Investigation of the Interaction Between Human Serum Albumin and Two Drugs as Binary and Ternary Systems.
OBJECTIVE
Human serum albumin (HSA) is the most frequent protein in blood plasma. Albumin transports various compounds, preserves osmotic pressure, and buffers pH. A unique feature of albumin is its ability to bind drugs and other bioactive molecules. However, it is important to consider binary and ternary systems of two pharmaceuticals to estimate the effect of the first drug on the second one and physicochemical properties.


METHODS
Different techniques including time-resolved, second-derivative and anisotropy fluorescence spectroscopy, resonance light scattering (RLS), critical induced aggregation concentration (CCIAC), particle size, zeta potential and stability analysis were employed in this assessment to elucidate the binding behavior of Amlodipine and Aspirin to HSA. Moreover, isothermal titration calorimetric techniques were performed and the QSAR properties were applied to analyze the hydration energy and log P. Multiple sequence alignments were also used to predict the structure and biological characteristics of the HSA binding site.


RESULTS
Time-resolved fluorescence spectroscopy showed interaction of both drugs to HSA based on a static quenching mechanism. Subsequently, second-derivative fluorescence spectroscopy presented different values of parameter H in binary and ternary systems, which were suggested that tryptophan was in a more polar environment in the ternary system than in a binary system. Moreover, the polydispersity index and results from mean number measurements revealed that the presence of the second drug caused a decrease in the stability of systems and increased the heterogeneity of complex. It is also, observed that the gradual addition of HSA has led to a marked increase in fluorescence anisotropy (r) of Amlodipine and Aspirin which can be suggested that the drugs were located in a restricted environment of the protein as confirmed by Red Edge Excitation Shift (REES) studies. The isothermal titration calorimetric technique demonstrated that the interaction of the drugs with HSA was an enthalpically-driven process.


CONCLUSIONS
The present experiment showed that the binding of Amlodipine and Aspirin to HSA induced a conformational change of HSA. It was also identified that the protein binding of the first drug could be affected by the second drug. Such results can be of great use for understanding the pharmacokinetic and pharmacodynamic mechanisms of drugs.
Department of Biology, Faculty of Sciences, Young Researchers and Elite Club, Islamic Azad University-Mashhad Branch, Mashhad, Iran.
Nooshin
N
Abdollahpour
Department of Drug Control, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran. Soheiliv881@mums.ac.ir.
Vahid
V
Soheili
Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
Mohammad Reza
MR
Saberi
Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad, Iran. chamani@ibb.ut.ac.ir.
Jamshidkhan
J
Chamani
D017311:Amlodipine / Q000737:chemistry / Q000378:metabolism*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000378:metabolism*; D000959:Antihypertensive Agents / Q000737:chemistry / Q000378:metabolism*; D001241:Aspirin / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D055598:Chemical Phenomena; D004347:Drug Interactions; D004355:Drug Stability; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D010316:Particle Size; D011487:Protein Conformation; D055550:Protein Stability / Q000187:drug effects; D058767:Protein Unfolding / Q000187:drug effects; D021281:Quantitative Structure-Activity Relationship; D000075462:Serum Albumin, Human / Q000737:chemistry / Q000378:metabolism*; D012995:Solubility; D013499:Surface Properties
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000959:Antihypertensive Agents; D017311:Amlodipine; D001241:Aspirin; D000075462:Serum Albumin, Human