Ionization Constants of Ginkgolide B in Aqueous Solution

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• 作者：Oussama Zekri ; Philippe Boudeville ; Philippe Genay ; Bruno Perly ; Pierre Braquet ; Philippe Jouenne ; and Jean-Louis Burgot
• 刊名：Analytical Chemistry
• 出版年：1996
• 出版时间：August 1, 1996
• 年：1996
• 卷：68
• 期：15
• 页码：2598 - 2604
• 全文大小：340K
• 年卷期：v.68,no.15(August 1, 1996)
• ISSN：1520-6882

文摘

The thermodynamic ionization constants(pK_a1,pK_a2, andpK_a3) 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 beensettled by pH-metric and NMR studies. The three macroscopic pK_a values as well as the watersolubility and thewater/n-octanol partition coefficient have beenextractedfrom pH-metric data by means of a nonlinear regressionmethodology. NMR spectroscopy provided confirmationof the values of the macroscopic constants, informationabout the effective ionization pathways, and an estimationof the proportions of the various forms under physiologically relevant conditions.