Fluoxetine competes with cortisol for binding to human serum albumin

Human serum albumin [HSA] is an important protein that carries variety of substances like some hormones and drugs in blood. Pharmacological studies of the interaction of many drugs and HSA are reported during several decades, specially recently years. Interaction of cortisol and fluoxetine hydrochloride [FLX] [as a common anti-stress drug] with HSA [as their carrier in blood] has been studied separately by using different spectroscopic techniques. Here, considering the increment of anti-stress drugs consumption, conformational change of HSA in presence of cortisol and FLX in 50 mM tris buffer, at pH = 7.5 and 37°C, is investigated via pH meter, UV absorption and fluorescence spectroscopy and circular dichroism methods. pH meter findings indicate that the acid denaturation of HSA in the presence of drug and cortisol occurs in the similar manner and this pattern is different relative to the denaturation of HSA in the absence of two reagents. The results of the other techniques consistent with the pH meter findings show that FLX effects on the physiochemical properties of HSA are as that of Cortisol. In-vivo study in Rats confirms in-vitro findings which means blood cortisol level increased in the presence of FLX. Experimental results indicate that FLX and cortisol alter the structural aspects of HSA in similar manner, so, this findings lead to the following reasonable "FLX is a competitive ligand for the binding of cortisol to HSA. Binding of FLX to HSA interferes to the interaction of cortisol-HSA"

effects of acetaminophen on human serum albumin [HSA]

Thermal conformational changes in human serum albumin [HSA] in present with a 10 mM phosphate buffer, at pH=7 have been investigated via circular dichroism [CD] and UV spectroscopic methods. The results indicate that temperature in a range of 25oC to 55oC could induce a reversible conformational change in the structure of HSA. The HSA phase transition corresponds to the physiological and pathological conditions of the body, especially fever. The conformational change observed in HSA is accompanied by a mild conversion of its secondary structures. Acetaminophen is a papular pain killer, and HSA is used as a drug carrier. Hence, acetaminophen could it interact with HSA. The study of HSA - acetaminophen interaction reveals the effects of acetaminophen on HSA structure, preventing it's phase transition. HSA - acetaminophen interaction leads to the stabilization of HAS. This interaction is accompanied with 8 kJ/mol of free energy change. The structural changes within HSA due to it's interaction with acetaminophen could be considered as a drug side effect and it may affect the protein functions