A novel L-abrine salt with enhanced solubility and antioxidant activity

L -Abrine (N-Methyl- L -tryptophan, L-ABR) shows antioxidant and radical scavenging abilities in vitro but has low solubility. This research introduces a new L -abrine-oxalate (L-ABR-OXA) salt using grinding and solvent evaporation techniques. The structure was confirmed by single-crystal X-ray diffraction (SXRD), and its purity and stability were validated through PXRD, TGA, DSC, and FTIR analyses. A key innovation is the significant increase in solubility of L-ABR (4 times in water and 3 times in PBS) achieved through oxalate salt formation. This enhancement is backed by molecular electrostatic potential (MEP) and Hirshfeld surface analysis, which proved that hydrogen bonds are the primary factor driving the formation of salts. Antioxidant tests showed that L-ABR-OXA has superior radical scavenging and antioxidant activity at low concentrations compared to pure L-ABR, indicating its potential as a more effective bioactive formulation. This study offers a crystallography-based approach to improve the solubility and bioactivity of poorly soluble active pharmaceutical ingredients (API).