Fractionation of the Maca ( Lepidium meyenii Walp.) Leaf Extract Using Macroporous Resin Chromatography and Its Biological Properties

This study investigated the bioactivities of maca (Lepidium meyenii Walp.) leaf extract fractions obtained using deep eutectic solvent (DES)-based ultrasound-assisted extraction (UAE) followed by macroporous resin chromatography. Four fractions (Fr. 1 – Fr. 4) were obtained by elution with ethanol of varying concentrations (25%, 50%, 75%, and 100%, v/v ), and subsequently total phenolic content (TPC), total saponin content (TSC), and individual phenolic contents as well as their anti-inflammatory, antidiabetic, and antioxidant activity were determined. Pearson correlation analysis revealed that TSC and TPC were strongly associated with biological activities, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging activities, as well as α-glucosidase and nitric oxide (NO) inhibitory activities. Fr. 4, characterized by a high TSC (260.95 mg oleanolic acid equivalents (OAE)/g dry weight, DW), exhibited notable anti-inflammatory activity, inhibiting NO production by 36.30% at 60 μg/mL. Fr. 3, with TSC of 219.37 mg OAE/g DW and TPC of 53.45 mg gallic acid equivalents (GAE)/g DW, showed strong antidiabetic activity with an IC50 value of 0.24 mg/mL for α-glucosidase inhibition. Fr. 2, enriched in phenolic compounds and with high TPC of 104.78 mg GAE/g DW, demonstrated potent antioxidant activity, with IC 50 values of 0.52 mg/mL and 0.38 mg/mL in DPPH and ABTS assays, respectively. These results indicate that macroporous resin chromatography is effective in obtaining fractions enriched in phenolic compounds and saponins from maca leaf extracts prepared by DES-based UAE, highlighting their potential application as functional food ingredients.