title: Ionization constants of ginkgolide B in aqueous solution.
abstract: The thermodynamic ionization constants (pK(a)(1), pK(a)(2), and pK(a)(3)) of ginkgolide B (9H-1,7a-(epoxymethano)-1H,6aH-cyclopenta[c]furo[2,3-b]furo-[3',2':3,4]cyclopenta[1,2-d]furan-5,9,12-(4H)-trione, 3-tert-butylhexahydro-4,7b,11-trihydroxy-8-methyl-) in aqueous solution have been settled by pH-metric and NMR studies. The three macroscopic pK(a) values as well as the water solubility and the water/n-octanol partition coefficient have been extracted from pH-metric data by means of a nonlinear regression methodology. NMR spectroscopy provided confirmation of the values of the macroscopic constants, information about the effective ionization pathways, and an estimation of the proportions of the various forms under physiologically relevant conditions.
authors: Département de Physicochimie et Biocinétique des Pharmaco-systèmes de l'Université de Rennes I, 2 avenue du Professeur Léon-Bernard, 35043 Rennes Cedex, France, Laboratoire de RMN Haute Résolution du Commissariat à l'Energie Atomique, Saclay, France, and IHB-IPSEN, 35 rue Spontini, 75116 Paris, France.
authors: O
authors: O
authors: Zekri
authors: P
authors: P
authors: Boudeville
authors: P
authors: P
authors: Genay
authors: B
authors: B
authors: Perly
authors: P
authors: P
authors: Braquet
authors: P
authors: P
authors: Jouenne
authors: J L
authors: JL
authors: Burgot