Browsing by Subject "Chitin"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Publication
    Open Access
    An infrared investigation in relation with chitin and chitosan characterization
    (Elsevier, 2001-01-12) Brugnerotto, J.; Lizardi, J.; Goycoolea Valencia, Francisco Martín; Argüelles Monal, Waldo; Desbrières, J.; Rinaudo, Marguerite; Biología Celular e Histología
    The use of infrared spectroscopy for characterization of the composition of chitin and chitosan covering the entire range of degree of acetylation (DA) and a wide variety of raw materials is examined further. The ratio of absorbance bands selected was calibrated using 1H liquid and 13C CP-MAS solid-state NMR as absolute techniques. IR spectra of the structural units of these polymers validated the choice of baselines and characteristic bands. The bands at 1650 and 1320 cm-1 were chosen to measure the DA. As internal reference, the intensities at 3450 and 1420 cm-1 were evaluated. The absorption band ratios involving the reference at 3450 cm-1 had poorer fit. The absorption ratio A1320/A1420 shows superior agreement between the absolute and estimated DA-values (DA% = 31.92A1320/A1420 - 12.20; r = 0.990)
  • Thumbnail Image
    Publication
    Open Access
    Determination of Chitin and protein contents during the isolation of Chitin from shrimp waste
    (Wiley, 2006-05-09) Díaz Rojas, Erika I.; Argüelles Monal, Waldo M.; Higuera Ciapara, Inocencio; Hernández, Javier; Lizardi Mendoza, Jaime; Goycoolea Valencia, Francisco Martín; Biología Celular e Histología
    Accurate determination of chitin and protein contents in crustacean biomass and the intermediate products during the industrial isolation of chitin cannot be made directly from the total nitrogen content, unless the appropriate corrections are applied. This method, however, is affected by the presence of other nitrogen-containing chemical species that are formed endogenously or by the action of microorganisms during the handling of the sample. Therefore, an alternative rapid method to estimate the contents of these components can be very useful both in research and in various fields of application. An original method has been developed to address this problem. The method consists of the development of a set of equations based on the stoichiometric contents of nitrogen of chitin and protein whereby the amounts of each component can be estimated from the value of the total nitrogen content, provided the rest of the proximate composition of the sample is accurately known. In order to validate the procedure, a set of model mixtures of pure chitin and protein concentrate in the solid state, both extracted from shrimp head waste, are used. Excellent agreement between the predicted and real values of chitin and protein are obtained (R2=0.98, slope=0.90). When the proposed method is tested in the analysis of real samples obtained from five different processing protocols of pretreatment of raw shrimp head, it is found that in general, the values of protein and chitin contents throughout the various stages of the process vary as expected.
  • Repository logo
    Publication
    Restricted
    Micafungin enhances the human macrophage response to Candida albicans through β-glucan exposure
    (American Society for Microbiology, 2018-04-26) Martínez-Esparza, M.; Guirao-Abad, José Pedro; Sánchez-Fresneda, Ruth; Machado, Francisco; Argüelles, Juan Carlos; Bioquímica y Biología Molecular B e Inmunología
    Micafungin belongs to the antifungal family of echinocandins, which act as noncompetitive inhibitors of the fungal cell wall β-1,3-d-glucan synthase. Since Candida albicans is the most prevalent pathogenic fungus in humans, we study the involvement of micafungin in the modulation of the inflammatory response developed by human tissue macrophages against C. albicans The MIC for micafungin was 0.016 μg/ml on the C. albicans SC5314 standard strain. Micafungin induced a drastic reduction in the number of exponential SC5314 viable cells, with the fungicidal effect being dependent on the cellular metabolic activity. Notably, micafungin also caused a structural remodelling of the cell wall, leading to exposure of the β-glucan and chitin content on the external surface. At the higher doses used (0.05 μg/ml), the antifungal also induced the blowing up of budding yeasts. In addition, preincubation with micafungin before exposure to human tissue macrophages enhanced the secretion of tumor necrosis factor alpha (TNF-α), interleukin-17A (IL-17A), and IL-10 cytokines. Our results strongly suggest that in C. albicans treatment with micafungin, in addition to having the expected toxic antifungal effect, it potentiates the immune response, improving the interaction and activation of human macrophages, probably through the unmasking of β-glucans on the cell wall surface.