RESUMO

In this work, the leaves of K. tomentosa were macerated with hexane, chloroform, and methanol, respectively. The phytochemical profiles of hexane and chloroform extracts were unveiled using GC/MS, whereas the chemical composition of the methanol extract was analyzed using UPLC/MS/MS. The antibacterial activity of extracts was determined against gram-positive and gram-negative strains through the minimal inhibitory concentration assay, and in silico studies were implemented to analyze the interaction of phytoconstituents with bacterial peptides. The antioxidant property of extracts was assessed by evaluating their capacity to scavenge DPPH, ABTS, and H2O2 radicals. The toxicity of the extracts was recorded against Artemia salina nauplii and Caenorhabditis elegans nematodes. Results demonstrate that the hexane and chloroform extracts contain phytosterols, triterpenes, and fatty acids, whereas the methanol extract possesses glycosidic derivatives of quercetin and kaempferol together with sesquiterpene lactones. The antibacterial performance of extracts against the cultured strains was appraised as weak due to their MIC90 values (>500 µg/mL). As antioxidants, treatment with extracts executed high and moderate antioxidant activities within the range of 50-300 µg/mL. Extracts did not decrease the viability of A. salina, but they exerted a high toxic effect against C. elegans during exposure to treatment. Through in silico modeling, it was recorded that the flavonoids contained in the methanol extract can hamper the interaction of the NAM/NAG peptide, which is of great interest since it determines the formation of the peptide wall of gram-positive bacteria. This study reports for the first time the biological activities and phytochemical content of extracts from K. tomentosa and proposes a possible antibacterial mechanism of glycosidic derivatives of flavonoids against gram-positive bacteria.

RESUMO

The insecticidal property of ring C-seco limonoids has been discovered empirically and the target protein identified, but, to date, the molecular mechanism of action has not been described at the atomic scale. We elucidate on computational grounds whether nine C-seco limonoids present sufficiently high affinity to bind specifically with the putative target enzyme of the insects (ecdysone 20-monooxygenase). To this end, 3D models of ligands and the receptor target were generated and their interaction energies estimated by docking simulations. As a proof of concept, the tetrahydro-isoquinolinyl propenamide derivative QHC is the reference ligand bound to aldosterone synthase in the complex with PDB entry 4ZGX. It served as the 3D template for target modeling via homology. QHC was successfully docked back to its crystal pose in a one-digit nanomolar range. The reported experimental binding affinities span over the nanomolar to lower micromolar range. All nine limonoids were found with strong affinities in the range of -9 < ΔG < -13 kcal/mol. The molt hormone ecdysone showed a comparable ΔG energy of -12 kcal/mol, whereas -11 kcal/mol was the back docking result for the liganded crystal 4ZGX. In conclusion, the nine C-seco limonoids were strong binders on theoretical grounds in an activity range between a ten-fold lower to a ten-fold higher concentration level than insecticide ecdysone with its known target receptor. The comparable or even stronger binding hints at ecdysone 20-monooxygenase as their target biomolecule. Our assumption, however, is in need of future experimental confirmation before conclusions with certainty can be drawn about the true molecular mechanism of action for the C-seco limonoids under scrutiny.

Assuntos

RESUMO

Polyethylene (PE) is one of the most highly consumed petroleum-based polymers and its accumulation as waste causes environmental pollution. In this sense, the use of microorganisms and their enzymes represents the most ecofriendly and effective decontamination approach. In this work, molecular docking simulation for catalytic enzyme degradation of PE was carried out using individual enzymes: laccase (Lac), manganese peroxidase (MnP), lignin peroxidase (LiP) and unspecific peroxygenase (UnP). PE-binding energy, PE-binding affinity and dimensions of PE-binding sites in the enzyme cavity were calculated in each case. Four hypothetical PE biodegradation pathways were proposed using individual enzymes, and one pathway was proposed using a synergic enzyme combination. These results show that in nature, enzymes act in a synergic manner, using their specific features to undertake an extraordinarily effective sequential catalytic process for organopollutants degradation. In this process, Lac (oxidase) is crucial to provide hydrogen peroxide to the medium to ensure pollutant breakdown. UnP is a versatile enzyme that offers a promising practical application for the degradation of PE and other pollutants due to its cavity features. This is the first in silico report of PE enzymatic degradation, showing the mode of interaction of PE with enzymes as well as the degradation mechanism.

Assuntos

RESUMO

Se presentan 19 pacientes con testiculos tumorales estudiados con ecografía (transductor de 5 MHz) y su correspondiente confirmación quirúrgica. La ecografía demostró una alta certeza diagnóstica: 96,8% para determinar la localización de una lesión escrotal (intratesticular, extratesticular o mixta). Frente a las lesiones neoplásicas, el método demostró alta sensibilidad: 100%, baja especificidad: 64%, y 85% de certeza diagnóstica. Se analizan en detalle los signos ultrasonográficos asociados a patología tumoral, así como el origen de los 5 falsos-positivos que disminuyen la especificidad ecográfica

Assuntos

RESUMO

Se presentan 19 pacientes con testiculos tumorales estudiados con ecografía (transductor de 5 MHz) y su correspondiente confirmación quirúrgica. La ecografía demostró una alta certeza diagnóstica: 96,8% para determinar la localización de una lesión escrotal (intratesticular, extratesticular o mixta). Frente a las lesiones neoplásicas, el método demostró alta sensibilidad: 100%, baja especificidad: 64%, y 85% de certeza diagnóstica. Se analizan en detalle los signos ultrasonográficos asociados a patología tumoral, así como el origen de los 5 falsos-positivos que disminuyen la especificidad ecográfica (AU)

Assuntos

RESUMO

Se comunica el resultado del tratamiento de colecciones intraabdominales (absceso subfrénico, intrahepático, etc.), por punción percutánea, realizado a 7 pacientes. Se utilizó ecografía como guía, prefiriéndola a la tomografía computada. Estos casos realizados en 6 meses, han sido satisfactorios. No hubo mortalidad ni morbilidad. Se expone el tipo de agujas trocar y drenajes usados. También se comentan hallazgos bacteriológicos

Assuntos

RESUMO

Se comunica el resultado del tratamiento de colecciones intraabdominales (absceso subfrénico, intrahepático, etc.), por punción percutánea, realizado a 7 pacientes. Se utilizó ecografía como guía, prefiriéndola a la tomografía computada. Estos casos realizados en 6 meses, han sido satisfactorios. No hubo mortalidad ni morbilidad. Se expone el tipo de agujas trocar y drenajes usados. También se comentan hallazgos bacteriológicos (AU)

Assuntos