Comprehensive Characterization of Curcumin, Rosolic Acid, and Ursolic Acid Formulations

A TA Instruments Q20 Differential Scanning Calorimeter (New Castle, DE, USA) was used for differential scanning calorimetry (DSC) analyses of pure curcumin, RosA, UrsA, BSA, drug formulations (Curcumin/BSA, RosA/BSA, and UrsA/BSA), and physical mixtures (PMs) of each drug with BSA. The instrument was calibrated using indium, and sample scanning was conducted under nitrogen gas at 20 mL/min. A DSC isotherm curve was generated for specimens in an aluminum pan with a lid at a temperature range of 40–300 °C (with a heat rate of 10 °C/min).
Next, in order to assess any crystalline properties of the formula, an X-ray diffractogram (XRD) was also measured for pure curcumin, RosA, UrsA, BSA, drug formulations (C/BSA, RosA/BSA, and UrsA/BSA), and physical mixtures (PMs) of drug and BSA. An Ultima IV diffractometer (Rigaku, Japan) was used with a voltage of 45 kV and a current of 30 mA for XRD patterns. The diffraction angle (2θ) of the sample was scanned between 0° and 90°. Furthermore, chemical component analysis results for each type of drug formula were obtained with an FT-IR 6300 spectrometer (JASCO, Tokyo, Japan). Potassium bromide pellets containing a single compound, physical mixtures, and formulations were used. Data were collected at a wavelength of 4000–400 cm⁻¹ at ambient temperature.