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Flavonoids are a class of natural polyphenolic compounds which cannot be synthesized by humans. These substances possess a series of biological properties, acting on biological systems as antioxidants. The purpose of this study was to analyze the properties of certain foods, determining the total flavonoids as well as their antioxidant activity and fat concentration. We evaluated several foods purchased at the local market, with respect to its antioxidant activity, using two experimental models, the discoloration of DPPH˙ radical and ABTS −. Some foods such as pitanga showed antioxidant activity. The lipid content of fatty foods like açaí, cacao and cupuaçú was determined. Other foods, including pitanga, açaí, cacao and cupuaçú, were evaluated for flavonoid content and antioxidant activity using multivariate statistical analysis (PCA) as a statistical tool to evaluate the correlation between these two parameters. As samples with ED50 up to 500 µg/mL show promising antioxidant activity, several Brazilian fruit and vegetables could be consumed to this end, with a good correlation between flavonoid content and antioxidant activity in most samples. The daily dose of different types of food for antioxidant activity has been calculated based on these results.

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Early and reliable diagnosis of melanoma, a skin tumor with a poor prognosis, is extremely important. Phage display peptide libraries are a convenient screening resource for identifying bioactive peptides that interact with cancer targets. The aim of this study was to evaluate two technetium-99m tracers for angiogenesis detection in a melanoma model, using cyclic pegylated pentapeptide with RGD and NGR motifs conjugated with the bifunctional chelator mercaptoacetyltriglycine (MAG(3)). The conjugated peptides (10 μl of a μg/μl solution) were labeled with technetium-99m using a sodium tartrate buffer. Radiochemical evaluation was carried out by instant thin-layer chromatography and confirmed by high-performance liquid chromatography. The partition coefficient was determined and internalization assays were performed in two melanoma cell lines (B16F10 and SKMEL28). Biodistribution evaluation of the tracers was carried out in healthy animals at different time points and also in tumor-bearing mice, 120 min post injection. Blocking studies were also conducted by coinjection of cold peptides. The conjugates displayed a rather similar pharmacokinetic profile. They were radiolabeled with high radiochemical purity (>97%) and both were hydrophilic with preferential renal excretion. Yet, tumor uptake was higher for human than for murine melanoma cells, especially for [(99m)Tc]-MAG(3)-PEG(8)-c(RGDyk) (7.85±2.34%injected dose/g 120 min post injection). The performance of [(99m)Tc]-MAG(3)-PEG(8)-c(RGDyk) was better than the NGR tracer with regard to human melanoma uptake. In this sense, it should be considered for future radiotracer studies of tumor diagnosis.

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