Spectroscopic and Molecular Modeling Studies of the Interaction Between 4′-O-(α-L-Oleandrosyl)daunorubicin and Human Serum Albumin and Its Analytical Application

Molecular interaction of some cardiovascular drugs with human serum albumin at physiological-like conditions: A new approach

In the present study, the interaction of human serum albumin (HSA) with some cardiovascular drugs (CARs) under physiological conditions was investigated via the fluorescence spectroscopic and Fourier transform infrared spectroscopy. The CAR included Captopril, Timolol, Propranolol, Atenolol, and Amiodarone. Cardiovascular drugs can effectively quench the endogenous fluorescence of HSA by static quenching mechanism. The fluorescence quenching of HSA is mainly caused by complex formation of HSA with CAR. The binding reaction of CAR with HSA can be concluded that hydrophobic and electrostatic interactions are the main binding forces in the CAR-HSA system. The results showed that CAR strongly quenched the intrinsic fluorescence of HSA through a static quenching procedure, and nonradiation energy transfer happened within molecules. Fourier transform infrared spectroscopy absorption studies showed that the secondary structure was changed according to the interaction of HSA and CAR. The binding reaction of CAR with HSA can be concluded that hydrophobic and electrostatic interactions are the main binding forces in the CAR-HSA system. The results obtained herein will be of biological significance in pharmacology and clinical medicines.

Studies on the binding of fulvic acid with transferrin by spectroscopic analysis

Transferrin has shown potential in the delivery of anticancer drugs into primarily proliferating cancer cells that over-express transferrin receptors. Fulvic acid has a wide range of biological and pharmacological activities which caused widespread concerns, the interaction of fulvic acid with human serum transferrin (Tf) has great significance for gaining a deeper insight about anticancer activities of fulvic acid. In this study, the mechanism of interaction between fulvic acid and Tf, has been investigated by using fluorescence quenching, thermodynamics, synchronous fluorescence and circular dichroism (CD) under physiological condition. Our results have shown that fulvic acid binds to Tf and form a new complex, and the calculated apparent association constants are 5.04×10(8) M(-1), 5.48×10(7) M(-1), 7.38×10(6) M(-1) from the fluorescence quenching at 288 K, 298 K, and 310 K. The thermodynamic parameters indicate that hydrogen bonding and weak van der Waals are involved in the interaction between fulvic acid and Tf. The binding of fulvic acid to Tf causes the α-helix structure content of the protein to reduce, and resulting that peptide chains of Tf become more stretched. Our results have indicated a mechanism of the interaction between fulvic acid and Tf, which may provide information for possible design of methods to deliver drug molecules via transferrin to target tissues and cells effectively.

Spectroscopic and Modelling Analysis on the Interaction of 3'-Azidodaunorubicin Semicarbazone with ctDNA

The synthesis and characterisation of a new anthracycline, 3′-azidodaunorubicin semicarbazone (ADNRS) is reported. The interaction between ADNRS and calf thymus DNA (ctDNA) was investigated by absorption and fluorescence spectroscopy in combination with melting temperature (Tm) curves and molecular modelling in physiological buffer (pH 7.4). Evidence indicates that ADNRS binds in the groove of ctDNA and the fluorescence quenching mechanism is a static quenching type. Calculated thermodynamic parameters show that hydrophobic interactions may play a predominant role in the binding. Furthermore, molecular modelling results corroborate the spectroscopic investigations.