In Silico, in Vitro and in vivo Ecotoxicology and Biodegradability Evaluations of Bioactive Schiff Base Ligand

Bioactive Schiff base ligand, 2-[(1E)-N-{2-[(2-{(Z)-[1-(2 hydroxyphenyl)ethylidene]amino} ethyl)amino]ethyl}ethanimidoyl]phenol was selected for in silico, in vitro and in vivo ecotoxicological and biodegradability studies. In vivo and in vitro ecotoxicological evaluations were estimated by the use of snails (Eobania vermiculata) and microorganisms’ bacteria and fungus respectively. In silico ecotoxicological and biodegradability predictions were carried out online computer software programs such as Pro Tox, Pred-skin, Endocrine Disruptor Knowledge Base (EDKB) and UM-BBD. The obtained results from in vivo bioassays showed moderate toxicity of the ligand at the high concentration (1000 µg/mL) with mortality percent value of 35%. For in vitro evaluations, results showed negative effect against bacteria and fungus. In silico predictions, results showed low toxicity with high LD50 of 4340 mg/kg, no toxic targets and low probability to bind with the majority of endocrine receptors with docking ranging between -7.4 and -8.9. In addition, the results from Human skin sensitization and Murine local lymph node assay indicate sensitizer effect of the ligand. For biodegradability prediction, the results indicate the ability of microorganism to degrade the ligand with no-toxic resultant products. We conclude the possibility to using the ligand without risks from environment and human health.                      

Review of QSAR Models and Software Tools for predicting Biokinetic Properties

In the assessment of industrial chemicals, cosmetic ingredients, and active substances in pesticides and biocides, metabolites and degradates are rarely tested for their toxicologcal effects in mammals. In the interests of animal welfare and cost-effectiveness, alternatives to animal testing are needed in the evaluation of these types of chemicals. In this report we review the current status of various types of in silico estimation methods for Absorption, Distribution, Metabolism and Excretion (ADME) properties, which are often important in discriminating between the toxicological profiles of parent compounds and their metabolites/degradation products. The review was performed in a broad sense, with emphasis on QSARs and rule-based approaches and their applicability to estimation of oral bioavailability, human intestinal absorption, blood-brain barrier penetration, plasma protein binding, metabolism and. This revealed a vast and rapidly growing literature and a range of software tools. While it is difficult to give firm conclusions on the applicability of such tools, it is clear that many have been developed with pharmaceutical applications in mind, and as such may not be applicable to other types of chemicals (this would require further research investigation). On the other hand, a range of predictive methodologies have been explored and found promising, so there is merit in pursuing their applicability in the assessment of other types of chemicals and products. Many of the software tools are not transparent in terms of their predictive algorithms or underlying datasets. However, the literature identifies a set of commonly used descriptors that have been found useful in ADME prediction, so further research and model development activities could be based on such studies.JRC.DG.I.6-Systems toxicolog

Revisiting the Tamoxifen Scaffold to Create Therapeutics to Treat Amphetamine Abuse

Amphetamine (AMPH) and its congeners are the second most widely abused drugs globally and their continued overuse comes with a high economic, health and social cost. Yet after decades of research, an effective treatment for AMPH abuse and addiction remains elusive. To tackle this unmet need, we have taken a step back to re-examine and further elucidate the mediators of AMPH reinforcement in hopes of finding novel targets for drug development. The reinforcing properties of AMPH are believed to stem from its reversal of the dopamine transporter (DAT), which greatly increases extracellular dopamine levels in the brain. Protein kinase C (PKC) is a major mediator of DAT localization and activity, and PKC activation facilitates AMPH-stimulated dopamine release. Inhibiting PKC attenuates the neurochemical and behavioral effects of AMPH. Therefore PKC inhibitors could be an appropriate pharmacological treatment for AMPH abuse and addiction. In pursuit of a blood-brain barrier permeant PKC inhibitor, we identified tamoxifen, a drug commonly used to prevent the recurrence of breast cancer, as a promising candidate. In fact, tamoxifen stands as the only validated CNS-permeant PKC inhibitor to date. Tamoxifen does act on other molecular targets, including the estrogen receptor (ER), and its promiscuity makes it an unattractive contender for AMPH abuse treatment. Nonetheless, tamoxifen has been the object of many structure-activity relationship studies and we have used the information from these investigations to make a new generation of selective CNS permeant PKC inhibitors based on the tamoxifen scaffold. I evaluated the actions of these tamoxifen analogues at PKC and ER, in hopes of finding compounds with increased selectivity for PKC inhibition and reduced ER affinity compared to tamoxifen. This led me to our lead compound, 6c, which asymmetrically modulates DAT functioning in in vitro rat models. Specifically, 6c more potently blocks dopamine efflux compared to uptake. I demonstrated that 6c does not elicit these effects on dopamine transport by altering DAT levels or binding near the dopamine substrate site. Significantly, as predicted, 6c crosses the blood-brain barrier and potently inhibits striatal PKC activity in vivo. I also illustrate that 6c has a direct effect on PKC and can disrupt PKC conformational changes without having effects on PKC translocation. Peripheral administration of the compound leads to significant decreases in AMPH-induced dopamine release, hyperlocomotion and reinforcement in vivo, predicting therapeutic effectiveness of 6c. Finally, I demonstrate that the in vivo effects of 6c are not due to its action on other closely related kinases that regulate DAT function. Together, the results from my thesis work highlight the potential of repurposing the tamoxifen scaffold to create new CNS-permeant PKC inhibitors and provide a foundation for developing therapeutics to treat AMPH addiction.PHDPharmacologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138545/1/ccarpen_1.pd

Screening virtual basado en topología molecular: una nueva metodología en el descubrimiento de agentes anticonvulsivos

La presente tesis se dividirá en dos partes. La primera de ellas, de carácter introductoria, versará sobre las motivaciones y los fundamentos del trabajo de tesis, describiendo la epilepsia y el estado actual de su terapéutica y proporcionando el marco teórico para comprender las bases y los alcances de los estudios QSAR, la Topología Molecular y las técnicas de Screening Virtual (SV). En la segunda se expondrán los resultados obtenidos mediante aplicación de estas metodologías en la búsqueda de nuevos fármacos anticonvulsivos.Facultad de Ciencias Exacta

Statistical learning approaches for predicting pharmacological properties of pharmaceutical agents

Ph.DDOCTOR OF PHILOSOPH