A Potential Catechin Co-Crystal Strategy with Succinic Acid as Coformer to Improve Solubility

Abstract

Catechin, a flavonoid with potential health benefits, is indeed only slightly soluble in water, which can limit its bioavailability and effectiveness. One approach to enhance its solubility is co-crystallization or cocrystal, where catechin is combined with succinic acid as coformer to modify its crystalline structure. In this study, catechin-succinic acid cocrystals were prepared at a 1:1 mol ratio using Liquid Assisted Grinding Method (LAG) with ethanol p.a. as solvent. Physicochemical characterization was performed to confirm cocrystal formation. Crystallinity and structural properties were analyzed using FTIR (Fourier transform infrared spectrometry), XRD (X-ray diffraction spectrometry), and SEM (Scanning Electron Microscopy), while thermal behavior and melting point were evaluated using DSC (Differential Scanning Calorimetry). The aqueous solubility of cocrystal was determined to assess the effect of cocrystallization on the solubility enhancement of catechin. Thermal analysis observed change in melting points of cocrystals compared pure catechin and succinic acid that indicated eutectic compound were formed during the co-crystallization process. The result of FTIR analysis of cocrystals was shifted in the wavenumber spectrum compared to pure catechin and succinic acid indicated hydrogen bond between catechin and succinic acid was formed. SEM and XRD of crystal indicated a difference morphology and diffractogram compared to catechin and succinic acid that indicated new crystal was formed. The solubility test result obtained 124.58 mg/100 mL (catechin) and 151 mg/100 mL (cocrystal). Cocrystal of catechin and succinic acid have been successfully formed by LAG method and increased solubility.