Agarose-silver particles films: Effect of calcium ascorbate in nanoparticles synthesis and film properties.

New nanoparticles containing biomaterials are emerging as versatile active platforms in a great number of applications, for example, as skin substitutes and therapeutic media. The present study describes the preparation of silver nanoparticles (AgNPs) embedded in agarose films and the impact of calcium ascorbate in the formation of ANPs as well as in the final properties of the films. Colloidal AgNPs were synthetized by two chemical reduction routes: (i) applying calcium ascorbate and NaBH4 and (ii) applying only NaBH4. AgNPs synthetized using NaBH4 showed sizes ranging from 5 to 18 nm while AgNPs were calcium ascorbate was used showed micrometer from 164 to 955 nm size. Films were prepared in three formulations: agarose control film (A1); agarose + AgNPs without calcium ascorbate (A2) and agarose + AgNPs with calcium ascorbate (A3). The characterization of films by SEM and EDS showed agarose agglomerates in A2 and unreacted calcium ascorbate crystals on surface of A3. Thus, the presence of calcium ascorbate influenced the properties of A3 film. In addition, the antimicrobial analysis showed a silver particles release dependence on the film composition and only the A3 presented activity against Staphylococcus aureus. The results found in this study open an important way for development of new biomaterials, economically competitive, and with medical application.

Evaluation of cytotoxic, immunomodulatory and antibacterial activities of aqueous extract from leaves of Conocarpus erectus Linnaeus (Combretaceae).

OBJECTIVES: This work evaluated the antibacterial activity, cytotoxicity and immunomodulatory effect on human peripheral blood mononuclear cells (PBMCs) promoted by aqueous extract from Conocarpus erectus leaves (AELCe). METHODS: The extract was characterized by thin layer chromatography and ultraperformance liquid chromatography coupled to mass spectrometry (UPLC-MS). Cytotoxicity of AELCe (6.25-50 µg/ml) was investigated using annexin V and propidium iodide. Cytokine and nitric oxide levels in PBMCs culture supernatants exposed or not to AELCe (12.5 µg/ml) were determined, and antibacterial activity was evaluated by disc diffusion and broth microdilution methods. KEY FINDINGS: AELCe contained 3',4'-OH flavonoids, phenylpropanoglycosides, saponins, polymeric proanthocyanidins and hydrolysable tannins. Moreover, 10 other compounds were identified through UPLC-MS technique. AELCe did not affect lymphocyte viability at 6.25 and 12.5 µg/ml. IL-2, IL-10, TNF-α, IFN-γ and nitric oxide was produced in higher levels by cells treated with AELCe. Proliferation and activation of CD8+ T lymphocytes were also stimulated. AELCe showed bacteriostatic activity against clinical and antibiotic-resistant strains of Staphylococcus aureus (MIC between 250 and 1000 µg/ml). CONCLUSIONS: AELCe showed a moderate bacteriostatic activity and promoted an immunomodulatory status through higher production of Th1 cytokines, nitric oxide release and T CD8+ lymphocytes stimulation.

Evaluation of embryotoxic and embryostatic effects of the aqueous extract of Rhizophora mangle and tannic acid on eggs and larvae of Aedes aegypti.

Rhizophora mangle is an abundant plant in mangroves and tannic acid is a polyphenol produced by the secondary metabolism of plants. The aim of the study was to evaluate the embryotoxic and embriostatic effects of the aqueous extract of R. mangle and synthetic tannic acid on eggs and larvae of Aedes aegypti. A. aegypti eggs were exposed in duplicate at concentrations of 250, 500, 750 and 1000 µg/mL of extract and tannic acid for a period of 14 days. Mineral water was used as a negative control. The eggs were observed and counted in a stereomicroscope (1.2x). In all extract concentrations there was stimulation in hatching in relation to the control, but only in concentration of 750 mg/mL it was statistically significant. In tannic acid (250µg/ml) there was significant stimulus in hatching, but in 500, 750 and 1000 µg/mL there was significant inhibition. All concentrations of aqueous extract and tannic acid on larvae showed embryotoxic and embryostatic effects when compared to the control. The aqueous extract of R. mangle showed effect on hatching of A. aegypti eggs and synthetic tannic acid showed embryotoxic and embryostatic effects. On larvae, both the aqueous extract as tannic acid showed embryotoxic and embryostatic effects.

Acute Toxicity and Cytotoxicity Effect of Ethanolic Extract of Spondias tuberosa Arruda Bark: Hematological, Biochemical and Histopathological Evaluation.

Spondias tuberosa Arruda, popularly named as umbu, is native from savanna-like vegetation and widely used for medicinal purposes, however, the toxicological profile is not available yet. This study evaluated the phytochemical profile and acute toxicity and citoxicity of Ethanolic Extract of Spondias tuberosa Arruda Bark (EEStb) in hematological, biochemical and histopathological parameters. Female Wistar rats were divided into: control (C) and animal treated single doses of 300mg/Kg (EEStb300) or 2.000mg/kg body weight (ESStb2.000) of the EEStb. After 24 hours and 14 days from gavage, the behavior, hematological, biochemical and histopathological parameters were assayed. Cytotoxicity effect was evaluated on HEp-2 cell lines. Neither EEStb300 nor EEStb2.000 produced mortality nor changes in body weight during the 14-days of observation, but EEStb2.000 reduced quietly the food and water intake as well as locomotor activity at first day. There were no changes in macroscopic, histopathological, biochemical and hematological parameters. EEStb in concentrations of 6.25- 50µg ml-1 on HEp-2 cell did not produce cytotoxic effect. These results suggest that EEStb did not cause acute toxicity and cytotoxic, suggesting a good safety rate for Spondias tuberosa Arruda.

Biological activity and photostability of biflorin micellar nanostructures.

Capraria biflora L. is a shrub from the Scrophulariaceae family which produces in its roots a compound named biflorin, an o-naphthoquinone that shows activity against Gram-positive bacteria and fungi and also presents antitumor and antimetastatic activities. However, biflorin is hydrophobic and photosensitive. These properties make its application difficult. In this work we prepared biflorin micellar nanostructures looking for a more effective vehiculation and better preservation of the biological activity. Biflorin was obtained, purified and characterized by UV-Vis, infrared (IR) and 1H- and 13C-NMR. Micellar nanostructures of biflorin were then assembled with Tween 80®, Tween 20® and saline (0.9%) and characterized by UV-Vis spectroscopy and dynamic light scattering (DLS). The results showed that the micellar nanostructures were stable and presented an average size of 8.3 nm. Biflorin micellar nanostructures' photodegradation was evaluated in comparison with biflorin in ethanol. Results showed that the biflorin in micellar nanostructures was better protected from light than biflorin dissolved in ethanol, and also indicated that biflorin in micelles were efficient against Gram-positive bacteria and yeast species. In conclusion, the results showed that the micellar nanostructures could ensure the maintenance of the biological activity of biflorin, conferring photoprotection. Moreover, biflorin vehiculation in aqueous media was improved, favoring its applicability in biological systems.

A bacterium belonging to the Burkholderia cepacia complex associated with Pleurotus ostreatus.

Pleurotus ostreatus is a widely cultivated white-rot fungus. Owing to its considerable enzymatic versatility P. ostreatus has become the focus of increasing attention for its possible utility in biobleaching and bioremediation applications. Interactions between microorganisms can be an important factor in those processes. In this study, we describe the presence of a bacterial species associated with P. ostreatus strain G2. This bacterial species grew slowly (approximately 30 days) in the liquid and semi-solid media tested. When P. ostreatus was inoculated in solid media containing Tween 80 or Tween 20, bacterial microcolonies were detected proximal to the fungal colonies, and the relevant bacterium was identified via the analysis of a partial 16S rDNA sequence; it was determined to belong to the Burkholderia cepacia complex, but was not closely related to other fungus-isolated Burkholderiaceae. New specific primers were designed, and confirmed the presence of in vitro P. ostreatus cultures. This is the first time that a bacterial species belonging to the B. cepacia complex has been found associated with P. ostreatus.