On improving the hygroscopic stability of palmatine chloride with crystalline palmatine sulfosalicyate pharmaceutical salt

Abstract

With the aim to improve the hygroscopic stability of palmatine chloride (PMTCl), an unreported single crystal of PMT—SSA (C21H20NO4·C7H5O6S·H2O) is prepared by the solvent evaporation method and characterized. A comprehensive analysis of the structure and Hirshfeld surface reveals that π—π stacking plays a crucial role in accumulating PMT—SSA. As expected, the hygroscopic stability of PMT—SSA is significantly improved compared with that of PMTCl. This may be due to the presence of π—π stacking in the structure of PMT—SSA which improves the hygroscopic stability. The present work inaugurates an avenue for improving the hygroscopic stability of active pharmaceutical ingredients and provides a novel crystalline product with a bright commercial prospect. Unfortunately, the maximum solubility of PMT—SSA is lower than that of PMTCl. How to improve its solubility will be explored in subsequent studies. However, it is surprising that PMT—SSA shows advantages with regard to antibacterial properties in comparison to PMTCl.