Deciphering the complexation process of a fluoroquinolone antibiotic, levofloxacin, with bovine serum albumin in the presence of additives

Binding studies of potential amyloid-β inhibiting chalcone derivative with bovine serum albumin

Chalcones (α-phenyl-β-benzoylethylene) and their natural-source derivatives have been investigated for their remarkable biological activities, like neuroprotective, anti-inflammatory, and anti-tumor properties. A triazole chalcone ligand (E)-3-(4-(dimethylamino)phenyl)-1-(4-((1-(2-(4-((E)-3-(4(dimethylamino)phenyl)acryloyl)phenoxy)ethyl)-1H-1,2,3-triazol-4-yl)methoxy)phenyl)prop-2-en-1-one (L1) was synthesized by Cu(I)- catalysed click reaction. The mechanistic properties of L1 for therapy were evaluated by analyzing the binding interactions between L1 and bovine serum albumin (BSA) through photophysical and computational studies. The structural elucidation of ligand L1 was carried out by NMR and mass spectrometry. The Aβ inhibitory activity of L1 was studied by thioflavin T assay and transmission electron microscopy. The biomolecular interaction of L1 with bovine serum albumin was examined through multi-spectroscopic techniques in combination with in silico studies. UV-Visible absorption, fluorescence spectroscopy, circular dichroism, Förster resonance energy transfer, and three-dimensional fluorescence studies confirmed the formation of a BSA-L1 complex. The potential binding sites, mechanism of interactions, and variations in the environment of tyrosine and tryptophan amino acid residues of BSA were assessed at different temperatures. The binding constant for the Static quenching mechanism of intrinsic fluorescence of BSA was of the order of 105 M-1. The esterase enzyme activity assay in the presence of L1 revealed an increase in the protein enzyme activity. Molecular docking studies suggested L1 was predominantly bound to BSA by hydrogen bonds and Van der Waals forces.

Cyclodextrins and Their Polymers Affect Human Serum Albumin's Interaction with Drugs Used in the Treatment of Pulmonary Infections

Respiratory infectious diseases have challenged medical communities and researchers. Ceftriaxone, meropenem and levofloxacin are widely used for bacterial infection treatment, although they possess severe side effects. To overcome this, we propose cyclodextrin (CD) and CD-based polymers as a drug delivery system for the drugs under consideration. CD polymers demonstrate higher binding affinity for levofloxacin (Ka ≈ 10⁵ M) compared to drug-CD complexes. CDs slightly alter the drugs' affinity for human serum albumin (HSA), whereas CD polymers increase the drugs' binding affinity up to 100 times. The most significant effect was observed for more the hydrophilic drugs ceftriaxone and meropenem. The drug's encapsulation in CD carriers leads to a decrease in the degree of change in the protein's secondary structure. The drug-CD carrier-HSA complexes demonstrate satisfying antibacterial activity in vitro, and even a high binding affinity does not decrease the drug's microbiological properties after 24 h. The proposed carriers are promising for a drug form with a prolonged drug release.

The Formation of β-Cyclodextrin Complexes with Levofloxacin and Ceftriaxone as an Approach to the Regulation of Drugs’ Pharmacokinetic

The study has been devoted to the complexation of hydroxypropyl-β-cyclodextrin (HPCD) with antibacterial drugs, namely, ceftriaxone (CT) and levofloxacin (LV), which are used to treat respiratory diseases, including bacterial infections of the respiratory tract. FTIR and NMR spectroscopic investigations have shown that the LV–HPCD complex is formed mainly due to the inclusion of the aromatic fragment of LV into the HPCD cavity; while the CT–HPCD complex is realized on the HPCD surface. Being a more hydrophobic molecule, LV forms ten times stronger complexes with HPCD than does CT: K_disLV-HPCD ~ 10^–3 M, while K_disCT-HPCD ~10^–2 M at pH 7.4. It has been shown that, for singly charged forms of the drugs, the complexes are two times more stable. Fluorescence spectroscopy has been employed to study the thermodynamic parameters for the interaction of dosage forms with human serum albumin. Negative values of ΔH and ΔS of the reaction have indicated both hydrogen bonding and van der Waals interactions during the complexation of both drugs with human serum albumin. It has been found that the protein is ~4 times more strongly bound to LV at 37°C as compared with CT. The data obtained will make it possible to improve the characteristics of the studied drugs and bring the methods of treating severe forms of respiratory diseases to a new level.

Effect of Methyl-β-Cyclodextrin on the Interaction of Fluoroquinolones with Human Serum Albumin

Abstract—

The influence of the structure of fluoroquinolones (on the example of ciprofloxacin and levofloxacin) and their complexation with methyl-β-cyclodextrin on the interaction of the drug with human serum albumin was studied. It was found that the binding of the drug molecule with albumin is significantly affected by the structure of fluoroquinolone, as well as the presence of methyl-β-cyclodextrin. It was discovered that of the two fluoroquinolones, the more hydrophobic ciprofloxacin molecule interacts more strongly with the protein, using circular dichroism and fluorescence spectroscopy methods. It has also been shown that binding of albumin to the drug causes quenching of protein fluorescence, and this effect is more pronounced for ciprofloxacin. The complexation of fluoroquinolones with methyl-β-cyclodextrin leads to a change in the interaction of fluoroquinolones with the protein: in the case of complexes, more pronounced interactions are observed for levofloxacin. The results obtained will help to bring the use of fluoroquinolones to a new level in clinical practice, by creating new highly effective drugs with improved properties.

Comparing the interaction of the antibiotic levofloxacin with zwitterionic and anionic membranes: Calorimetry, fluorescence, and spin label studies

The present work compares the interaction of the antibiotic levofloxacin (LVX) with zwitterionic and anionic liposomes composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG), respectively. By using differential scanning calorimetry (DSC), and with spin labels incorporated into liposomes at two different depths of the bilayers, we investigated the changes induced on the membrane by increasing concentrations of LVX. Further information was obtained using intrinsic LVX fluorescence. Under the conditions used here, all techniques evinced that LVX has little affinity for DPPC zwitterionic membrane. Opposite to that, LVX exhibits a considerable affinity for anionic bilayers, with membrane partition constants K_p = (3.3 ± 0.5) × 10² and (4.5 ± 0.3) × 10², for gel and fluid DPPG membranes, respectively. On binding to DPPG, LVX seems to give rise to the coexistence of LVX -rich and -poor domains on DPPG membranes, as detected by DSC. At the highest LVX concentration used (20 mol%), DSC trace shows an increase in the cooperativity of DPPG gel-fluid transition, also detected by spin labels as an increase in the bilayer packing. Moreover, LVX does not induce pore formation in either DPPG or POPG vesicles. Considering the possible relevance of LVX-membrane interaction for the biological and toxicological action of the antibiotic, the findings discussed here certainly contribute to a better understanding of its action, and the planning of new drugs.

Synthesis, Characterization, Photoluminescence, Molecular Docking and Bioactivity of Zinc (II) Compounds Based on Different Substituents

Six new zinc(II) complexes were prepared by the reaction of ZnBr₂ or ZnI₂ with 4′-(substituted-phenyl)-2,2′:6′,2′′-terpyridine compounds, bearing p-methylsulfonyl (L¹), p-methoxy (L²) and p-methyl (L³), which were characterized by elemental analysis, FT-IR, NMR and single crystal X-ray diffraction. The antiproliferative properties against Eca-109, A549 and Bel-7402 cell lines and the cytotoxicity test on RAW-264.7 of these compounds were monitored using a CCK-8 assay, and the studies indicate that the complexes show higher antiproliferative activities than cisplatin. The interactions of these complexes with CT-DNA and proteins (BSA) were studied by UV-Vis, circular dichroism (CD) and fluorescent spectroscopy, respectively. The results indicate that the interaction of these zinc(II) complexes with CT-DNA is achieved through intercalative binding, and their strong binding affinity to BSA is fulfilled through a static quenching mechanism. The simulation of the complexes with the CT-DNA fragment and BSA was studied by using molecular docking software. It further validates that the complexes interact with DNA through intercalative binding mode and that they have a strong interaction with BSA.

Profiling the interaction of Al(III)-GFLX complex, a potential pollution risk, with bovine serum albumin

Fluoroquinolone antibiotics (FQs), a new class of pollutants that seriously threaten human health through environmental and food residues, have aroused wide public concern. However, little attention has been paid to the potential toxicity of FQs' metal complex. Here, we firstly explore the proof-of-concept study of FQs' metal complex to bind bovine serum albumin (BSA) using systematical spectroscopic approaches. In detail, we have found that the complex of Al³⁺ with gatifloxacin (Al(III)-GFLX complex) can effectively bind to BSA via electrostatic interaction in PBS buffer (pH = 7.4, 1×), resulting in the formation of Al(III)-GFLX-BSA complex. The negative value of ΔG shows that the binding of Al(III)-GFLX complex to BSA is a spontaneous process. Circular dichroism spectra verify that Al(III)-GFLX complex effectively triggers the conformation changes of BSA's secondary structure. It has been proved that the interaction of small molecule with serum albumin has a significant effect on their in vivo biological effects such as absorption, distribution, metabolism, and excretion, and etc. Therefore, the results of this paper may offer a valuable theoretical basis for establishing safety standards of FQs' metal complex to ensure food and environmental health.

A comprehensive spectroscopic and computational investigation on the binding of the anti-asthmatic drug triamcinolone with serum albumin

Binding study of triamcinolone with BSA through in vitro and in silico approaches, helping in the development of drugs with better therapeutic efficacy.