SYNTHESIS AND IDENTIFICATION OF PILOCARPIC ACID DIESTERS, PRODRUGS OF PILOCARPINE

A series of new pilocarpic acid diesters were synthesized to obtain prodrugs for pilocarpine with varying physico-chemical properties. Thermospray liquid chromatography-mass spectrometry. (TSP-LC-MS), liquid chromatography with UV-detection (LC-UV) and NMR-spectroscopy were used for the identification of the synthetic products and for evaluation of their purity including typical impurities (pilocarpic acid monoester, pilocarpine). TSP-LC-MS-analysis was performed in the reversed-phase mode using acetonitrile (60%)-0.2 M ammonium acetate (40%) as mobile phase. In LC-UV-analysis chromatographic separation was carried out on a reversed-phase column and the mobile phase consisted of methanol (71%) and 0.02 M potassium dihydrogen phosphate, pH 4.5 (29%). Electron ionization-mass spectrometry (EI-MS) was used for elucidation of structures. Elemental compositions of the substances were verified with high resolution-mass spectrometry (HR-MS). The complete establishment of structures presented was based on H-1-, and COSY-NMR-spectroscopy joined to TSP-LC-MS-analysis.