title: Aqueous stability of astilbin: effects of pH, temperature, and solvent.
abstract: The influence of temperature, pH value, and solvent on the degradation behavior of astilbin was studied by HPLC. Results showed that the degradation of astilbin was pH and temperature dependent, and the isomerization of astilbin to its three stereoisomers was found. The degradation process followed the first-order kinetics model, and the degradation rate k values increased, whereas half-life (t1/2) values declined with the rise of pH and temperature. The stability of astilbin was related to its B-ring substitution. Engeletin with a 4'-hydroxy-substituted B-ring was more stable than astilbin with a 3',4'-dihydroxy-substituted B-ring. The stability of astilbin differed depending on the solvent and followed the order 50% ethanol > ethanol > methanol > 50% methanol > water. In cultural media, astilbin was less stable than in water, which may be related to the presence of metal ions. The stability results of astilbin were confirmed in the extraction of dihydroflavonols from Rhizoma Smilacis Glabrae and may have a guiding function in turtle jelly production.
authors.affiliation: Jiangxi Key Laboratory of Natural Product and Functional Food, College of Food Science and Engineering, Jiangxi Agricultural University , Nanchang 330045, China.
authors.forename: Qing-Feng
authors.initials: QF
authors.lastname: Zhang
authors.forename: Ying-Juan
authors.initials: YJ
authors.lastname: Fu
authors.forename: Zhan-Wang
authors.initials: ZW
authors.lastname: Huang
authors.forename: Xin-Cheng
authors.initials: XC
authors.lastname: Shangguang
authors.forename: Yu-Xian
authors.initials: YX
authors.lastname: Guo
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D004365:Drugs, Chinese Herbal / Q000737:chemistry*; D044948:Flavonols / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013696:Temperature
chemical_list: D004365:Drugs, Chinese Herbal; D044948:Flavonols; C099069:astilbin