Aplicación de la química analítica en el estudio de metales en alimentos

En la actualidad ha surgido interés en la calidad de los alimentos que consume el hombre, por lo que, es importante determinar contaminantes en alimentos. En este trabajo se analiza la presencia de metales en vegetales que son cultivados en las Chinampas de Xochimilco; estos son regados con aguas tratadas y residuales procedentes de descargas industriales y municipales. Es probable que exista contaminación por metales tóxicos (Galán y Romero 2008) para el hombre, como son: Cr, Pb y Cu. La Unión Europea propone como límite máximo de plomo en hortalizas de 0.1 a 0.3 ppm, el cromo con un límite de 0.1 ppm para cualquier alimento y el cobre de 10 ppm. En este trabajo se analizaron hojas de espinaca, betabel y brócoli, los cuales tiene un contenido de plomo de 0.5, 0.291 y 0.258 ppm respectivamente; cromo en hoja de espinaca 0.365 ppm, en betabel 0.249 ppm, en brócoli no se detectan cantidades apreciables de este metal; el cobre para estas hortalizas está dentro del límite permitido por la Unión Europea (Unión Europea 2014). Para respaldar los resultados obtenidos se realizó un análisis estadístico para la determinación de sensibilidad, límite de detección, límite de cuantificación para cada uno de los metales analizados por espectroscopía de absorción atómica.Nowadays there is a great concern about the quality of the food consumed by man. Hence the importance of identifying the contaminants in food. In this investigation project the presence of metals in vegetables that are cultivated in the chinampas of Xochimilco is analyzed. These crops are irrigated with treated water that comes from industrial and municipal discharges. It is likely that there might be contamination of toxic metals such as Cr, Pb and Cu. The European Union proposes 0.1 to 0.3 ppm as the maximum limit of Lead in crops. Chromium has a limit of 0.1 ppm for any food, whereas Copper limit is 10 ppm. In this investigation spinach, beetroot and broccoli leaves were analyzed. The Lead content of the samples was 0.5, 0.291 and 0.258 ppm respectively. Chromium in spinach leaves was 0.365 ppm, while in beetroot was 0.249 ppm. However, in broccoli no appreciable amounts of this metal were detected. Copper in these crops is within the limit allowed by the European Union. In order to support the results obtained, a statistical analysis for the determination of sensibility, detection limit and quantification limit was carried out for every metal that was analyzed using atomic absorption spectroscopy

Bis- y tris-smetilisotioureas derivadas del benzotiazol

En esta investigación reportamos algunos avances sobre la síntesis de compuestos bis- y trisisotioureas derivadas del benzotiazol. El procedimiento es por el uso de dos o tres equivalentes molares del intermediario ditiometilcarboimidatobenzotiazol por reacción con un equivalente molar de di- o triaminas aromáticas y alifáticas en reflujo de etanol. La reacción procede por ataque nucleofílico de las aminas sobre el grupo carboimidato, provocando el desplazamiento de moléculas de HSMe. Las isotioureas obtenidas aún contienen un grupo S-Me, lo que permite explorar una segunda sustitución con aminas alifáticas y anilina para conducir a las correspondientes bis- o tris-guanidinas. Las estructuras de los compuestos se asignaron por Resonancia Magnética Nuclear de ¹H y ¹³C. Se logró sintetizar un compuesto mixto que contiene el grupo isotiourea y guanidino, cuya estructura se determinó por difracción de rayos-X.In this investigation, we report some advances on the synthesis of bis- and tris benzothiazolisothioureas derived from 2-aminobenzothiazole, when two or three molar equivalents ofdithiomethylcarboimidatebenzothiazole as intermediate with one molar equivalent of aliphatic and aromatic di- or three-amines in refluxing de ethanol. The reaction proceeds by nucleophylic attack of the amines on the carboimidate group to force the leave of a HSMe molecule. The SMe group of the obtained isothioureas can be leave with a second mol of amine to get the corresponding bis- or trisguanidines. The structures of compounds were assigned by ¹H and ¹³C Nuclear Magnetic Resonance. One compound that contains guanidine and isothiourea groups was synthetized and its structure studied by X-ray diffraction analysis

In Silico and In Vitro Studies of Benzothiazole-Isothioureas Derivatives as a Multitarget Compound for Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder. Inhibiting acetylcholinesterase (AChE), amyloid beta (Aβ1-42) aggregation and avoiding the oxidative stress could prevent the progression of AD. Benzothiazole groups have shown neuroprotective activity whereas isothioureas groups act as AChE inhibitors and antioxidants. Therefore, 22 benzothiazole-isothiourea derivatives (3a–v) were evaluated by docking simulations as inhibitors of AChE and Aβ1-42 aggregation. In silico studies showed that 3f, 3r and 3t had a delta G (ΔG) value better than curcumin and galantamine on Aβ1-42 and AChE, respectively. The physicochemical and pharmacokinetics predictions showed that only 3t does not violate Lipinski’s rule of five, though it has moderated cytotoxicity activity. Then, 3f, 3r and 3t were synthetized and chemically characterized for their in vitro evaluation including their antioxidant activity and their cytotoxicity in PC12 cells. 3r was able to inhibit AChE, avoid Aβ1-42 aggregation and exhibit antioxidant activity; nevertheless, it showed cytotoxic against PC12 cells. Compound 3t showed the best anti-Aβ1-42 aggregation and inhibitory AChE activity and, despite that predictor, showed that it could be cytotoxic; in vitro with PC12 cell was negative. Therefore, 3t could be employed as a scaffold to develop new molecules with multitarget activity for AD and, due to physicochemical and pharmacokinetics predictions, it could be administered in vivo using liposomes due to is not able to cross the BBB

Myeloperoxidase Inhibitory and Antioxidant Activities of (E)-2-Hydroxy-α-aminocinnamic Acids Obtained through Microwave-Assisted Synthesis

Myeloperoxidase (MPO) is an enzyme present in human neutrophils, whose main role is to provide defenses against invading pathogens. However, highly reactive oxygen species (ROS), such as HOCl, are generated from MPO activity, leading to chronic diseases. Herein, we report the microwave-assisted synthesis of a new series of stable (E)-(2-hydroxy)-α-aminocinnamic acids, in good yields, which are structurally analogous to the natural products (Z)-2-hydroxycinnamic acids. The radical scavenging activity (RSA), MPO inhibitory activity and cytotoxicity of the reported compounds were evaluated. The hydroxy derivatives showed the most potent RSA, reducing the presence of DPPH and ABTS radicals by 77% at 0.32 mM and 100% at 0.04 mM, respectively. Their mechanism of action was modeled with BDEOH, IP and ΔEH-L theoretical calculations at the B3LYP/6 − 31 + G(d,p) level. Compounds showed in vitro inhibitory activity of MPO with IC50 values comparable to indomethacin and 5-ASA, but cytotoxicities below 15% at 100–200 µM. Docking calculations revealed that they reach the amino acid residues present in the distal cavity of the MPO active site, where both the amino and carboxylic acid groups of the α-aminopropenoic acid arm are structural requirements for anchoring. (E)-2-hydroxy-α-aminocinnamic acids have been synthesized for the first time with a reliable method and their antioxidant properties demonstrated