Efficacy of a Combined Antiplatelet Therapy Is Not Affected by a Simultaneous Binding of Cangrelor and PSB 0777 to Albumin

Insight into the Effect of Submicellar Concentrations of Sodium Deoxycholate on the Structure, Stability, and Activity of Bovine and Human Serum Albumin: An Interesting Comparison between Single and Double Tryptophan Proteins

The progressive escalation in the applications of bile salts in diverse fields has triggered research on their interaction with various biological macromolecules, especially with proteins. A proper understanding of the interaction process of bile salts, particularly in the lower concentrations range, with the serum albumin seems important since the normal serum concentration of bile salts is approximately in the micromolar range. The current study deals with a comprehensive and comparative analysis of the interaction of submicellar concentrations of sodium deoxycholate (NaDC) with two homologous transport proteins: bovine serum albumin (BSA) and human serum albumin (HSA). HSA and BSA with one and two tryptophans, respectively, provide the opportunity for an interesting comparison of tryptophan fluorescence behavior on interaction with NaDC. The study suggests a sequential interaction of NaDC in three discrete stages with the two proteins. A detailed study using warfarin and ibuprofen as site markers provides information about the sites of interaction, which is further confirmed by inclusive molecular dynamics simulation analysis. Moreover, the comparison of the thermodynamics and stability of the NaDC-serum albumin complexes confirms the stronger interaction of NaDC with BSA as compared to that with HSA. The differential interaction between the bile salt and the two serum albumins is further established from the difference in the extent of decrease in the esterase-like activity assay of the proteins in the presence of NaDC. Therefore, the present study provides important insight into the effect of submicellar concentrations of NaDC on the structure, stability, and activity of the two homologous serum albumins and thus can contribute not only to the general understanding of the complex nature of serum albumin-bile salt interactions but also to the design of more effective pharmaceutical formulations in the field of drug delivery and biomedical research.

Picolylamine-functionalized benz[e]indole squaraine dyes: Synthetic approach, characterization and in vitro efficacy as potential anticancer phototherapeutic agents

Squaraine dyes are a family of compounds known for their relevant photophysical and photochemical properties potentially useful as photosensitizing agents. Since pyridines have been introduced into the skeleton of several families of compounds to enhance their pharmacological activity, and this approach had not yet been performed on squaraines, novel dyes derived from benz[e]indole functionalized with picolyl- and dipicolylamine and N-ethyl and -hexyl chains were designed and synthesized. After being fully characterized, their interaction with human albumin was in vitro and in silico evaluated. Dyes were further assessed for their phototoxicity activity, and the most interesting ones were studied regarding cell localization and induction of morphological cell changes, genotoxicity, apoptosis and cell cycle arrest. The molecules with N-ethyl chains showed the greatest in vitro light-dependent cytotoxic effects, particularly the zwitterionic squaraine dye and the one bearing a single pyridine unit, which also exhibited a more significant interaction with human albumin. Phenotypically, the cells incubated with these squaraines became smaller and rounded after irradiation, the effects varying with the tested concentration. Genotoxic effects were observed even without irradiation, being more evident for the N-ethyl picolylamine-derived dye. The fluorescence emitted by Rhodamine 123 largely coincided with that emitted by the dyes, suggesting that they are found preferentially in mitochondria. After irradiation, an increase in the subG1 population was verified by propidium iodide-staining analysis by flow cytometry, indicative of cell death by apoptosis.