%0 Journal Article
%T Comparative Studies on the Interaction of Cochinchinenin A and Loureirin B with Bovine Serum Albumin
%A Tianming Yang
%A Hao Zhang
%A Haiyan Fu
%A Yuanbin She
%A Can Huang
%A Yan Hu
%A Liping Wang
%J Journal of Spectroscopy
%D 2013
%R 10.1155/2013/149615
%X This paper describes the simple, sensitive, and effective spectrophotometric methods based on ultraviolet, fluorescence and circular dichroism for revealing the interactional mechanism of Cochinchinenin A (CA) and Loureirin B (LB) with bovine serum albumin (BSA). Under simulated physiological conditions, it was demonstrated that the fluorescence quenching mechanisms between CA (or LB) and BSA as a static quenching mode, or a combined quenching (dynamic and static quenching) mode were related to concentration level of CA (or LB). The binding distance ( , ) and the quenching efficiency ( ), especially for the binding constants value of ligands to BSA, were affected by the methoxyl group at position 4 at different temperatures. The corresponding thermodynamic parameters were also obtained and indicated that electrostatic forces play a major role in the formation of the LB-BSA complex, but probably a combined force for CA-BSA complex. Furthermore, synchronous fluorescence spectroscopy and circular dichroism spectra demonstrated that the secondary structures of BSA were changed to varying degrees by the binding of CA (or LB). 1. Introduction Cochinchinenin A (CA) and Loureirin B (LB) are important bioactive ingredients of Dragon¡¯s blood, which is a deep red resin and has been used as a famous traditional medicine since ancient times by many cultures. The deep red resin of Dracaena cochinchinensis (Lour.) S. C. Chen (Agavaceae), believed to be the original source of Chinese dragon¡¯s blood, has been widely used in traditional Chinese medicine for promoting blood circulation, treating trauma, relieving pain, visceral hemorrhages, antimicrobial, mainly for the treatment of coronary heart disease, cerebral infarction, and other thrombotic diseases [1¨C4]. CA (4¡ä-hydroxy-2,6-dimethoxydihydrochalcone) and LB (4¡ä-hydroxy-2,4,6-trimethoxydihydrochalcone) (Figure 1) as the synergistic bioactive ingredients of Dragon¡¯s Blood extracts were shown to have certain antithrombotic effects, antiplatelet aggregation effects, anti-inflammatory, and analgesic effects [5¨C8]. In spite of these broad pharmacological actions of CA and LB mentioned earlier, their effects on proteins and the mechanisms of actions are poorly understood. Additionally, the interaction between drugs and proteins could significantly affect the transportation and distribution of CA and LB and also affect their therapeutic activity and toxicity [9, 10]. As seen in Figure 1, the only difference in structure is that there is one more methoxyl group in 4-substitution of LB. Consequently, studies on the
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