UHPLC-MS -assisted characterization of bioactive alkaloids extracted from Nitraria sibirica leaves and enriched using response surface method and adsorption on macroporous resin

•Bioactive alkaloids were extracted from N. sibirica, a traditional Chinese medical plant.•The process was optimized by response surface modeling and Box-Behnken analysis.•The crude extracts were antioxidative, antimicrobial, and antitumorigenic.•Components were identified by UHPLC-Q-Orbitrap-MS.