Study On The Extraction And Purification Method Of Amygdalin From Thinned Bayberry Kernel And Evaluation Of Its Functional Activity

Bayberry thinning is a fertility measure taken due to the bayberry fruit setting rate is too high, the thinned bayberry fruit is usually discarded. The chemical composition of thinned bayberry is similar to that of ripe fruit; its kernel also contains amygdalin. Currently, there is less study on the extraction, separation and purification of amygdalin from thinned bayberry kernel (TBK). In this study, the TBK amygdalin was extracted using ultrasonic-assisted extraction method, and its antioxidant activity in vitro and antitussive, were preliminary evaluated. The results were as follows:Selecting four different species bayberry of DongKui, BiQi, DingAo, WanDao, and collecting different thinning stages of kernels as raw material, the results showed that the kernel tended to be plump as bayberry fruit mature. The proportion of kernel accounted the stone was increasing, up to8.76%. The moisture content of was decreasing significantly (P<0.05), crude fat and crude protein contents were also significantly increased (P<0.05), and the total sugar content was not showing a regular change in four TBK species. The moisture, ash, fat, protein and total sugar content (fresh weight) were30.16%-92.87%、0.53%-3.23%、0.54%-41.67%、1.12%-20.67%and0.65%-3.38%.The amygdalin contents of each species in each stage of TBK were analyzed by HPLC method, and it was found that the amygdalin contents were significantly increased with the fruit mature (P<0.05). The content of amygdalin of the third thinning stage of DingAo species was the highest, reached28.25mg/g.Amygdalin from the third thinning stage of DingAo species was extracted using the ultrasonic-assisted extraction method. With the extraction yield as response value, the optimum extraction conditions were concluded as follows:ethanol concentration27%, solid-liquid ratio1:45(W/V), extraction time20min, extraction temperature44℃, and ultrasonic power250W. In this condition, the experimental value of amygdalin extraction yield was93.80%.This work developed a method for separation and purification of amygdalin from thinned bayberry kernels (TBKs) extracts, and the optimum separation parameters of amygdalin were:using D101type as the adsorption resins; initial amygdalin concentration of129to358mg/L;3BVs of water then11BVs of40%ethanol (aq.) for elution; loading and elution flow rates of2BV/h; Through one cycle of dynamic adsorption/desorption, the purity of amygdalin in the extract, determined by HPLC, increased17-fold from4.83%to82.00%, with77.94%average recovery.The antioxidant activity of amygdalin was studied by DPPH and ABTS antioxidant system, the results suggested that amygdalin had good scavenging activity of DPPH and ABTS free radical, and the concentration of amygdalin showed a good correlation with the scavenging rate. The DPPH free radical scavenging activities of crude and purified extracts were93.44and216.82mg/L in IC50value respectively, and the ABTS free radical scavenging activities was102.60and227.16mg/L, respectively. Furthermore, the crude extracts showed better antioxidant activity in vitro than purified extracts.Through the antitussive and expectorant experiment in mice, it was found that each dose of TBK crude extracts of45,90,180mg/kg could extend the incubation period of cough of ammonia cough mice, and reduce the number of cough times within2min, and the90mg/kg dose group could significantly extend the incubation period, compared with the control group (P<0.05). Each dose group of the TBK crude extracts and the amygdalin standard had no significant effect on the phenol red excretion, which suggested no significant expectorant activity.