EGCG-like non-competitive inhibitor of DYRK1A rescues cognitive defect in a down syndrome model.

Overexpression of the chromosome 21 DYRK1A gene induces morphological defects and cognitive impairments in individuals with Down syndrome (DS) and in DS mice models. Aging neurons of specific brain regions of patients with Alzheimer's disease, DS and Pick's disease have increased DYRK1A immunoreactivity suggesting a possible association of DYRK1A with neurofibrillary tangle pathology. Epigallocatechin-3-gallate (EGCG) displays appreciable inhibition of DYRK1A activity and, contrary to all other published inhibitors, EGCG is a non-competitive inhibitor of DYRK1A. Prenatal exposure to green tea polyphenols containing EGCG protects from brain defects induced by overexpression of DYRK1A. In order to produce more robust and possibly more active analogues of the natural compound EGCG, here we synthetized new EGCG-like molecules with several structural modifications to the EGCG skeleton. We replaced the ester boun of EGCG with a more resistant amide bond. We also replaced the oxygen ring by a methylene group. And finally, we positioned a nitrogen atom within this ring. The selected compound was shown to maintain the non-competitive property of EGCG and to correct biochemical and behavioral defects present in a DS mouse model. In addition it showed high stability and specificity.

Methodology for porphyrin isolation by high-performance countercurrent chromatography.

Countercurrent chromatography is a versatile technique for the isolation of a wide variety of plant substances. However, little attention has been devoted to the application of this technique for the isolation of porphyrins. This class of compounds are of great importance in the medical area and in photocatalysis due to their heterocyclic structure, composed of four modified pyrrol subunits interconnected on their a carbon atoms by methinic bridges. The methanol extract of Gallesia integrifolia was partitioned using different solvents; the dichloromethane fraction was then submitted to countercurrent chromatography. The solvent system composed of n-hexane, ethyl acetate, methanol, and water (1:2.5:2.5:1) was chosen to perform the chromatographic analysis due to the enhanced solubility and the best distribution coefficients of the target compounds. Two porphyrins were isolated by this method and identified as 13(2)-hydroxypheophorbide a methyl ester and pheophorbide a, methyl ester. The solvent system proposed provided good distribution coefficients for both substances (1.27 and 1.87, respectively), and a high resolution factor.

[Study of the effect of thiosemicarbazones against Toxoplasma gondii]. / Étude de l'effet des thiosemicarbazones sur Toxoplasma gondii.

Toxoplasmosis is a neglected disease, with an estimated occurrence of one-third of the population worldwide. Research in medicinal chemistry has for some years been pursuing the development of new drugs against toxoplasmosis, because current treatments cause serious side effects in the patient. The use of thiosemicarbazones as an alternative option for the treatment of various diseases has been published in recent years, due to their, among others, anticancer, antimalarial, antitrypanosomal, antibacterial, and antitoxoplasmosis activities, the latter being the subject of this study, which is based upon biological analyses and tests of the response of Toxoplasma gondii in the presence of thiosemicarbazones.