4 resultados para piperidines

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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Flavopiridol has been shown to potently inhibit CDK1 and 2 (cyclin-dependent kinases 1 and 2) and most recently it has been found that it also inhibits CDK9. The complex CDK9-cyclin T1 controls the elongation phase of transcription by RNA polymerase II. The present work describes a molecular model for the binary complex CDK9-flavopiridol. This structural model indicates that the inhibitor strongly binds to the ATP-binding pocket of CDK9 and the structural comparison of the complex CDK2-flavopiridol correlates the structural differences with differences in inhibition of these CDKs by flavopiridol. This structure opens the possibility of testing new inhibitor families, in addition to new substituents for the already known leading structures such as flavones and adenine derivatives. © 2002 Elsevier Science (USA). All rights reserved.

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Objective - To evaluate the effects of increasing doses of remifentanil hydrochloride administered via constant rate infusion (CRI) on the minimum alveolar concentration (MAC) of isoflurane in cats. Animals - 6 healthy adult cats. Procedures - For each cat, 2 experiments were performed (2-week interval). On each study day, anesthesia was induced and maintained with isoflurane; a catheter was placed in a cephalic vein for the administration of lactated Ringer's solution or remifentanil CRIs, and a catheter was placed in the jugular vein for collection of blood samples for blood gas analyses. On the first study day, individual basal MAC (MAC Basal) was determined for each cat. On the second study day, 3 remifentanil CRIs (0.25, 0.5, and 1.0 μg/kg/min) were administered (in ascending order); for each infusion, at least 30 minutes elapsed before determination of MAC (designated as MAC R0.25, MAC R0.5, and MAC R1.0, respectively). A 15-minute washout period was allowed between CRIs. A control MAC (MAC Control) was determined after the last remifentanil infusion. Results - Mean ± SD MAC Basal and MAC Control values at sea level did not differ significantly (1.66 ± 0.08% and 1.52 ± 0.21%, respectively). The MAC values determined for each remifentanil CRI did not differ significantly. However, MAC R0.25, MAC R0.5, and MAC R1.0, were significantly decreased, compared with MAC Basal, by 23.4 ± 79%, 29.8 ± 8.3%, and 26.0 ± 9.4%, respectively. Conclusions and Clinical Relevance - The 3 doses of remifentanil administered via CRI resulted in a similar degree of isoflurane MAC reduction in adult cats, indicating that a ceiling effect was achieved following administration of the lowest dose.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Multicomponent Reactions are defined as reactions between three or more reagents in a single reaction step in the same reaction vial, forming a product that includes the majority of atoms and structural characteristics of the reagents. Thus these reactions save time and energy. One of the ways to improve the yield and reaction time of a multicomponent reaction is to use different catalysts, an example of catalyst that shows great potential and has been studied in recent years is the molecular iodine is known to be a Lewis acid with high catalytic power. The functionalized piperidines, also known as tetrahydropyridines, are alkaloids that have pharmacological potential, this is due to the piperidine ring present in many natural product structures with muscarinic activity, nicotine, analgesic, antipsychotic, anti-proliferative, among others. In this paper we describe studies about on the application of molecular iodine (I2) in the multicomponent reaction between aniline derivatives, benzaldehyde and β-ketoester (methyl acetoacetate) for the synthesis of functionalized piperidines and the synthesis of a corresponding piperidone by acid hydrolysis. Data analysis allowed us to demonstrate the efficacy of molecular iodine in the synthesis of functionalized piperidines, obtaining results with yields 44-87% and short reaction time of 8 to 24 hours, and the efficacy of acid hydrolysis of enamine in the structure of the tetrahydropyridine derivative in a yield of 81%