Ascorbic Acid Binding Research Articles

Binding of colchicine and ascorbic acid (vitamin C) to bovine serum albumin: An in-vitro interaction study using multispectroscopic, molecular docking and molecular dynamics simulation study

Two or more drugs are prescribed commonly to patients depending on their physical health conditions. Concomitant drugs might lead to specific drug-drug interactions with serum albumin, the main transporter protein present in the blood. This study evaluated the effect of colchicine on the binding of ascorbic acid (vitamin C) commonly prescribed in viral infections to bovine serum albumin (BSA). The interaction was evaluated using fluorescence spectroscopy, absorption spectroscopy, molecular docking, and molecular dynamic simulation. A static quenching mechanism was observed for both BSA-colchicine and BSA-ascorbic interaction. The binding constant for the BSA-ascorbic acid system decreased from 1.23 × 105 to 0.26 × 102 in the presence of colchicine, whereas the binding constant of BSA-colchicine decreased from 1.39 × 105 to 4.81 × 102 in the presence of ascorbic acid. Thus, the binding of ascorbic acid and colchicine was significantly affected in the presence of each other. Co-administration of colchicine and ascorbic acid needs to be studied further as the co-administration may lead to serious adverse events in patients taking vitamin C supplements and under treatment with colchicine.

Binding of ascorbic acid and α-tocopherol to bovine serum albumin: a comparative study

Binding of ascorbic acid (water-soluble antioxidant) and α-tocopherol (lipid-soluble antioxidant) to bovine serum albumin (BSA) has been studied using isothermal titration calorimetry (ITC), in combination with fluorescence spectroscopy, UV-vis absorption spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. Thermodynamic investigations reveal that ascorbic acid/α-tocopherol binding to BSA is driven by favorable enthalpy and unfavorable entropy, and the major driving forces are hydrogen bonding and van der Waals forces. For ascorbic acid, the interaction is characterized by a high number of binding sites, which suggests that binding occurs by a surface adsorption mechanism that leads to coating of the protein surface. For α-tocopherol, one molecule of α-tocopherol combines with one molecule of BSA and no more α-tocopherol binding to BSA occurs at concentration ranges used in this study. Fluorescence experiments suggest that ascorbic acid has predominantly a "sphere of action" quenching mechanism, whereas, for α-tocopherol, the quenching mechanism is "static quenching" and due to the formation of a ground state complex. Additionally, as shown by the UV-vis absorption, synchronous fluorescence spectroscopy, and FT-IR, ascorbic acid and α-tocopherol may induce conformational and microenvironmental changes of BSA.

Natural Electrophoresis of Norepinephrine and Ascorbic Acid

The electric field produced by cell membranes, extending only a few nanometers, is 1000 times stronger than the electric fields required to produce dissociation of molecular complexes. Using the complex formed by norepinephrine (NE) and ascorbic acid (AA), we have demonstrated the quantitative binding of AA to NE, the use of capillary electrophoresis to measure quantitative binding of nonelectrolyte complexes, the determination of a dissociation constant (Kd) from electric field-dissociation constants (Ke), and a model for natural dissociation of the NE–AA complex due to the electric field generated by a cell membrane. NE–AA dissociation constants show little effect of NE concentration or pH changes. NE-related compounds also bind AA: epinephrine > norepinephrine > tyrosine > histamine > phenylalanine. Serotonin does not bind AA. Phosphorylated AA and glucose also bind NE at 0.05 and 0.08 of the AA binding, respectively. Natural electrophoresis of molecular complexes allows compounds to travel through the body in a protected state and still be available for physiological activity upon reaching a membrane.

Studies on the binding of ascorbic acid in animal tissues.

Summary1. The procedure of Sumerwell and Sealock, which yields evidence in favor of the exsitence of ascorbic acid in liver tissue in a bound form, was repeated. Results were in essential agreement with the work of these authors. 2. A study of the behavior of ascorbic acid in an aqueous liver homogenate under ultracentrifugation was made. At a centrifugal force of 100,000 × g a significant density gradient of ascorbic acid was formed. 3. Addition of urea in 3 N and 6 N concentrations had no influence upon the density gradients of ascorbic acid formed in aqueous liver extracts submitted to high speed centrifugation. 4. The results obtained are interpreted as evidence in favor of the assumption that ascorbic acid exists in tissues in a bound form.