Several authors have studied the release profile of drugs incorporated in different devices. However, to the best of our knowledge, although many studies have been done on the release of tetracycline, in these release devices, no study has investigated if the released compound is actually the tetracycline, or, instead, a degraded product. This approach is exploited here. In this work, we analyse the influence of two drying methods on the tetracycline delivery behaviour of synthesised glasses using the sol-gel process. We compare the drying methods results using both theoretical models and practical essays, and analyse the chemical characteristic of the released product in order to verify if it remains tetracycline. Samples were freeze-dried or dried in an oven at 37°C and characterised by several methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), differential thermogravimetric analysis (DTG), differential thermal analyses (DTA) and gas adsorption analysis (BET). The released concentration of tetracycline hydrochloride was studied as a function of time, and it was measured by ultraviolet spectrophotometry in the tetracycline wavelength. The drug delivery profiles were reasonably consistent with a diffusion model analysis. In addition, we observed higher release rates for the freeze-dried compared to those dried in an oven at 37°C. This higher release can be attributed to larger pore size for the freeze-dried sample systems with tetracycline, which promoted more water penetration, improving the drug diffusion. The analysis of the solution obtained in the release tests using high-performance liquid chromatography- mass spectrometry (HPLC-MS) confirmed that tetracycline was being released.
The antioxidant and chelating properties of essential oils of Syzygium aromaticum L. and Origanum vulgare L. and their principal eugenol and carvacrol constituents were evaluated by the thiobarbituric acid reactive substance (TBARS) assay and in the presence of iron(II) ions by cyclic voltammetry. In the TBARS assay, carvacrol and eugenol were more efficient than the butylated hydroxytoluene (BHT) standard. The anodic current of iron(II) decreased by 99.7% in the presence of S. aromaticum oil, 99.8% for eugenol, 89.3% for O. vulgare, and 99.4% for carvacrol. The UV spectra contained a band at 390 nm for the interaction between Fe(II) and ligands. Thermodynamically stable complexes are formed in the ratios of 1:3 Fe(II)/eugenol and 1:2 Fe(II)/ carvacrol. The essential oils and their principal constituents eugenol and carvacrol can be used in food preservation because they have a low cytotoxicity and act as antioxidants through chelation of metal ions.
Introduction: Pesticides have lethal properties, capable of controlling or eliminating a living organism; they block the organisms' vital metabolic processes. They cause serious problems for human health, as they are highly toxic. The most used pesticides that are considered toxic are known as organophosphothioates (OP/P=S) in their commercialized form and organophosphates (OP/P=O) in their active form. These compounds have been the subject of studies on their metabolism and toxicology. According to research, these pesticides' toxicity is increased when oxidative metabolic desulfurization reactions occur, with the P=S bond being transformed into a P=O bond. This toxicity is due to the ability of OP/P=O species to inhibit the human acetylcholinesterase enzyme (HssAChE). Methods: To study the oxidative biotransformation of OP/P=S pesticides and the inhibition of the HssAChE enzyme by OP/P=S and OP/P=O using the molecular docking technique and QM/MM calculations. Results: The theoretical results showed that parathion is the compound with the greatest capacity to transform its P=S bonds into P=O bonds, thus forming the active paraoxon metabolite in the oxidative biotransformation process. In the HssAChE inhibition by OP/P=S and OP/P=O, our results showed that of all the compounds investigated, those with the highest inhibitory activities are parathion, paraoxon, malathion, diazoxon, chlorpyrifos and omethoate. Conclusion: This study was essential due to the lack of information in the literature about the oxidative biotransformation process of OP/P=S pesticides and the ability of these compounds to inhibit HssAChE. With this study, it was possible to observe that, in the oxidative biotransformation, chlorpyrifos and parathion have greater capacities to transform into their active metabolites and in the inhibition of the HssAChE enzyme, it was possible to observe that not all OF/P=O are the ones with the highest abilities to inhibit the HssAChE enzyme.
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