title: Kinetics and mechanism of degradation of lithospermic acid B in aqueous solution.
abstract: The degradation of lithospermic acid B (LAB) was investigated as a function of buffer concentration, pH and temperature. Stability tests were performed using a stability-indicating high-performance liquid chromatography (HPLC) with UV-vis detection. The degradation followed pseudo-first-order kinetics under all experimental conditions. The maximum stability of LAB was observed at pH 2.0. The logk(pH)-pH profile described by specific acid-base catalysis and water molecules agreed with the experimental results. The overall degradation rate constant as a function of the temperature under the given conditions obeyed the Arrhenius equation. The chemical fate of LAB in mild acidic solution was investigated, and nine degradation products were detected and tentatively identified by LC-MS analysis. The primary degradation pathway involving the cleavage of ester bond and ring-opened of benzofuran in the LAB are proposed.
authors.affiliation: Department of Bioscience & Biotechnology, Dalian University of Technology, Linggong Road 2, Dalian 116024, PR China.
authors.forename: Yong-Xue
authors.initials: YX
authors.lastname: Guo
authors.forename: Zhi-Long
authors.initials: ZL
authors.lastname: Xiu
authors.forename: Dai-Jia
authors.initials: DJ
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Long-Xing
authors.initials: LX
authors.lastname: Wang
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Xiao
mesh_terms: D001572:Benzofurans / Q000032:analysis / Q000737:chemistry*; D002021:Buffers; D002853:Chromatography, Liquid; D053630:Depsides / Q000032:analysis / Q000737:chemistry*; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013058:Mass Spectrometry; D008958:Models, Molecular; D012996:Solutions / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D001572:Benzofurans; D002021:Buffers; D053630:Depsides; D012996:Solutions; D014867:Water; C076944:salvianolic acid B