Spectroscopic, thermal analyses, structural and antibacterial studies on the interaction of some metals with ofloxacin

Spectroscopic Analyses and Antimicrobial Activity of Novel Ciprofloxacin and 7-Hydroxy-4-methylcoumarin, the Plant-Based Natural Benzopyrone Derivative

Coumarin is highly distributed in nature, notably in higher plants. The biological features of coumarin include antibacterial, anticancer and antioxidant effects. It is well known that metal ions present in complexes accelerate the drug action and the efficacy of organic therapeutic agents. The main aim of the current study is the synthesis of different complexes of the interaction between ciprofloxacin hydrochloride (CIP) and coumarin derivative 7-hydroxy-4-methylcoumarin (HMC) with Zr(IV). The chelates of CIP with Zr(IV) were prepared and characterized by elemental analysis, melting point, conductance measurements, spectroscopic techniques involving IR, UV-Vis, ¹H NMR, and thermal behavior (TG-DTG) in the presence of HMC, dimethylformamide (DMF), pyridine (Py), and triethylamine (Et₃N). Results of molar conductivity tests showed that the new synthesized complexes are electrolytes with a 1:1 or 1:2 electrolyte ratio, with the chloride ions functioning as counter ions. According to IR spectra, CIP acts as a neutral bidentate ligand with Zr(IV) through one carboxylato oxygen and the carbonyl group, HMC as a monodentate through the carbonyl group, and DMF through the oxygen atom of the carbonyl group and the N atom of Py and Et₃N. The thermal behavior of the complexes was carefully investigated using TG and DTG techniques. TG findings signal that water molecules are found as hydrated and coordinated. The thermal decomposition mechanisms proposed for CIP, HMC, and Zr(IV) complexes are discussed and the activation energies (E_a), Gibbs free energies (∆G*), entropies (∆S*), and enthalpies (∆H*) of thermal decomposition reactions have been calculated using Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. The studied complexes were tested against some human pathogens and phytopathogens, including three Gram-positive bacteria (Bacillus subtilis, B. cereus, Brevibacterium otitidis) and three Gram-negative bacteria (Escherichiacoli, Pseudomonas aeruginosa and Klebsiella pneumoniae), and compared to the free CIP and HMC parent compounds.

Development of a Carrier-Free Dry Powder Ofloxacin Formulation With Enhanced Aerosolization Properties

Tuberculosis (TB) is a serious infectious disease that affects more than new 10 million patients each year. Many of these cases are resistant to first-line drugs so second-line ones, like fluoroquinolones, need to be incorporated into the therapeutic. Ofloxacin (OF) is a fluoroquinolone which demonstrates high antibiotic activity against the bacteria that causes TB (M. tuberculosis). In this work, ionic complexes, composed by hyaluronic acid (HA) and OF, with different neutralization degrees, were prepared and processed by spray drying (SD) to obtain powders for inhalatory administration. Combining a formulation with high neutralization degree, high SD atomization air flowrate and the use of a high-performance collection cyclone, very good process yields were obtained. Carrier-free formulations with a loading of 0.39-0.46 g_OF/g_powder showed excellent emitted, fine particle, and respirable fractions for capsule loadings of 25 and 100 mg. The ionic complexes demonstrated higher mucoadhesion than pure OF and HA. The best formulation did not affect CALU-3 cell viability up to a dose 6.5 times higher than the MIC₉₀ reported to treat multi-drug resistant TB.

Enhanced levofloxacin removal from water using zirconium (IV) loaded corn bracts

The presence of antibiotics in the environment has attracted considerable attention due to their toxicity. In this study, agricultural waste corn bracts (CBs) modified by zirconium cations were utilized to remove levofloxacin (LEV) from wastewater. Zr-modified CBs exhibited a strong adsorption capacity (Q_max = 73 mg/g), and their desorption rate could reach 89% by simply adjusting the pH to 11. FTIR and XPS analyses indicated that the mechanism of LEV adsorption included the complexation between the ketone/carboxyl groups of LEV and the Zr atoms and the π-π electron-donor-acceptor interaction. Zr-modified CBs are economic, effective and nontoxic adsorbents. This material not only removes antibiotics from wastewater but also enables recycling and reuse of agricultural waste.

Structural, optical, photoluminescence and antibacterial properties of copper-doped silver sulfide nanoparticles

The Ag2S and Cu doped Ag2S nanoparticles were prepared by simple chemical co-precipitation method and characterized by XRD, SEM, EDX, TEM, PL and UV-vis spectra. The photocatalytic activity of Ag2S and Cu doped Ag2S nanoparticles were investigated with Ofloxacin antibiotic, which is part of the fluoroquinolone family. The morphological study indicated that the products were spherical shape in with diameter size of 30nm. The photocatalytic results demonstrated that the Cu doping increased the photocatalytic efficiency of Ag2S nanoparticles. The outcome of antibacterial experiment under visible light irradiation indicate that the Cu doped Ag2S nanoparticles represent increased antibacterial performance compared with un-doped Ag2S nanoparticles.

Promising density functional theory methods for predicting the structures of uranyl complexes

By examining the overall accuracy of different theoretical methods in predicting the U–X bond distances (of a series uranyl complexes), we found that both the global-hybrid meta-GGA functional of BB1K and the range-seperated LC-BLYP functional are fairly good (even better than the popular B3LYP method).