Propolis has been the subject of several recent studies, with the aim of elucidating its biological and pharmacological properties. Propolis has a well-known antimicrobial activity as well as antioxidant, antitumoral, antiinflammatory, and regenerative properties, but literature about its effects on the immune response is scarce. The goal of this work was to evaluate the propolis effect on macrophage activation by oxygen (H2O2) and nitrogen (NO) metabolite determination. Propolis was produced by africanized honeybees and hydroalcoholic solutions were prepared at different concentrations. Peritoneal macrophages were obtained from male BALB/c mice and culture cells were stimulated in vitro with propolis or interferon-gamma (IFN-gamma). In the in vivo assay, the animals were sacrificed after propolis treatment and cells were stimulated with IFN-gamma. We also investigated the co-stimulant action of propolis associated with IFN-gamma on macrophages. The results show that propolis induces a discreet elevation in H2O2 release and a mild inhibition of NO generation, depending on concentration. Propolis had no co-stimulant activity, diminishing IFN-gamma action on H2O2 and NO production. Data suggest that propolis acts on host non-specific immunity by macrophage activation

We report on the degenerate two-photon absorption (2PA) spectra of perylene tetracarboxylic derivatives (PTCDs), bis-(benzimidazo)perylene (AzoPTCD), and bis(benzimidazo)-thioperylene (Monothio BZP), obtained by means of the Z-scan technique with femtosecond laser pulses. The results show that these materials possess exceptionally high 2PA cross-sections. At 750 nm, for instance, AzoPTCD and Monothio BZP present 2PA cross-sections of 3400 10 ±50 cm 4 s photon ±1 and 1170 10 ±50 cm 4 s photon ±1, respectively. In addition, the 2PA saturation behavior observed as the laser irradiance increases and the strong two-photon-induced fluorescence suggest that PTCD compounds may be attractive candidates for applications in optical limiting and two-photon pumped (2PP) upconversion lasing.Upon exposure to intense laser pulses, molecules can instantaneously absorb two photons to access an excited state, each of them with half of the energy required to match the electronic transition. Such a 2PA process has interesting characteristics with direct consequences to applications including: i) improved spatial resolution owing to the square dependence on the excitation irradiance; ii) negligible linear absorption at the pumping wavelength, with a resulting increase of penetration depth, particularly in biological tissues; and iii) very fast temporal response. The advantages of the 2PA mechanism have been explored in numerous studies leading to promising applications, such as 2PP frequencyupconverted lasing, optical limiting, fluorescence excitation microscopy and imaging, three-dimensional optical data storage and lithographic microfabrication, and photodynamic therapy.[1±8] Accordingly, a great deal of effort has been directed to the development of various design strategies to synthesize new two-photon absorbing materials with large 2PA cross-sections (d) and to increase physical and chemical stabilities. Most of the recently developed two-photon absorbers are organic compounds. [2,5,9±15] Here, we investigate the possibility of using PTCD dyes as materials with high nonlinear optical absorption. PTCDs are organic dyes, readily available and thermally and chemically stable. The perylene moiety presents remarkable electron-donor characteristics, [16,17] although on adding lateral groups, the molecule can play either an electron-acceptor or -donor role. Moreover, their strong absorption and emission in the visible spectral range makes them potential candidates for applications as organic semiconductors, photoconductors, and laser materials.[16±22]Although high optical nonlinearities have been reported in organic materials at specific wavelengths, only recently has the dispersion of the nonlinear absorption over a wide spectral range begun to be characterized. [2,5,7,13±15,23±26] From an applications point of view, such information is important in formulating a molecular design strategy for a given nonlinear optical material. In this context, the present work reports on the degenerate 2PA cross-section spectra of AzoPTCD and Monot...

No abstract