Abstract
Salvianolic acid B and rosmarinic acid are two main water-soluble active ingredients from Salvia miltiorrhiza with important pharmacological activities and clinical applications. The interactions between salvianolic acid B (or rosmarinic acid) and bovine serum albumin (BSA) in the presence and absence of gold nanoparticles (Au NPs) with three different sizes were investigated by using biophysical methods for the first time. Experimental results proved that two components quenched the fluorescence of BSA mainly through a static mechanism irrespective of the absence or presence of Au NPs. The presence of Au NPs decreased the binding constants of salvianolic acid B with BSA from 27.82% to 10.08%, while Au NPs increased the affinities of rosmarinic acid for BSA from 0.4% to 14.32%. The conformational change of BSA in the presence of Au NPs (caused by a noncompetitive binding between Au NPs and drugs at different albumin sites) induced changeable affinity and binding distance between drugs and BSA compared with no Au NPs. The competitive experiments revealed that the site I (subdomain IIA) of BSA was the primary binding site for salvianolic acid B and rosmarinic acid. Additionally, two compounds may induce conformational and micro-environmental changes of BSA. The results would provide valuable binding information between salvianolic acid B (or rosmarinic acid) and BSA, and also indicated that the Au NPs could alter the interaction mechanism and binding capability of drugs to BSA, which might be beneficial to understanding the pharmacokinetics and biological activities of the two drugs.
Highlights
In the past few years, there has been a rapid growth in the research of nanomaterials, which can be used in biotechnological, biomedical and industrial fields [1]
The synthesized Au NPs solutions exhibited a color of reddish brown, which was known to arise from the collective oscillation of the free conduction electrons induced by an interacting electromagnetic field
The binding mechanisms of Salvianolic acid B (SAB)/Rosmarinic acid (RA) interacting with bovine serum albumin (BSA) in the presence and absence of Au NPs with different diameters were investigated by spectroscopic methods
Summary
In the past few years, there has been a rapid growth in the research of nanomaterials, which can be used in biotechnological, biomedical and industrial fields [1]. A large number of nanoparticles have been synthesized, especially those made from noble metals such as gold. Gold nanoparticles (Au NPs) that possess novel optical, electronic and chemical properties have potential applications in chemistry and life sciences because of convenient surface bioconjugation with molecular probes and remarkable plasmon resonant optical properties [4]. In modern biological and medical studies Au NPs have been widely employed, including genomics, biosensor, immunoassay, laser phototherapy of cancer cells and tumors, immune response enhancement, the targeted delivery of drugs and optical bioimaging et al [5,6]. It is vital to understand the detailed reaction mechanism between Au NPs and biomolecules, especially the potential biological effect of Au NPs on the other life activities in vivo
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