Studies on the interaction between HSA and new halogenated metformin derivatives: influence of lipophilic groups in the binding ability

Lipophilic Group-Modified Manganese(II)-Based Contrast Agents for Vascular and Hepatobiliary Magnetic Resonance Imaging

Effective vascular and hepatic enhancement and better safety are the key drivers for exploring gadolinium-free hepatobiliary contrast agents. Herein, a facile strategy proposes that the high lipophilicity may be favorable to enhancing sequentially vascular and hepatobiliary signal intensity based on the structure-activity relationship that both hepatic uptake and interaction with serum albumins partly depend on lipophilicity. Therefore, 11 newly synthesized derivatives of manganese o-phenylenediamine-N,N,N',N'-tetraacetic acid (MnLs) were evaluated as vascular and hepatobiliary agents. The maximum signal intensities of the heart, liver, and kidneys were strongly correlated with log P, a key indicator of lipophilicity. The most lipophilic agent, MnL6, showed favorable relaxivity when binding with serum albumin, good vascular enhancement, rapid excretion, and reliable hepatobiliary phases comparable to a classic hepatobiliary agent, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for in vivo liver tumor imaging. Inhibition experiments confirmed the hepatic targeting of MnL6 is mediated by organic anion-transporting polypeptides.

Molecular spectroscopic and docking analysis of the interaction of fluorescent thiadicarbocyanine dye with biomolecule bovine serum albumin

Binding studies of the water-soluble thiadicarbocyanine dye 3,3'-diethylthiadicarbocyanine acetate (DTC) with bovine serum albumin (BSA) were examined under physiological conditions using spectroscopic techniques like fluorescence, UV-Visible, circular dichroism (CD), FT-IR and molecular docking methods. Compiled experimental results envisage that DTC quench the fluorescence intensity of BSA. The increasing binding constants (K) were found to be in the order of 103 Mol-1 as a function of temperature, as calculated from the fluorescence quenching data. The quenching mechanism, thermodynamic parameters (ΔH0, ΔS0 and ΔG0) and the number of binding sites have been explored. CD values showed that the secondary structure of the BSA has been altered upon binding to DTC. Displacement experiments were carried out with different site probes to find out the binding site of DTC on BSA and it was found that binding interaction at site II of sub-domain IIIA. The interference of common metal ions on the interaction of DTC with BSA has also been studied. The experimental data exhibit that DTC interacts with BSA by hydrophobic forces. The experimental findings from BSA binding studies were validated by using in silico molecular docking technique. The results of the investigations were accurately supported by studies on molecular docking. The optimal shape of the molecular probe demonstrated the affinity as a free binding energy release of -7.37 Kcal/mol. The present research report endeavors to the approachable nature of water-soluble DTC dye and paves way for targeted biological interactions.Communicated by Ramaswamy H. Sarma.

New Synthetic Quinoline (Qui) Derivatives as Novel Antioxidants and Potential HSA's Antioxidant Activity Modulators-Spectroscopic Studies

The antioxidant activity of drugs, as well as the influence of drugs on the activity of endogenous antioxidant mechanisms in the human body is of great importance for the course of the disease and the treatment process. Due to the need to search for new therapeutic methods, the study of newly synthesized substances with potential therapeutic activity is necessary. This study aimed to designate some properties and characteristic parameters of new, synthetic quinoline three derivatives-1-methyl-3-allylthio-4-(4'-methylphenylamino)quinolinium bromide (Qui1), 1-methyl-3-allylthio-4-(3'-hydroxyphenylamino)quinolinium bromide (Qui2) as well as 1-methyl-3-allylthio-4-(4'-hydroxyphenylamino)quinolinium bromide (Qui3), including their antioxidant properties, as well as to analyse their activity as the potential modulators of Human Serum Albumin (HSA) antioxidant activity. In order to achieve the goal of the study, spectroscopic methods such as UV-Vis and circular dichroism (CD) spectroscopy have been used and based on the obtained data only slight and probably some surface interaction of quinoline derivatives (Qui1-Qui3) with HSA have been observed. The effect of Qui1-Qui3 on the HSA secondary structure was also insignificant. All analysed quinine derivatives have antioxidant activity against ABTS cation radical, in turn against DPPH radical, only Qui3 has noticeable antioxidant potential. The highest reduction potential by Qui3 as well as (Qui3 + HSA)_complex has been shown. Qui3 mixed with HSA has mostly the synergistic effect against DPPH, ABTS and FRAP, while Qui1 and Qui2 in the presence of HSA mostly have a synergistic and additive effect towards ABTS, respectively. Based on the obtained results it can be concluded that Qui2 and Qui3 can be considered potential modulators of HSA antioxidant activity.

Metformin Prevents or Delays the Development and Progression of Osteoarthritis: New Insight and Mechanism of Action

For over 60 years, metformin has been widely prescribed by physicians to treat type 2 diabetes. Along with more in-depth research on metformin and its molecular mechanism in recent decades, metformin has also been proposed as an effective drug to prevent or delay musculoskeletal disorders, including osteoarthritis (OA). The occurrence and development of OA are deemed to be associated with the impaired mitochondrial functions of articular chondrocytes. Metformin can activate the pathways and expressions of both AMPK and SIRT1 so as to protect the mitochondrial function of chondrocytes, thereby promoting osteoblast production. Moreover, the clinical significance of the metformin combination therapy in preventing OA has also been demonstrated. This review aimed to comprehensively summarize the current research progress on metformin as a proposed drug for OA prevention or treatment.

Spectroscopic and in silico insight into the interaction between dicofol and human serum albumin

Dicofol, a broad-spectrum acaricide, has garnered considerable attention because of the potential harm to the environment and various organisms. Herein, this study applied spectroscopic and in silico methods to understand the interaction between human serum albumin (HSA) and dicofol. Fluorescence experiments demonstrated that dicofol formed a stable complex and the binding process occurred in Suldow's site I of HSA. Its binding constant was 2.26 × 10⁵ M^-1 at 298 K. Van der Waals forces and hydrogen bond were primarily facilitated the interaction between dicofol and HSA (ΔH < 0, ΔS < 0) according to thermodynamic experiments. Additionally, 3D fluorescence and circular dichroism (CD) spectra revealed a few conformational changes in HSA due to dicofol. Molecular docking analysis indicated that dicofol interacted with Ser192, Gln196, Leu481, Arg218, Leu238, and Phe211 via van der Waals forces and formed a hydrogen bond with His242. Molecular dynamics (MD) simulation showed that Lys195 and Arg218 residues contributed greater energy for forming the HSA-dicofol complex. MD simulation analysis also showed that dicofol can affect the HSA structure with a reduction in α-helix. This research is desired to facilitate a new perspective on the toxicity mechanism of dicofol in the human body.

Porphyrin-Based Tumor-Targeting Theranostic Agent: Gd-TDAP

The aim of this work was to evaluate a tumor-targeting porphyrin-based gadolinium complex (Gd-TDAP) for use as an MR/optical imaging agent and potential therapeutic agent. Gd-TDAP had higher longitudinal relaxivity (11.8 mM-1 s-1) than a commercial MRI contrast agent (Omniscan; 3.7 mM-1 s-1) in HSA solution (0.67 mM) at 3 T. The tumor-targeting characteristics were confirmed by T1-weighted MR imaging and optical imaging using an orthotopic brain tumor mouse model, which showed 1.3-fold higher uptake in tumor compared to normal brain tissues. The cell fraction data using U87MG glioblastoma cells indicated the potential for gadolinium neutron capture therapy (Gd-NCT), which requires gadolinium to be inside the cell nucleus. In addition, porphyrin derivatives can be used for photodynamic therapy (PDT), and the results demonstrated that Gd-TDAP has great potential not only as a bimodal imaging agent but also for treatment.

Revealing the role of fluorine pharmacophore in chalcone scaffold for shifting the MAO-B selectivity: investigation of a detailed molecular dynamics and quantum chemical study

The development of highly selective monoamine oxidase-B (MAO-B) inhibitors has great therapeutic benefit in treatment of various neurodegenerative disorders. Recent study documented that shifting of fluorine atom from para to ortho position on the phenyl B ring of heteroaryl chalcones shown a remarkable shift in the selectivity and potency between MAO-A and MAO-B isoforms. Despite the large plethora of the design of new selective MAO-B inhibitors, the current paper illustrates the role and orientation of fluorine atom with remarkable MAO-B selectivity of three compounds (O23, O24 and O25), which differ from all other substituents encountered in the chalcone scaffolds is recently reported by our group. Conformational analyses of differential inhibitory effects of O23, O24 and O25 on MAO-A and MAO-B, differential analyses of complementary interactions at MAO-A/-B active sites and differential analysis of affinity binding and per-residue energy contributions are calculated by molecular dynamics study. Density functional theory based electronic structure calculations were employed with special emphasis to electrostatic potential and frontier molecular orbitals. Results of the current study can be used for lead modification and a new insight for the development of novel fluorinated chalcones for the treatment of various neurodegenerative disorders. Communicated by Ramaswamy H. Sarma.