title: Reversed-phase liquid chromatographic analysis of hydrophobic interaction between proanthocyanidins and a C₈-alkyl compound in aqueous solution.
abstract: Structural and physicochemical properties of oligomeric flavan-3-ols (proanthocyanidins) in aqueous solution were investigated by spectrometric and reversed-phase (RP) HPLC analyses. Circular dichroism and fluorescence spectra of (-)-epicatechin (EC) oligomers linked through C-4 to C-8 interflavan bonds showed that EC oligomers larger than dimers formed a stable secondary structure in water. These EC oligomers are water-soluble hydrophilic compounds, whereas the oligomers were strongly retained by a C8-alkyl stationary phase under conventional RP-HPLC conditions. In a further C8-HPLC study, the hydrophobic interaction between EC oligomers and 1-octanesulfonic acid sodium salt (OSA Na) added to the mobile phase was quantitatively evaluated based on the relationship between the logarithm of the retention factor of the solute and the OSA Na concentration in the mobile phase. The strength values of the hydrophobic interaction of EC oligomers larger than dimers were the highest of 22 tested polyphenolic standards.
authors.affiliation: a Division of Pharmaceutical and Biomedical Analysis , School of Pharmacy, Tokyo University of Pharmacy and Life Sciences , Hachioji , Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Yanagida
authors.affiliation: a Division of Pharmaceutical and Biomedical Analysis , School of Pharmacy, Tokyo University of Pharmacy and Life Sciences , Hachioji , Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Takeshige
authors.affiliation: a Division of Pharmaceutical and Biomedical Analysis , School of Pharmacy, Tokyo University of Pharmacy and Life Sciences , Hachioji , Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shibusawa
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D002942:Circular Dichroism; D006838:Hydrocarbons / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D044945:Proanthocyanidins / Q000737:chemistry*; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014867:Water
chemical_list: D006838:Hydrocarbons; D044945:Proanthocyanidins; D012996:Solutions; D014867:Water
keywords: 1-octanesulfonic acid; circular dichroism; hydrophobic interaction; proanthocyanidins; reversed-phase liquid chromatography