Activity of arginine-phenylalanine and arginine-tryptophan-based surfactants against Staphylococcus aureus

Aims: This study aimed to evaluate the antibacterial effect of two new cationic surfactants based on phenylalanine-arginine (LPAM) and tryptophan-arginine (LTAM). Materials & methods: Antibacterial activity, mechanism of action and interactions with Staphylococcus aureus enzymes were measured through microbiological, flow cytometry and molecular docking assays, respectively. Results & conclusion: These compounds showed antibacterial activity in the range of 4.06-16.24 μg/ml against planktonic cells and no activity against mature biofilms, since they caused a loss of membrane integrity and increased DNA damage, as revealed by flow cytometry analysis. In silico assays revealed the existence of molecular bonds such as hydrogen bonds, mainly with DNA. Therefore, these compounds have promising pharmacological activity against MRSA strains.The authors would like to thank Central Analítica-UFC/CT-INFRA/MCTI- SISANO/Pró-Equipamentos CAPES for the support.Peer reviewe

Synthesis, characterization and photothermal analysis of nanostructured hydrides of Pd and PdCeO2

Abstract Hyperthermia was shown to be an important co-adjuvant therapy to conventional cancer treatments. Nanoparticles can be used in the hyperthermia therapy to improve the localized absorption of energy imposed by external sources, in order to kill tumor cells solely by the effect of heat and with minimum thermal damage to surrounding healthy cells. Nanoparticles can also serve as carriers of drugs that specifically act on the tumor when heated, including hydrogen that can be desorbed to locally promote an antioxidant effect and reduce the viability of cancer cells. In this context, palladium hydride nanoparticles emerge as promising materials for the hyperthermia therapy. In this study, palladium nanocubes (PdNC) and PdCeO2 nanoparticles were synthesized. Nanofluids produced with these nanomaterials were hydrogenated and then tested to examine their photothermal effects. Nanofluids made of PdHx nanoparticles presented significant temperature increases of more than 30 °C under 3 min of diode-laser irradiation. On the other hand, nanofluids with PdCeO2H nanoparticles presented temperature increases around 11 °C under the same experimental conditions. The behavior observed with the PdCeO2H nanofluids can be attributed to the effect of H+ in reducing Ce+4 to Ce+3

Analysis toxicity by different methods and anxiolytic effect of the aqueous extract Lippia sidoides Cham.

Abstract Lippia sidoides Cham. (Verbenaceae) is a species often mentioned in traditional medicine due to the medicinal properties attributed to its leaves, which include antibacterial, antifungal, acaricidal and antioxidant. Several of these actions have been scientifically proven, according to reports in the literature; however, little is known about toxicological aspects of this plant. This work included studies to determine the chemical composition and toxicity tests, using several methods aiming to evaluate the safety for use of the aqueous extract of L. sidoides leaves, in addition, the anxiolytic effect on adult zebrafish was investigated, thus contributing to the pharmacological knowledge and traditional medicine concerning the specie under study. The chemical profile was determined by liquid chromatography coupled to mass spectrometry-HPLC/MS with electrospray ionization. Toxicity was evaluated by zebrafish, Drosophila melanogaster, blood cells, and Artemia salina models. 12 compounds belonging to the flavonoid class were identified. In the toxicity assays, the observed results showed low toxicity of the aqueous extract in all tests performed. In the analysis with zebrafish, the highest doses of the extract were anxiolytic, neuromodulating the GABAa receptor. The obtained results support the safe use of the aqueous extract of L. sidoides leaves for the development of new drugs and for the use by populations in traditional medicine