Alkaline, Enzymatic Hydrolysis and Physicochemical Properties of 7-Theophyllineacetic Acid Derivatives
BOIKA TSVETKOVA1, JASMINA TENCHEVA1* AND PLAMEN PEIKOV2
1.Department of Chemistry, Faculty of Pharmacy, Medical University-Sofia, Bulgaria
2.Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Medical University-Sofia, Bulgaria
(Received: December 10, 2002; Accepted: June 23, 2003)
ABSTRACT
In the present study, a number of esters which derived from 7-theophyllineacetic acid were prepared. The stability of 7-theophyllinylacetyloxyglycols was evaluated in sodium hydroxide solution (pH 13.0) at 60℃. The degradation reaction was monitored by using a HPLC assay with ultraviolet detection. All of esters were hydrolyzed to yield the correspondence quantitative amount of the hydrolytic product. The rate constants of the hydrolytic decomposition of the described esters were estimated. The chemical mediated conversion displayed first-order kinetics, and half-lives of hydrolysis were determined, too. Also, the ability of the esters to release 7-theophyllineacetic acid through diluted human plasma at 37℃ was studied. Compounds were found to possess a high stability at these conditions. It was noticed that no spontaneous hydrolysis of ester derivatives was noticed within 24 hr as revealed by HPLC analysis. The aqueous solubility and lipophilicity (expressed as logP) of 7-theophyllineacetic acid and its esters were investigated by means of UV spectrophotometry. It was found that all of the esters were more lipophilic than its parent molecule. However, their solubility in aqueous media was decreased, compared by the parent drug.
Key words: 7-theophyllinylacetyloxyglycols, alkaline hydrolysis kinetics, enzymatic stability, partition coefficient, solubility, HPLC, UV spectrophotometry