title: The structure-dependent self-association of five phenolic acids in aqueous solution.
abstract: Weak self-interaction plays an important role in interpreting the biomechanisms and modes of drug action. The structure-dependent self-association of five phenolic acids with various bioactivities, including danshensu (DSS), caffeic acid (CA), rosmarinic acid (RA), lithospermic acid (LA), and salvianolic acid B (SA), was investigated by (1)H NMR. These phenolic acids have similar condensed structures, with a CA moiety and varying numbers of DSS moieties. The strengths of the self-association constants are in the order DSS < CA < RA < LA < SA, which corresponds to the increasing molecular size of these phenolic acids and roughly corresponds to the increasing number of DSS moieties. The binding site for the self-aggregation of these phenolic acids has been identified to be on the CA moiety, rather than on the DSS moiety, as a result of CA's stronger aromatic π-π interactions, which cause larger chemical shift variations. The thermodynamic parameters for the self-association of these phenolic acids show that the self-association is spontaneous and enthalpically favorable at room temperature in all cases. It was inferred that π-π interactions and intermolecular hydrogen bonding stabilize the stacking structures of the phenolic acids. Knowledge of self-association processes will enable us to quantitatively assess the possible effects of self-aggregation on the interaction between drug and protein.
authors.affiliation: College of Life Sciences, Northwest University, Xi'an, 710069, China.
authors.forename: Chaoni
authors.initials: C
authors.lastname: Xiao
authors.forename: Man
authors.initials: M
authors.lastname: Wu
authors.forename: Yajun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Zhao
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Zheng
mesh_terms: D062385:Hydroxybenzoates / Q000737:chemistry*; D015394:Molecular Structure; D066244:Proton Magnetic Resonance Spectroscopy; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D062385:Hydroxybenzoates; D012996:Solutions; D014867:Water; C017616:phenolic acid
keywords: NMR; phenolic acid; self-association