α-Glucosidase Inhibiting Chromene Derivatives from Ageratum conyzoides L. Essential Oil Extracted via NADES-Assisted Hydrodistillation.

This work employed a green approach utilizing natural deep eutectic solvent (NADES)-assisted hydrodistillation for EO extraction from the aerial part of Ageratum conyzoides. Out of seven deep eutectic combinations used, glycerol-lactic acid (GLY:LA) (1 : 1) mixture significantly enhanced the yield from 0.78 mg/g (water as extraction media) to 1.00 mg/g. GC and GC-MS analysis revealed that EOs mainly contain (E)-β-caryophyllene (15.2-25.3 %), (E)-β-farnesene (2.7-8.2 %), and notably, precocene-I (8.2-18.0 %) and precocene-II (31.8-51.4 %), which varied significantly across different extraction media. Further column chromatography-based purification of EO led to the isolation of two known chromene derivatives precocene-I (1) and precocene-II (2). Precocene-I exhibited potent anti-diabetic activity (IC 0.26 mg/mL) compared to the standard drug acarbose. Among the EO samples, USK-N7, which had the highest percentage of precocene-I, showed the highest activity. The present study demonstrated the potential use of this weed plant as an anti-diabetic agent.