Green Biginelli Synthesis of Dihydropyrimidinone Derivatives Catalyzed by Phyllanthus acidus Fruit Extract: Structural Characterization and Preliminary Biological Evaluation

The development of environmentally sustainable synthetic approaches for biologically active heterocyclic compounds has become increasingly important in medicinal chemistry. In this study, two dihydropyrimidinone (DHPM) derivatives were synthesized through a green Biginelli multicomponent reaction using Phyllanthus acidus fruit extract as a natural acid catalyst. The synthesized compounds were characterized by UV-Vis, FT-IR, 1H NMR, and 13C NMR analyses. The effects of the volume of the catalyst on product yield were investigated, revealing optimal conditions of 3 and 7 mL, respectively, for DHPM-1 and DHPM-2. The biological potential of the synthesized compounds was evaluated through molecular docking, molecular dynamics simulation, and in vitro cytotoxicity assays against A549 cell lines. Molecular docking predicted moderate binding affinities of −5.8 and −5.5 kcal mol−1 for DHPM-1 and DHPM-2, respectively, compared with −7.5 kcal mol−1 for doxorubicin. Consistent with the computational results, DHPM-1 and DHPM-2 exhibited weak cytotoxic activity with IC50 values of 156.395 and 447.205 µg/mL, respectively. These findings indicated that although the present DHPM derivatives possess limited anti-lung cancer activity, the developed green synthetic strategy provides a route associated with lower environmental impact for preparing DHPM scaffolds that may serve as promising starting points for further structural optimization and biological investigation.