Purification And Structure Analysis Of Angiotensin Converting Enzyme Inhibitor In Mulberry Branch Bark

China is a traditional sericulture country, and it has abundant mulberry resource.As a traditional medicinal plant, Mulberry trees contain many kinds of activeingredients, for example flavonoids, alkaloids, polysaccharides and so on. Currently,the utilization of mulberry resource is still very low, except few part of mulberrybranches are used for culture medium to grow edible fungus. Every year a largenumber of mulberry branches are wasted and cause environmental pollution.Nowadays, People put more and more attention towards development and utilizationof mulberry branches. This study try to take mulberry branch bark as material, usingultrasonic assisted enzymatic method to extract ACE inhibitory compounds, and usingPlackett-Burman experimental design, steepest ascent experiment and responsesurface methodology to optimize its extract process. Then, ACE inhibitorycompounds are separated by ion exchange resin, sephadex, high performancechromatography(HPLC) and its structure is preliminarily studied.We extract ACE from fresh hog lung, then purify ACE by using saturationammonium sulfate fraction, Sephadex G-100gel filtration and Cellulose DE-52anionexchange chromatogram column. Pure ACE checked by SDS-PAGE test. Themolecular weight of ACE is approximately about180kDa and its specific activity is699.53U/mg.On the basis of PB experiment design and the steepest ascent experimental, Weusing response surface methodology to optimize extract process. Finally we determinethe optimal process conditions, as follows, mulberry branch bark concentration istaken as64.6g/L, the quantity of cellulase is to be3454.3U/g, ultrasonic power is87W, and extracting time is about68min. Under this conditions, the ACE inhibition rateof mulberry branch bark extraction can be reached to86%. The IC50value is2.19g/L.The scanning electron microscopy(SEM) results of the bark extract residue showedthat the ultrasonic assisted enzymatic is advantageous to release of active substances.Ultrasonic can make cellulase activity to be increased by1.67times. Ultravioletspectrum analysis found that cellulase change its ultraviolet absorption after ultrasonictreatment, it maybe happens due its relationship with enzyme activity increased.The bark extraction is purified by ion exchange resin, sephadex G-25and HPLC.Collecting active components, the ultraviolet spectrum analysis determines itsabsorption wavelength is225nm. Infrared spectrum analysis showed that the active compounds contain benzene ring. Liquid-mass spectrometry analysis found thatsubstance of preliminary purification is mixture. It contains nine compounds, themolecular weight of compounds within scope of107~888Da, main compounds weightis about216Da, followed by260Da.