Abstract
This work describes the isolation and structural elucidation of compounds from the leaves of Myrcia tomentosa (Aubl.) DC. (goiaba-brava) and evaluates the antimicrobial activity of the crude extract, fractions and isolated compounds against bacteria and fungi. Column chromatography was used to fractionate and purify the extract of the M. tomentosa leaves and the chemical structures of the compounds were determined using spectroscopic techniques. The antibacterial and antifungal activities were assessed using the broth microdilution method. The phytochemical investigation isolated 11 compounds: α-bisabolol, α-bisabolol oxide B, α-cadinol, β-sitosterol, n-pentacosane, n-tetracosane, quercetin, kaempferol, avicularin, juglanin and guaijaverin. The crude ethanolic extract and its fractions were tested against 15 bacteria and 9 yeasts. The crude extract inhibited the in vitro growth of yeasts at concentration of 4 to 32 μg/mL. The hexane, dichloromethane, ethyl acetate and aqueous fractions inhibited Candida sp. at concentrations of 4 to 256 μg/mL, whereas the Cryptococcus sp. isolates were inhibited only by the hexane and dichloromethane fractions in minimal inhibitory concentrations (MICs) at 16 to 64 μg/mL. The flavonoid quercetin-3-O-α-arabinofuranose (avicularin) was the most active compound, inhibiting Candida species in concentrations of 2 to 32 μg/mL. The MIC values suggest potential activity of this plant species against yeast.
Highlights
Infectious diseases are of great interest in the scientific community because some microorganisms cause severe morbidity and can be lethal
These activities often tofirst the bioassay-guided isolation of the extract and structural elucidation of the compounds, so as to verify the presence of secondary metabolites, such as their essential oils, but with few properties related to their antimicrobial activity of these extracts and compounds against certain bacterial and fungal pathogens
These results suggest that these sesquiterpenes partially contributed to the antifungal activity of this fraction, and that other compounds are necessary for the fractions to exhibit good activity
Summary
Infectious diseases are of great interest in the scientific community because some microorganisms cause severe morbidity and can be lethal. M. tomentosa is underreported in pharmacognostic or phytochemical studies Several biological metabolites, their essential oils, but with fewsuch properties related to their non-volatile activities havesuch been as described for the species of this genus, as the inhibition of thyroid peroxidase, compounds [6]. M. tomentosa, the aim of this are work is toattributed realize the anti-nociceptive andscarcity hepatoprotective activities [11,12,13,14,15,16,17] These activities often tofirst the bioassay-guided isolation of the extract and structural elucidation of the compounds, so as to verify the presence of secondary metabolites, such as their essential oils, but with few properties related to their antimicrobial activity of these extracts and compounds against certain bacterial and fungal pathogens. (NMR) data with 2D experiments Heteronuclear Single Quantum Coherence (HSQC) and
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