Colorful Solvates and Miscellaneous Polymorphs of Celastrol: Characterization, Crystal Structure and Stability Study

As a crucial category of solid drug forms, the systematic study of solvates has emerged as a vital strategy for innovative drug development. This research focused on Celastrol, a pentacyclic triterpenoid compound known for its significant anti-inflammatory and antitumor properties, and successfully prepared and characterized 23 solvates. The study employed characterization techniques such as powder X-ray diffraction (PXRD), single-crystal X-ray diffraction (SCXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and hot stage microscopy (HSM), in conjunction with molecular conformation analysis, Hirshfeld surface (HS) analysis, and molecular electrostatic potential surface (MEPs) analysis. These methods were systematically utilized to explore the relationship between intermolecular forces and the formation of crystal forms, as well as the relationship between thermal stability and the spatial structure of Celastrol solvates. The research findings indicate that the spatial arrangement of Celastrol molecules and the properties of the solvents significantly influence the thermal stability of the solvates, with specific hydrogen-bonding networks and molecular stacking patterns playing a crucial role. This work not only elucidates the structure–property relationship of pentacyclic triterpenoid solvates but also provides an important theoretical foundation and technical reference for innovative formulation design using Celastrol extract from traditional Chinese medicine as a raw material.