Purification of Alkaloids from Zanthoxylum bungeanum Using Macroporous Adsorption Resin and Evaluation of Their Biological Activities

Zanthoxylum bungeanum alkaloids have attracted considerable attention for their potential health benefits, yet systematic investigations into their extraction, purification, and comprehensive bioactivity remain scarce. In this study, an efficient extraction protocol was developed and scaled up, followed by purification using macroporous resin NKA-9 with 70% ethanol as the optimal eluent. Ultra-performance liquid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry (UPLC-IM-QTOF/MS) identified 11 major alkaloids in the 70% ethanol eluate fraction. The antioxidant capacity of the 70% ethanol eluate fraction was evaluated through DPPH, ABTS+·, and Fe3+ reducing power assays, revealing a clear dose-dependent effect, albeit weaker than ascorbic acid. Antibacterial screening against four pathogenic bacteria (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa) via the Oxford cup method, macrobroth dilution, and minimum bactericidal concentration (MBC) determination demonstrated strain-selective activity. The strongest effect was observed against E. coli [minimum inhibitory concentration (MIC) = 2 mg/mL, MBC = 8 mg/mL, MBC/MIC = 4, bactericidal], followed by moderate activity against B. subtilis (MIC = 4 mg/mL, MBC = 16 mg/mL), while only bacteriostatic effects were noted against S. aureus and P. aeruginosa within the tested range. These findings provide a robust foundation for further development of Zanthoxylum bungeanum alkaloids as natural functional ingredients or food-compatible bio preservatives.