacterial activities of essential oils from leaves and flowers of Eugenia klotzschiana Berg (Myrtaceae)

ABSTRACT Many essential oils (EOs) of different plant species possess interesting antimicrobial effects on buccal bacteria and antioxidant properties. Eugenia klotzschiana Berg (pêra-do-cerrado, in Portuguese) is a species of Myrtaceae with restricted distribution in the Cerrado. The essential oils were extracted through the hydrodistillation technique using a modified Clevenger apparatus (2 hours) and chemically characterized by GC-MS. The major compounds were α-copaene (10.6 %) found in oil from leaves in natura, β-bisabolene (17.4 %) in the essential oil from dry leaves and α-(E)-bergamotene (29.9 %) in oil from flowers. The antioxidant activity of essential oils showed similarities in both methods under analysis (DPPH and ABTS˙+) and the results suggested moderate to high antioxidant activity. The antibacterial activity was evaluated by determining minimum inhibitory concentrations (MICs), using the microdilution method. MIC values below 400 µg/mL were obtained against Streptococcus salivarius (200 µg/mL), S. mutans (50 µg/mL), S. mitis (200 µg/mL) and Prevotella nigrescens (50 µg/mL). This is the first report of the chemical composition and antibacterial and antioxidant activities of the essential oils of E. klotzschiana. These results suggest that E. klotzschiana, a Brazilian plant, provide initial evidence of a new and alternative source of substances with medicinal interest.

Determination of phenolic profile by HPLC-ESI-MS/MS and anti-inflammatory activity of crude hydroalcoholic extract and ethyl acetate fraction from leaves of Eugenia brasiliensis

ABSTRACT Eugenia brasiliensis Lam., Myrtaceae, is used in folk medicine for anti-inflammatory diseases such as arthritis and rheumatism. This study investigated the anti-inflammatory activity and phenolic profile of the crude hydroalcoholic extract and ethyl acetate fraction from E. brasiliensis leaves. Crude hydroalcoholic extract and the ethyl acetate fraction were analyzed by HPLC-ESI-MS/MS in comparison to standard phenolic compounds. The anti-inflammatory activity of the crude hydroalcoholic extract (1, 10 and 25 mg kg-1) and the ethyl acetate fraction (10, 25 and 50 mg kg-1) was evaluated in a swiss mouse model of acute pleurisy induced by carrageenan, being the total cell count, exudation and analysis of nitrite/nitrate the inflammation parameters. HPLC-ESI-MS/MS analysis revealed apigenin, catechin, galangin, isoquercetin, myricetin, quercetin and rutin. Crude hydroalcoholic extract and ethyl acetate fraction were effective in inhibiting cell migration in all tested doses. Crude hydroalcoholic extract was effective in inhibiting exudation only at the 10 mg kg-1 dose; ethyl acetate fraction was effective in all tested doses. Results for nitrite/nitrate levels reveals that only the ethyl acetate fraction was effective at the tested doses. This is the first report of the presence of isoquercetin, galangin and apigenin in this species. Results from the phytochemical analysis enhance the chemical knowledge of this species. In the future, together with more studies, validation of its popular use in inflammatory diseases is possible.

Myricitrin as the main constituent of two species of Myrcia.

Myricitrin was isolated as the major constituent from Myrcia splendens (2 g %) and Myrcia palustris (0.5g %) of their fractions soluble in ethyl acetate. The presence of this compound was confirmed by chromatographic analyses using HPLC-DAD. The antioxidant activity was measured using reducing power in relation to the reduction of iron (III) to iron (II) ions and DPPH radical scavenging assay. The ethyl acetate and butanol fractions showed the highest antioxidant activity for both species. In relation to the ability of the sample to scavenge DPPH radicals the EC50 values were 8.44 and 9.35 μg/ mL for M. splendens and 17.83 and 15.34 μg/ mL for M. palustris for the ethyl acetate and butanol fractions, respectively. The antioxidant activity may be related to the myricitrin in these extracts that showed an EC50 = 13.93 μg/mL.