Enzymatic Preparation Of Prunin,Bioactivity Analysis And Microencapsulation Of Naringin And Converted Products

Naringin,a member of the flavanone group of flavonoids,has been reported to have many physiological activities.Prunin,the hydrolysate of naringin,has potential application prospect in the pharmaceutical,cosmetic,food industries,because of its various biological activities such as improvement of hyperglycemia,antineoplastic property,and well absorption by human body.Firstly,in order to avoid the disadvantages of chemical method,an alternative naringin enzymolysis method by naringinase was studied to obtain pure prunin.Next,compared between naringin and its enzymatic products,the antioxidant activities,antibacterial activities and suppressive activities of pancreatic?-amylase and lipase in vitro were detected and evaluated.Last,naringin and its hydrolysates prunin and naringenin were microencapsulated using sodium alginate and chitosan as carriers,and these microcapsules were used to investigate the drug release properties.The main results were listed as follows:Prunin could be accumulated during the process of naringin hydrolyzed by naringinase treated with pH 12 of Na₂HPO₄/NaOH buffer.The optimal condition for naringin bioconversion was determined as enzyme dosage 10 U/mL,substrate concentration 0.16%?w/v?,pH 4.0,temperature 50°C.Under this optimal condition,prunin could remain much higher concentration than naringenin and naringin was almost converted completely at 90 min.The final product,obtained through chemic extraction and solloca gel column chromatography,was prunin identified by ultraviolet spectrometry,IR spectrosopy and HPLC method,and the purity of prunin reached 99%.The antioxidant activities of naringin,prunin and naringenin in vitro were evaluated by DPPH,ABTS radical scavenging activites and Fe³⁺reducing activites.The IC₅₀ of naringin,prunin,naringenin and BHT against DPPH radical were 4.79±0.12 mg/mL,4.09±0.02mg/mL,18.21±0.25 mg/mL and 0.05±0.00 mg/mL,respectively,while the IC₅₀ of naringin,prunin,naringenin and BHT against ABTS radical were 0.57±0.03 mg/mL,1.03±0.06 mg/mL,0.23±0.02 mg/mL and 0.12±0.00 mg/mL.In addition,the reducing capacities of them were as follows in order:BHT>prunin>naringin>naringenin.The agar disk diffusion procedure was used to assess the antimicrobial activities of naringin,prunin and naringenin against three bacterial strains and three funguses.The antimicrobial experiments showed that naringin and prunin failed to inhibit the growth of all of the tested microorganisms,and naringenin only showed the inhibition on Escherichia coli.The assays of pancreatic?-amylase and lipase activities were used to evaluate the effects of hypoglycemic and hypolipidemic activities of naringin,prunin and naringenin.The study demonstrated that naringin,prunin,naringenin showed inhibitory activities against the pancreatic?-amylase and lipase.Their IC₅₀0 against pancreatic?-amylase were10146.46±2633.41 mg/mL,275.37±48.70 mg/mL,18.65±0.58 mg/mL,and the IC₅₀ against lipase were 146.90±24.87 mg/mL,1841.09±826.97 mg/mL,24.51±0.61 mg/mL.The microcapsules of naringin,prunin and naringenin were prepared by sharp hole-coagulation bath method using chitosan and sodium alginate as carriers.The optimal process parameters by orthogonal test was as follows:1.5%sodium alginate?the ratio of the core and sodium alginate was 1:2?,2%CaCl₂,0.2%chitosan,pH 5.5.Under these process parameters,the embedding rates of naringin,prunin and naringenin were 91.0%,90.2%and 91.4%.The study of the release of microcapsules showed that the microcapsules had delayed release both in the simulated gastric juice and intestinal juice,while the release rate was slower in the simulated gastric juice than that in the intestinal juice.