Bioavailability Of Black Bean Sprouts Polyphenols In Simulated Digestion In Vitro And Their Inhibitory Effects On Digestive Enzymes

The black soybean[Glycine max(L.)Merr.]is a high-quality food resource and rich in nutrients and active substances.The polyphenols contents and activity of black soybean sprouts increase significantly during germination which has many physiological functions being as an important active substance.The optimum germination time of black soybean sprouts was determined by analyzing the polyphenols contents,composition and activity during germination.The contents and activity of black soybean sprouts polyphenols were determined by simulated digestion test in vitro to reveal their bioaccessibility.The inhibitory effects of black soybean sprouts polyphenols on ?-amylase,?-glucosidase and pancreatic lipase were assayed by enzymatic kinetics,and the inhibition types were revealed,which will provide a theoretical reference for the production of black soybean sprouts and the development and utilization of black soybean sprouts.The summary is as follows:(1)The contents of free phenols,ester-bonded phenols,glycoside-bonded phenols and total polyphenols in black soybean sprouts increased first and then decreased during germination and reached the highest value on the fourth day,which increased 126.06%,181.93%,300.00%and 157.14%compared with those before germination,respectively.The contents of genistein,daidzein,daidzein and total flavonoids in black soybean sprouts increased first and then decreased,and reached the maximum value on the fourth day of germination,which increased 46.26%,47.06%,527.24%and 302.67%compared with those before germination respectively,while the contents of daidzein,genistein and daidzein deseased during germination.Daidzein was not detected after 4 d of germination.The antioxidant activity of black soybean sprouts polyphenols was the strongest on the fourth day of germination and was consistent with the changes of polyphenols and flavonoids contents during germination.The FRAP antioxidant capacity,ABTS and DPPH radical scavenging ability increased 161.91%,168.24%and 162.35%on the fourth day than that before germination,respectively.(2)The contents and activities of soluble total polyphenols and total flavonoids,insoluble total polyphenols and total flavonoids of black soybean sprouts decreased after simulated digestion in vitro and the decreased order was stomach,small intestine and oral digestion.The bioaccessibility of soluble total polyphenols,soluble total flavonoids,insoluble total polyphenols and insoluble total flavonoids of black soybean sprouts was 95.53%,69.27%,98.10%and 96.00%after oral digestion in vitro while those were 70.57%,58.33%,85.55%and 82.40%after gastric digestion in vitro and which were 55.72%,54.17%,97.00%and 89.60%after small intestine digestion in vitro,respectively.(3)The black soybean sprouts polyphenols had high inhibitory activity on?-amylase,?-glucosidase and pancreatic lipase.The inhibitory activity of soluble polyphenols was weaker than insoluble polyphenols at a low concentration while they were same at a high concentration.The inhibition rates of black soybean sprouts soluble polyphenols and insoluble polyphenols on ?-amylase,?-glucosidase and pancreatic lipase were 89.5%,91%and 87%respectively,which were 90.00%,94.79%and 88.52%of acarbose and orlistatin at 10 mg/mL concentration.The inhibitory of soluble polyphenols from black soybean sprouts on ?-amylase,?-glucosidase and pancreatic lipase were competitive inhibition while insoluble polyphenols were non-competitive inhibition on ?-amylase and pancreatic lipase,and competitive inhibition on ?-glucosidase.The IC50 value of black soybean sprouts soluble polyphenols on ?-amylase,?-glucosidasewas and pancreatic lipase were 3.06 mg/mL,2.28 mg/mL and 3.56mg/mL while the insoluble polyphenols were 0.83 mg/mL,0.46 mg/mL and 2.41 mg/mL.