A green four-step ethyl acetate-based approach for nuciferine extraction and purification from lotus leaves

A modified extraction and purification process for nuciferine from lotus leaves was developed in this study, offering a viable alternative to traditional techniques that necessitate extensive use of adsorption materials or raise significant environmental issues. This was achieved by employing an innovative two-phase solvent extraction (TPSE) system, which utilizes environmentally benign ethyl acetate (EtOAc) combined with a dilute Ca(OH)₂ solution. The TPSE system effectively destabilizes Pickering emulsions caused by herbal particles and tannin precipitate, facilitates gravity-driven phase separation, and results in high extraction efficiency (up to 97.4 %) within two 20 min cycles (15 min stirring, 5 min settling). The optimized extraction process, after reduced pressure concentration (RPC), is seamlessly integrated with pH-dependent liquid-liquid extraction (pHLLE), and cooling crystallization and recrystallization (CC&CRC), thereby eliminating the reliance on solid-phase adsorbents and petroleum ether as the extraction solvents in the pHLLE step. This integrated workflow maintains high purity (97.1 %) and overall recovery (52.3 %) of nuciferine. The simplified workflow, lower equipment requirements, and environmentally friendly solvent use contribute to a greener and potentially scalable process, aligning with principles of green chemistry and industrial eco-efficiency.