Study On The Ultrasonic-assisted Extraction And Antioxidant Activity Of The Polyphenols From Helwingia Japonica

Helwingia japonica is a deciduous shrub in the Cornaceae family. In China, it ismainly distributed in the virgin forest which is1500m above sea level in Shanxi,Henan, and Yangze River and south of China. The species is a valuable plantresources with high ornamental value and medicinal value. In order to take furtheradvantage of this plant resource, a multi-purpose ultrasonic assisted extraction devicewas used to extract polyphenols from the Helwingia japonica in this paper. And thenthe extracts was separated and purified preliminarily in order to study the antioxidantactivity of Helwingia japonica polyphenols in vitro. All this work was to provide atheoretical basis for the development and utilization of helwingia japonica.First of all, the ultrasonic-assisted extraction process of Helwingia japonicapolyphenols was researched. The factors affecting the yield of polyphenols wereethanol concentration, ultrasonic time, ultrasonic power, solid-liquid ratio, andextraction temperature and extraction times. All these factors were studied andethanol concentration, ultrasonic time, solid-liquid ratio, extraction temperature werechosen to design esponse surface analysis tests to optimize the extraction process inaccordance with Box-Benhnken central composite experimental design principles.Optimum process parameters are ethanol concentration41%, ultrasonic time5min,solid-liquid ratio1:60(g:mL), extraction temperature67℃. In this case, theextraction of polyphenols was29.43mg/g.Secondly, the AB-8macroporous resin was selected to separate and purifyhelwingia japonica polyphenols as an adsorbent. Batch and continuous operation ofthe adsorption and desorption properties were studied to optimize the separation andpurification process. The batch condition was shock adsorption2h, macroporous resinextract ratio1:15(g: mL), extract polyphenol concentration2.5mg/mLand50%ethanol as eluent. The continuous operation conditions were as follows: feeding rate2mL/min, sample volume30mL, elution rate2mL/min, eluant volume60mL. And the content of helwingia japonica polyphenols in purified product was47.62%.Again, the antioxidant activity of helwingia japonica polyphenols was studied invitro. The restore capabilities of Fe3+ions as well as the clearance rate of ABTS+,DPPH, nitrite and hydroxyl radical were measured. And all these was compared withthe synthetic antioxidants Vc. The results indicated that within the concentrationrange of the experiment, the restore capabilities of helwingia japonica polyphenols forFe3+ions ability was stronger than the Vc; the clearance rate for ABTS+and DPPH on was better than Vc;compared with Vc, the clearance rate for nitrite and hydroxylradical were weak.