Eugenia Pohliana Leaves Essential Oil Inhibits Fungal Virulence and Restores Antibiotic Efficacy in Multidrug-Resistant Bacterial Strains.

This study aims to investigate the essential oil from leaves of Eugenia pohliana (EOEP) in regard to its chemical composition, antimicrobial and drug-enhancing activity, as well as the reduction of fungal virulence capacity. Chemical characterization using GC-MS showed as major components the sesquiterpenes δ-cadinene, Epi-α-Muurolol, and bicyclogermacrene. The results of antibacterial tests indicated that Staphylococcus aureus was more sensitive to EOEP, that also enhanced the efficacy of gentamicin, erythromycin, and norfloxacin. EOEP exhibited antifungal properties against Candida albicans, in addition to potentiating the effectiveness of fluconazole against Candida tropicalis. It showed anti-virulence effects in all fungal strains. These findings underscore E. pohliana as a potential candidate for the prospection of novel therapeutic agents to treat infectious diseases caused by resistant microbes.

Evaluation of 28-day repeated doses oral toxicity of essential oil from Psidium glaziovianum Kiaersk leaves on various biological parameters in Swiss mice.

Only a small number of the many medicinally important species in the genus Psidium L. have had their safety assessed. Psidium glaziovianum, a plant native to Brazil, is reported to exert antinociceptive and anti-inflammatory effects; however, there are no apparent reports of long-term safety following administering of repeated doses. The aim of this study was to examine the effects of 28-day oral of treatment at 250, 500 or 1,000 mg/kg Psidium glaziovianum essential oil (PgEO) on behavioral and physiological parameters in male and female Swiss mice. First, PgEO was chemically characterized by gas chromatography mass spectrometry (GC-MS). The following parameters were examined: motor activity, body temperature, blood glucose, urine, hematology, biochemistry, histology, and oxidative stress. Characterization of PgEO revealed 48 components which were dominated by sesquiterpenes 1,8-cineol (24.29%), α-pinene (19.73%) and ß-pinene (17.31%). Data showed that PgEO treatment in mice increased activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) without markedly affecting body weight, hematological or biochemical parameters, as well as water or food consumption. Administration of PgEO in repeated daily dosages over 28 days did not significantly alter exploratory or locomotor activities. Based upon our findings, PgEO administration daily for 28 days, exhibited low toxicity and absence of effects on the nervous system. Data demonstrated that PgEO produced hypoglycemic and antioxidant actions which need to be considered in safety assessment.

Bioguided Purification of Active Compounds from Leaves of Anadenanthera colubrina var. cebil (Griseb.) Altschul.

Anadenanthera colubrina var cebil (Griseb.) Altschul is a medicinal plant found throughout the Brazilian semi-arid area. This work performed a bioguided purification of active substances present in ethyl acetate extract from A. colubrina leaves. The anti-Staphylococcus aureus and antioxidant actions were used as markers of bioactivity. The extract was subjected to flash chromatography resulting in five fractions (F1, F2, F3, F4, and F5). The fractions F2 and F4 presented the highest antimicrobial action, with a dose able to inhibit 50% of bacteria growth (IN50) of 19.53 µg/mL for S. aureus UFPEDA 02; whereas F4 showed higher inhibitory action towards DPPH radical (2,2-diphenyl-1-picryl-hydrazyl-hydrate) [dose able to inhibit 50% of the radical (IC50) = 133 ± 9 µg/mL]. F2 and F4 were then subjected to preparative high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR), resulting in the identification of p-hydroxybenzoic acid and hyperoside as the major compounds in F2 and F4, respectively. Hyperoside and p-hydroxybenzoic acid presented IN50 values of 250 µg/mL and 500 µg/mL against S. aureus UFPEDA 02, respectively. However, the hyperoside had an IN50 of 62.5 µg/mL against S. aureus UFPEDA 705, a clinical isolate with multidrug resistant phenotype. Among the purified compounds, the proanthocyanidins obtained from F2 exhibited the higher antioxidant potentials. Taken together, these results highlight the potential of A. colubrina leaves as an alternative source of biomolecules of interest for the pharmaceutical, food, and cosmetic industries.

Anti-staphylococcal activity of Syagrus coronata essential oil: Biofilm eradication and in vivo action on Galleria mellonela infection model.

In this study, essential oil extracted from Syagrus coronata seeds (SCEO) was evaluated for antibacterial and antibiofilm activities against Staphylococcus aureus; in addition, Galleria mellonella model was used as an in vivo infection model. SCEO was mainly composed by fatty acids (89.79%) and sesquiterpenes (8.5%). The major components were octanoic acid, dodecanoic acid, decanoic acid and γ-eudesmol. SCEO showed bactericidal activity (minimal bactericidal concentration from 312 to 1250 µg/mL) against all tested S. aureus clinical isolates, which showed distinct biofilm-forming and multiple drug resistance phenotypes. SCEO weakly reduced biomass but remarkably decreased cell viability in pre-formed biofilms of S. aureus isolate UFPEDA-02 (ATCC-6538). Electron microscopy analysis showed that SCEO treatments decreased the number of bacterial cells (causing structural alterations) and lead to loss of the roughness in the multiple layers of the three-dimensional biofilm structure. In addition, overproduction of exopolymeric matrix was observed. SCEO at 31.2 mg/kg improved the survival of G. mellonela larvae inoculated with UFPEDA-02 isolate and reduced the bacterial load in hemolymph and melanization. In conclusion, SCEO is an antibacterial agent against S. aureus strains with different resistance phenotypes and able to disturb biofilm architecture. Our results show SCEO as a potential candidate to drug development.