Antonio Ivanildo Pinho

Eugenia uniflora leaves essential oil induces toxicity in Drosophila melanogaster: involvement of oxidative stress mechanisms

Eugenia uniflora L. (Myrtaceae family), also known as “pitanga”, is a tree species widely used in popular medicine. Despite the well documented beneficial effects of the extracts and essential oils from this plant, little is known about its toxicity. We performed a phytochemical fingerprinting and evaluated the toxicity induced by the Eugenia uniflora leaves essential oil in a Drosophila melanogaster model. In order to understand the biochemical mechanisms involved in E. uniflora essential oil toxicity, changes in the Nrf2 signaling as well as the hallmarks of oxidative stress were measured. The exposure of adult flies to the essential oil via a fumigant method resulted in increased mortality and locomotor deficits. In parallel, an oxidative stress response signaling, evidenced by changes in ROS production, lipid peroxidation, alterations in the activity of antioxidant enzymes and expression of Nrf2 protein targets occurred. In the light of our findings, attention is drawn to the indiscriminate use of this plant for medicinal purposes. In addition, a potential bio-insecticidal activity of Eugenia uniflora volatile compounds is suggested, a fact that needs to be further explored.

Antioxidant and mercury chelating activity of Psidium guajava var. pomifera L. leaves hydroalcoholic extract

ABSTRACT Mercury (Hg) is widely distributed in the environment and is known to produce several adverse effects in organisms. The aim of the present study was to examine the in vitro antioxidant activity and Hg chelating ability of the hydroalcoholic extract of Psidium guajava leaves (HEPG). In addition, the potential protective effects of HEPG against Hg(II) were evaluated using a yeast model (Saccharomyces cerevisiae). HEPG was found to exert significant antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl scavenger and inhibition of lipid peroxidation induced by Fe(II) assays in a concentration-dependent manner. The extract also exhibited significant Hg(II) chelating activity. In yeast, Hg(II) induced a significant decrease in cell viability. In contrast, HEPG partially prevented the fall in cell viability induced by Hg(II). In conclusion, HEPG exhibited protective effects against Hg(II)-mediated toxicity, which may be related to both antioxidant and Hg(II)-chelating activities.

Fumigant activity of the Psidium guajava var. pomifera (Myrtaceae) essential oil in Drosophila melanogaster by means of oxidative stress.

The guava fruit, Psidium guajava var. pomifera (Myrtaceae family), is a native plant from South America. Its leaves and fruits are widely used in popular medicine in tropical and subtropical countries. Drosophila melanogaster has been used as one of the main model organisms in genetic studies since the 1900s. The extensive knowledge about this species makes it one of the most suitable organisms to study many aspects of toxic compound effects. Due to the lack of studies on the effects of the bioactive compounds present in the P. guajava var. pomifera essential oil, we performed a phytochemical characterization by CG-MS and evaluated the toxicity induced by the essential oil in the D. melanogaster insect model. In order to understand the biochemical mechanisms of toxicity, changes on the Nrf2 signaling as well as hallmarks of oxidative stress response were followed in the exposed flies. Our results showed that exposure of insects to the P. guajava oil increased mortality and locomotor deficits in parallel with an oxidative stress response signaling. Therefore, it suggested a bioinsecticidal activity for P. guajava volatile compounds by means of oxidative stress. Further studies are ongoing to identify which oil compounds are responsible for such effect.

Antibiotic-Modifying Activity and Chemical Profile of the Essential Oil from the Leaves of Cordia verbenacea DC.

Abstract This study aimed to determine the chemical profile of the essential oil obtained from the leaves of C. verbenacea DC and to evaluate its antibiotic and antibiotic-modifying activity by the gaseous contact method of the essential oil and its major component. The essential oil was analyzed by GC-MS. Chemical analysis identified a predominance of sabinene (31.99%), β-caryophyllene (13.10%), bicyclogermacrene (11.06%), germacrene-D (7.44%) and (+) spathulenol (6.53%). The essential oil and sabinene exhibited no antibacterial activity according to the method used. Sabinene combined with all antibiotics showed synergism against S. aureus and the essential oil showed indifference when combined with aminoglycosides. We demonstrated that sabinene has statistically significant antibiotic-modifying activity against S. aureus, indicating this compound as a new alternative pharmaceutical source in fighting infections by Gram-positive bacteria.