Spectroscopic studies of simultaneous binding of cyclophosphamide and imatinib mesylate to human holo-transferrin

Experimental and in silico approaches for the buffalo whey protein-folic acid complexation elucidation. Molecular changes impacting on protein structure and functionality

Using a buffalo whey proteins concentrate (BWPC) as a nanocarrier of labile bioactive compounds as vitamins constitutes a very innovative approach with potential application in the food and nutraceutical industries. This work aims to deepen the knowledge of the phenomena occurring in the complexation process of vitamin B9 with BWPC, providing valuable information on the molecular and functional properties of complexes and intervening substances. For such purpose, analytical (SEC-FPLC, Fluorescence spectroscopy, FTIR, DLS, UV-vis spectroscopy) and in-silico methods (molecular docking) were performed to get complementary data. Five types of proteins were identified in the BWPC. Folic acid (FA) interacted with BWPC in buffer pH 7 through H-bonds and hydrophobic interactions, inducing conformational changes and modifying the secondary and tertiary protein structure. The resultant BWPC-FA complexes showed a size distribution in the nanoscale (100-150 nm) with no aggregation. Molecular docking showed that lactoferrin had the highest FA binding affinity. Complexation did not reduce the antioxidant activity of intervening substances. Indeed, the radical scavenging capacity of BWPC-FA was 20 % higher than single BWPC. The obtained results provide relevant data enabling the adding value of the main effluent of buffalo dairy industries.

Physicochemical characterization, in vitro and in vivo evaluation of chitosan/carrageenan encumbered with Imatinib mesylate-polysarcosine nanoparticles for sustained drug release and enhanced colorectal cancer targeted therapy

The objective of this investigation was to fabricate nanoparticles consisting of Imatinib mesylate-poly sarcosine-loaded chitosan/carrageenan in order to attain prolonged drug release and efficacious therapy for colorectal cancer. The study involved the synthesis of nanoparticles through the utilisation of ionic complexation and nanoprecipitation techniques. The subsequent nanoparticles were subjected to an assessment of their physicochemical characteristics, anti-cancer efficacy using HCT116 cell line, and acute toxicity. The present study examined two distinct nanoparticle formulations, namely IMT-PSar-NPs and CS-CRG-IMT-NPs, with respect to their particle size, zeta potential, and morphology. Both formulations demonstrated satisfactory characteristics, as they displayed consistent and prolonged drug release for a duration of 24 h, with the highest level of release occurring at a pH of 5.5. The efficacy and safety of IMT-PSar-NPs and CS-CRG-IMT-PSar-NPs nanoparticles were evaluated through various tests including in vitro cytotoxicity, cellular uptake, apoptosis, scratch test, cell cycle analysis, MMP & ROS estimate, acute toxicity, and stability tests. The results suggest that these nanoparticles were well fabricated and have promising potential for in vivo applications. The prepared polysaccharide nanoparticles have great potential for active targeting and could potentially reduce dose-dependent toxicity in the treatment of colon cancer.

Molecular interactions involved in the complexation process between buffalo whey proteins concentrate and folic acid

Using buffalo whey proteins as carrier agents of sensitive molecules raises an interesting approach allowing adding value and minimizing the pollution impact of this by-product. In this context, this work aims to explore the molecular interactions between buffalo whey proteins concentrate (BWPC) and folic acid (FA). For this purpose, fluorescence, UV and FTIR analysis were performed on aqueous or solid dispersions of a buffalo whey protein concentrate (5 μM) (BWPC), with variable concentrations (0-20 μM) of FA. Fluorescence and absorption data were fitted by Stern-Volmer, Beckett, Förster resonance energy transfer, and sphere-of-action models (R2 > 0.9). Derived results suggest that BWPC strongly bind to FA through non-covalent interactions and form ground-state complexes. Additionally, BWPC improves the photostability of FA against UV radiation, and chemical denaturation negatively affects the binding properties. Obtained results encourage further studies of BWPC as carrier agents, which could promote innovative applications for this under-utilized proteins source.

Turn-off fluorescence of nitrogen and sulfur carbon quantum dots as effective fluorescent probes for determination of imatinib. Application to biological fluids

Nitrogen and sulfur carbon quantum dots(N,S-CQDs) as effective fluorescent nanoprobes were synthesized through one-step-hydrothermal method using thiosemicarbazide (as nitrogen and sulfur source) and citric acid (as carbon source). The highly fluorescent N,S-CQDs were subjected to various characterization techniques. The fluorescence of the synthesized N,S-CQDs is characterized by maximum fluorescence emission at 415 nm after excitation at 345 nm and a high quantum yield of 0.58. The native N,S-CQDs fluorescence is quantitatively quenched upon addition of imatinib (IMA), so they are used for its spectrofluorimetric determination in its pharmaceutical formulations and biological fluids. Under optimal conditions, N,S-CQDs exhibited a "turn-off" fluorescence response to IMA over the range of 1.0 to 15.0 µg/mL with a limit of quantification of 0.42 µg/mL and a lower detection limit of 0.14 µg/mL. Stern-Volmer equation was used to study the mechanism of quenching and it was found to occur through static quenching mechanism. The method was extended to the in-vitro determination of the drug in spiked human urine and plasma samples and the percent recoveries were satisfactory.

X-ray Characterization of Conformational Changes of Human Apo- and Holo-Transferrin

Human serum transferrin (Tf) is a bilobed glycoprotein whose function is to transport iron through receptor-mediated endocytosis. The mechanism for iron release is pH-dependent and involves conformational changes in the protein, thus making it an attractive system for possible biomedical applications. In this contribution, two powerful X-ray techniques, namely Macromolecular X-ray Crystallography (MX) and Small Angle X-ray Scattering (SAXS), were used to study the conformational changes of iron-free (apo) and iron-loaded (holo) transferrin in crystal and solution states, respectively, at three different pH values of physiological relevance. A crystallographic model of glycosylated apo-Tf was obtained at 3.0 Å resolution, which did not resolve further despite many efforts to improve crystal quality. In the solution, apo-Tf remained mostly globular in all the pH conditions tested; however, the co-existence of closed, partially open, and open conformations was observed for holo-Tf, which showed a more elongated and flexible shape overall.