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Journal of Spectroscopy
Volume 2013, Article ID 149615, 9 pages
http://dx.doi.org/10.1155/2013/149615
Research Article

Comparative Studies on the Interaction of Cochinchinenin A and Loureirin B with Bovine Serum Albumin

1Third Class Laboratory about Ethno-Medicine of State Administration of Traditional Chinese Medicine, College of Pharmacy, South-Central University for Nationalities, Wuhan 430074, China
2Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission & Ministry of Education, College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan 430074, China

Received 9 March 2013; Accepted 7 May 2013

Academic Editor: Renata Diniz

Copyright © 2013 Tianming Yang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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).