Antioxidant, Anti-inflammatory and Neuroprotective Profiles of Novel 1,4-Dihydropyridine Derivatives for the Treatment of Alzheimer's Disease

Alzheimer’s disease is a chronic and irreversible pathological process that has become the most prevalent neurodegenerative disease. Currently, it is considered a multifactorial disease where oxidative stress and chronic neuroinflammation play a crucial role in its onset and development. Its characteristic neuronal loss has been related to the formation of neurofibrillary tangles mainly composed by hyperphosphorylated tau protein. Hyperphosphorylation of tau protein is related to the over-activity of GSK-3β, a kinase that participates in several pathological mechanisms including neuroinflammation. Neuronal loss is also related to cytosolic Ca²⁺ homeostasis dysregulation that triggers apoptosis and free radicals production, contributing to oxidative damage and, finally, neuronal death. Under these premises, we have obtained a new family of 4,7-dihydro-2H-pyrazolo[3–b]pyridines as multitarget directed ligands showing potent antioxidant properties and able to scavenge both oxygen and nitrogen radical species, and also, with anti-inflammatory properties. Further characterization has demonstrated their capacity to inhibit GSK-3β and to block L-type voltage dependent calcium channels. Novel derivatives have also demonstrated an interesting neuroprotective profile on in vitro models of neurodegeneration. Finally, compound 4g revokes cellular death induced by tau hyperphosphorylation in hippocampal slices by blocking reactive oxygen species (ROS) production. In conclusion, the multitarget profile exhibited by these compounds is a novel therapeutic strategy of potential interest in the search of novel treatments for Alzheimer’s disease.

Aza-CGP37157-lipoic hybrids designed as novel Nrf2-inducers and antioxidants exert neuroprotection against oxidative stress and show neuroinflammation inhibitory properties

Two multitarget hybrids, derived from an aza-analogue of CGP37157, a mitochondrial Na⁺ /Ca²⁺ exchanger antagonist, and lipoic acid were designed in order to combine in a single molecule the antioxidant and Nrf2 induction properties of lipoic acid and the neuroprotective activity of CGP37157. The hybrid derivatives showed Nrf2 induction and radical scavenging properties, leading to a good neuroprotective profile against oxidative stress, together with an interesting antineuroinflammatory activity. The results obtained show differences in activity depending on the configuration of the chiral center of LA.

Discovery of the first dual GSK3β inhibitor/Nrf2 inducer. A new multitarget therapeutic strategy for Alzheimer's disease

The formation of neurofibrillary tangles (NFTs), oxidative stress and neuroinflammation have emerged as key targets for the treatment of Alzheimer’s disease (AD), the most prevalent neurodegenerative disorder. These pathological hallmarks are closely related to the over-activity of the enzyme GSK3β and the downregulation of the defense pathway Nrf2-EpRE observed in AD patients. Herein, we report the synthesis and pharmacological evaluation of a new family of multitarget 2,4-dihydropyrano[2,3-c]pyrazoles as dual GSK3β inhibitors and Nrf2 inducers. These compounds are able to inhibit GSK3β and induce the Nrf2 phase II antioxidant and anti-inflammatory pathway at micromolar concentrations, showing interesting structure-activity relationships. The association of both activities has resulted in a remarkable anti-inflammatory ability with an interesting neuroprotective profile on in vitro models of neuronal death induced by oxidative stress and energy depletion and AD. Furthermore, none of the compounds exhibited in vitro neurotoxicity or hepatotoxicity and hence they had improved safety profiles compared to the known electrophilic Nrf2 inducers. In conclusion, the combination of both activities in this family of multitarget compounds confers them a notable interest for the development of lead compounds for the treatment of AD.

RESULTADOS DE TESTES DE CULTURA E ANTIBIOGRAMA EM SEIS CASOS DE ÚLCERA CORNEANA EM EQUINOS

A ulceração corneana é uma desordemimportante nos olhos eqüinos, podendo levará cegueira se não tratada adequadamente. Esteestudo retrospectivo tem por objetivo mostrar a importânciado conhecimento da microbiota comensalde olhos eqüinos, para que, em caso de ulceraçãocorneana, o tratamento seja empregado de formarápida, enquanto aguardam-se resultados dos testesde cultura e antibiograma para possível ajuste na terapia.

Intramolecular Friedel-Crafts-type reactions involving N-acyliminium ions derived from glycine templates

Enantiomerically pure 4-substituted 2-aralkyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones (1b-m) in which the alkyl chain is (CH(2))(n), n = 1-3, behave as glycine templates giving by treatment with [hydroxy(tosyloxy)iodo]benzene in ethyl acetate cis-1-tosyloxy derivatives. When these compounds contain electron-rich aryl substituents with n = 2, they spontaneously cyclize through intramolecular Friedel-Crafts-type diastereoselective reactions to give penta- or hexacyclic compounds. Otherwise, they give by solvolysis cis-1-alkoxy derivatives, which in a second step, may be cyclized in acid if n = 2, 3. All these reactions must occur through N-acyliminium species in S(N)1-like mechanisms. 1-Alkoxy-2-arylmethyl derivatives are reluctant to cyclize, giving trans-1-hydroxy compounds as the only isolated reaction products.

Molecular bureaucracy: who controls the delays? Transient times in branched pathways and their control

Analysis of metabolic control has until now been mainly confined to systems at steady state. This includes studies of the control of "transition time", which is actually a steady-state transit time that does not refer to the transient state. In this paper we examine the control of the transition state of a metabolic pathway in the approach to a stable steady state, showing that the time needed to attain it can be decreased or increased in different branches. Our analysis only applies to branched pathways, and we discuss why similar deviations cannot occur in unbranched pathways. In systems with several branches the acceleration of some branches during the transient phase, so that they reach their steady states more quickly, occurs at the expense of others, which are thus delayed. We present theorems that describe properties of the transient variables and their control.

Synthesis and antitumour activity of fluorinated 1-aza and 1,8-diazaanthraquinones

A series of 3-fluoro-1-aza- and 1,8-diazaanthraquinones, structurally related to the antitumour antibiotic diazaquinomycin A, have been prepared by Diels-Alder reactions of 2-fluoro-2-propenal N, N-dimethylhydrazone and the corresponding quinones. These compounds showed potent in vitro activity against different tumour cell lines. They also showed some selectivity towards rapid-growth tumours when compared to other non-fluorinated analogues. In contrast with diazaquinomycin A, the azaanthraquinones studied here have not shown significant activity as thymidylate synthase inhibitors. Some compounds showed a high activity as inhibitors of protein, DNA and RNA biosynthesis.

Cerebrospinal fluid beta 2-microglobulin in neonates with central nervous system infections

Beta 2-microglobulin (beta 2m) determination in CSF of 72 neonates who underwent a spinal tap as part of a sepsis or meningo-encephalitis workup was performed to evaluate the usefulness of this test in the diagnosis of CNS infections. Beta 2m was measured by enzyme immunoassay. Sixty neonates had sterile culture and normal neurological status at discharge. Twelve infants had CNS infections: 8 bacterial meningitis, 3 TORCH infections (T = toxoplasmosis, O = others, R = rubella, C = cytomegalovirus and H = herpes simplex) and 1 viral meningitis. Neonates with CNS infection exhibited significantly higher CSF beta 2m levels compared to neonates with sterile culture (6.24 +/- 2.66 vs 1.74 +/- 0.5 mg/l; P < 0.0001). CSF beta 2m levels did not correlate with the white cell count, total protein concentration or glucose level in CSF. When serum and CSF levels were measured simultaneously, the CSF beta 2m level was significantly higher than the corresponding serum level in patients with CNS infection (6.98 +/- 2.5 vs 3.2 +/- 0.25 mg/l; P < 0.01). Sensitivity, specificity, and predictive values were estimated for different cut-off points. The best operational diagnostic cut-off value was 2.25 mg/l. Receiver operating characteristic curve analysis showed an appropriate trade-off between specificity and sensitivity and indicated that CSF beta 2m was accurate in distinguishing between neonates with and without CNS infection. Conclusion. CSF beta 2m may be a useful ancillary tool in neonates when CNS infection is suspected.

Tautomerism of bis(2-benzothiazolyl)methanes

Tautomerism of dibenzothiazolylmethane (1) and its C-methyl derivative (2) has been studied by 1H nuclear magnetic resonance, ultraviolet, and infrared spectroscopy using C,C-dimethyl (3) and N-methyl (4) derivatives as model compounds of the "CH" and "NH" forms, respectively. X-ray diffraction analysis of the "fixed" N-methyl derivative 4 shows that it corresponds to the Z-sE isomer 4b2. The CH tautomers are unstable in solution and they slowly isomerize into a mixture of NH tautomers that depends on the solvent and on the C-substituent (H or CH3).