Staphylococcus aureus is known worldwide as the principal cause of human bacterial infections; as well as methicillin-resistant Staphylococcus aureus (MRSA), is a major cause of hospital-acquired infections that are becoming increasingly difficult to combat because of emerging resistance to all current antibiotic classes. This work aims to carry out a theoretical study of molecules derived from beta-lactam compounds with possible potential antibiotic activity on Staphylococcus aureus. Therefore, computational chemistry tools were used to describe the interactions between potentially active molecules and the transpeptidase and beta-lactamase enzyme. These molecules were docked with transpeptidase and beta-lactamase enzymes, and all of them showed a higher affinity for transpeptidase (−1.81 kcal mol−1) than the reference molecule (methicillin), but only two showed a lower affinity for beta-lactamase (−6.8 kcal mol−1). The two ligands that presented the best ranking docking results were subjected to molecular dynamics simulations to assess conformational stability through root mean square deviation (RMSD) and root mean square fluctuation (RMSF) analysis. According to simulation, the ligands that bind to the proteins do not cause significant conformational changes in the structures of the proteins. The absorption, distribution, metabolism, and excretion (ADME) properties of the molecules with the lowest affinity for beta-lactamase were estimated. The ADME properties predict that the molecules would have good bioavailability. methicillinresistant methicillin resistant MRSA, MRSA , (MRSA) hospitalacquired hospital acquired classes betalactam beta lactam Therefore betalactamase lactamase enzyme enzymes −1.81 181 1 81 (−1.8 mol−1 mol1 mol methicillin, (methicillin) −6.8 68 6 8 (−6. mol−1. . RMSD (RMSD RMSF (RMSF analysis simulation absorption distribution metabolism (ADME estimated bioavailability (MRSA −1.8 18 (−1. mol− (methicillin −6. (−6 −1. (−1 −6 (− −1 − (

RESUMEN Se han utilizado herramientas computacionales para proponer moléculas derivadas de cefalosporinas con potencial actividad antibacteriana, frente a cepas de Escherichia Coli, con mayor afinidad como inhibidores de enzimas de unión a penicilinas y que a su vez disminuyan o no tengan afinidad por betalactamasas de espectro extendido. Se diseñaron 20 moléculas con base en la estructura molecular de la cefalosporina, las estructuras fueron optimizadas utilizando la teoría del funcional de la densidad, se calcularon descriptores moleculares de reactividad, de forma paralela se sometieron a acoplamiento molecular con las enzimas antes mencionadas. Las moléculas presentaron valores de energía de unión negativos, doce moléculas mostraron una orientación e interacciones favorables en el sitio activo de la enzima de unión a penicilinas y trece moléculas presentaron menor afinidad que el ligando nativo (cefotaxima) por la betalactamasa. Tres moléculas pueden considerarse como potenciales inhibidores de enzimas de unión a penicilinas resistentes y betalactamasas.

SUMMARY Computational tools have been used to propose molecules derived from cephalosporins with potential antibacterial activity, against strains of Escherichia Coli, with higher affinity as inhibitors of penicillin-binding enzymes and which in turn decrease or do not have affinity for extended-spectrum beta-lactamases. 20 molecules were designed based on the molecular structure of the cephalosporin, the structures were optimized using the density functional theory, molecular descriptors of reactivity were calculated, and in parallel form they were subjected to molecular docking with the enzymes mentioned above. The molecules showed negative binding energy values, 12 molecules showed an orientation and favorable interactions in the active site of the penicillin binding enzyme and thirteen molecules had lower affinity than the native ligand (Cefotaxime) for betalactamase. Three molecules can be considered as potential inhibitors of binding enzymes to resistant penicillins and betalactamases.

Abstract: The method known as Quantitative Structure-Activity Relationship (QSAR) was applied to 33 Tipifarnib derived compounds. This was done with the aim of identifying the structural features responsible for the antichagasic activity against the Trypanosoma cruzi parasite, by simulating 33 molecules at the level of theory B3LYP/6-31+(d,p), followed by the evaluation of 1632 descriptors on the E-Dragon online platform. The model constructed by the descriptors RDF040v, E1p and R3e proved to be robust and predictive. The cross-validation yielded good values (R2=0.89; Q2=0.85), and R2 m=0.47. The proposed 18 molecules show a great pharmacological potential, particularly the 52, 53, 54 y 55 with an estimated EC50 of 0.33, 0.18, 0.18, and 0.34 nM respectively.

Resumen: En este trabajo aplicamos el procedimiento Relación Cuantitativa Estructura-Actividad (RCEA, o QSAR por sus siglas en inglés) a 33 compuestos derivados del Tipifarnib. Esto con el objetivo de identificar las características estructurales responsables de la actividad antichagásica contra el parasito del Tripanosomas cruzi, realizando una simulación con 33 análogos del Tipiofanib al nivel de teoría B3LYP/6-31+(d,p), seguido de la evaluación de 1632 descriptores en la plataforma E-Dragon online. Los descriptores RDF040v, E1p y R3e se utilizaron para construir los modelos, presentando buena calidad estadística. La validación presento valores de R2=0.89, Q2=0.86 y un R2 m=0.47. Las 18 moléculas que se proponen muestran un gran potencial farmacológico, particularmente, los compuestos 52, 53, 54 y 55 que presentan un alto potencial de actividad EC50 con valores estimados de 0.33, 0.18, 0.18, y 0.34 nM respectivamente.

The bacterial signaling mechanisms play a key role in the establishment and progression of periodontal disease. Due to these circumstances it is crucial to deepen in the understanding of these mechanisms to try to provide novel therapeutic strategies. The objective of present narrative literature review was to make a critical analyze of the available evidence on the influence of Porphyromonas gingivalis (PG) and the quorum sensing expression in periodontal disease. Using the Ovid (MEDLINE) ScienceDirect, Hinari database we made a search. The current knowledge of these mechanisms offers the possibility of developing new and deep studies (theoretical and experimental) on the QS expression in patients presenting with periodontal disease allowing a novel research field not currently available. From its discovery the QS is discerned as a valuable research space in which we must to insist in a permanent way. The above mentioned evidence allows concluding that by the regulation of the expression of determined genes in bacteria like PG, it is possible to carry out the inhibition in the formation of the biofilms with direct and indirect effects on the periodontal disease development.

Los mecanismos de señalización bacteriana desempeñan un papel fundamental en el establecimiento y progresión de la enfermedad periodontal. Dadas estas circunstancias es crucial profundizar en el entendimiento de estos mecanismos para intentar proveer estrategias terapéuticas novedosas. El presente artículo de revisión, de carácter narrativo, tiene como objetivo conducir un análisis crítico de la evidencia disponible sobre la influencia de Porphyromonas gingivalis (Pg) y expresión de quorum sensing (Qs) en enfermedad periodontal. Se realizó una búsqueda a través de bases de datos como Ovid (MEDLINE), ScienceDirect, Hinari. El conocimiento actual de estos mecanismos ofrece la posibilidad de desarrollar nuevos y profundos estudios (teóricos y experimentales) sobre la expresión del QS en pacientes con enfermedad periodontal y permitirá un novedoso campo de investigación con el que no se cuenta en la actualidad. Desde su descubrimiento, el QS se vislumbra como un espacio de investigación valioso en el cual se debe insistir de manera permanente. La anterior evidencia permite concluir que a través de la regulación de la expresión de determinados genes en bacterias como la PG, se puede efectuar la inhibición de la formación de las biopelículas que tiene efectos directos e indirectos sobre el desarrollo de la enfermedad periodontal.