Ultrasonication-assisted deep eutectic solvent extraction of flavonoids from pretreated fenugreek and their antidiabetic & hypo-lipidemic potential

The effects of germination pretreatments on fenugreek seeds were analyzed by employing an ultrasound-assisted deep eutectic solvent (UAE-DES) extraction process. The germinated and UAE-DES extracted fenugreek sample of day 3 (GFE₃) was found to be the most effective based on the results of flavonoid contents, antioxidant properties, and antibacterial potential. The results of HPLC-DAD analysis also suggested GFE₃ as an effective pretreatment with the highest extraction yields of kaempferol (5.33 ± 0.26 mg/gm d.w.), rutin (9.06 ± 0.44 mg/gm d.w.) and quercetin (25.69 ± 0.44 mg/gm d.w.) among all treatments. The results of simulated digestion showed that a major portion of flavonoid contents were lost during gastric digestion due to poor stability values and a maximum TFC release of 60.23% was recorded after intestinal digestion for GFE₃. Subsequently, GFE₃ exhibited good inhibition properties against α-amylase (86.53 ± 4.24%), α-glucosidase (95.67 ± 4.68%) and pancreatic lipase enzymes (82.73 ± 4.05%). Hence, GFE₃ can be used as a potential pretreatment for enhanced antioxidant activity and improved glycemic, lipid and digestive responses, which can be further used in food, nutraceutical and pharmaceutical industries.