Polymeric nanoparticles (PLGA) have been developed for the encapsulation and controlled release of quercetin and catechin. Nanoparticles were fabricated using a solvent displacement method. Physicochemical properties were measured by light scattering, scanning electron microscopy andζ-potential, X-ray diffraction, infrared spectroscopy and differential scanning calorimetry. Encapsulation efficiency andin vitrorelease profiles were obtained from differential pulse voltammetry experiments. Antioxidant properties of free and encapsulated flavonoids were determined by TBARS, fluorescence spectroscopy and standard chelating activity methods. Relatively small (d≈ 400 nm) polymeric nanoparticles were obtained containing quercetin or catechin in a non-crystalline form (EE≈79%) and the main interactions between the polymer and each flavonoid were found to consist of hydrogen bonds.In vitrorelease profiles were pH-dependant, the more acidic pH, the faster release of each flavonoid from the polymeric nanoparticles. The inhibition of the action of free radicals and chelating properties, were also enhanced when quercetin and catechin were encapsulated within PLGA nanoparticles. The information obtained from this study will facilitate the design and fabrication of polymeric nanoparticles as possible oral delivery systems for encapsulation, protection and controlled release of flavonoids aimed to prevent oxidative stress in human body or food products.

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In order to identify pigmented corn with nutraceutical potential, the secondary metabolite content, the antioxidant capacity and antimutagenic activity of red, and blue corn were analyzed. The ranges of total phenolic, flavonoid and anthocyanin contents of the corn samples were from 69.4 to 212.8 mg gallic ac. equiv./100 g DW, 0.07 to 12.19 mg (?) catechin eq./100 g DW and 3.89 to 34.17 mg cyanidin-3-O-glucoside eq./100 g DW, respectively. The phenolic extracts demonstrated the highest antioxidant capacity evaluated by the ABTS assay displaying values from 2.06 to 7.34 mmol Trolox/100 g DW. None of the extracts was toxic to the tested bacteria strains TA98 and TA100. For TA98 tester strain, percentage inhibition values against AFB 1 mutagenicity from 61 to 93, and 38 to 75 for flavonoid and anthocyanin extracts were obtained. The total phenol and anthocyanin contents correlate with the observed antioxidant capacity. The most biological active corn samples were the blue color while the least actives were the red ones. The results show that the studied blue corn samples are good sources of antioxidant and antimutagenic compounds, which could use to develop products that contribute to human health.

Mexico has the highest per capita consumption of corn in the world, which is consumed mainly as tortilla. However, only a few in vivo studies have demonstrated the anticarcinogenic potential of some maize components against colon cancer, but not as a whole food product. Therefore, our objective was to evaluate the protective effect of corn tortillas against the development of colon cancer. First, blue, red, yellow and white corn grains were lime-cooked and processed to elaborate tortillas. Then, tortillas were administered into the diet (27% w/w) to male Sprague-Dawley rats induced with the colon carcinogen 1,2-dimethylhydrazine (DMH). Our results indicated that consumption of tortillas, particularly from white and blue corns, significantly decreased adenocarcinoma incidence (up to 77.5%) and mean number compared to DMH-treated animals. In addition, an inhibition of β-glucuronidase activity, and induction of detoxifying enzymes in liver and colon, as well as a decrease in the expression of the two most important proliferative proteins (K-ras and β-catenin) involved in colon carcinogenesis, were also observed. These results highlight some of the molecular mechanisms related to the chemopreventive effect of tortillas, thus indicating that corn products retain their biological properties even after nixtamalization and tortilla processing.