Iridoid glycosides from noni (Morinda citrifolia L.) fruit pomace: A novel booster strategy for its extraction and will its α-glucosidase inhibitory be increased by acetylation?

Iridoid glycosides (IGs) are secondary metabolites found in plants such as the noni plant ( Morinda citrifolia L.), known for their diverse biological activities and potential health benefits. Herein, we screened fifteen natural deep eutectic solvents (NADES) and two conventional solvents (CS, 70% (V/V) methanol and 70% (V/V) ethanol) for extraction of IGs from noni fruit pomace. Our findings indicate that non-acidic NADES promote IG extraction. Glycerol/glycine combined with β-cyclodextrin was selected, and a molecular simulation was performed to elucidate the interaction between NADES components and IGs. Further, the structure-activity relationship and interaction mechanisms of IGs with α-glucosidase were investigated using multispectral and molecular docking tools. The results demonstrated that deacetylation of the B-ring's C-10 improved the inhibitory potential of IGs. Deacetylation produces hydrophobic contacts, which enhance the inhibitory effect of deacetylasperulosidic acid on α-glucosides. Additionally, hydrogen bonds and van der Waals forces drive the formation of non-covalent complexes between IGs and enzymes.