Extraction, Purification And Antioxidant Activity Of Amygdalin In Loquat Seed

Loquat fruit is a special product fruit in subtropical region of China, and annual output is around40-60million tons. Loquat seed account for20%of loquat fruit.8-12million tons of loquat seed were disposed as garbage after processing every year, which caused the waste of resources. Amygdalin is the main medicinal ingredient of loquat seed which can dispel the phlegm, relieve the cough, resist the cancer assistantly and enhance the immunity. Therefore, extraction and purification of amygdalin from loquat seed were great significance.In this study, loquat seed was taken as a raw material. The basic ingredients and the content of amygdalin of differert varieties loquat seed were analysised. On this basis, optimization of the ultrasonic-assisted extraction and purification process of amygdalin from loquat seed were investigated. Besides, antioxidant activity of amygdalin was researched. Above studies were aimed to provide theoretical basis for the development and utilization of loquat seed. The main results were as follows:(1) Comparative analysis of the content of amygdalin in different varieties and different treatments of loquat seed was carried out in this study. The difference of the contents of amygdalin in different varieties was significant. The content of amygdalin in Jiefangzhong was highest, which is28.70±0.44mg/g. Secondly Qingzhong was24.66±1.17mg/g, and Guanyu was21.11±1.04mg/g. There was no significant difference in the content of amygdalin pre and post germination. Germination had a little effect on the content of amygdalin. The content of amygdalin in loquat seed decreased significantly after slow thawing at25℃and rapid thawing at100℃, which decreased to13.94%and72.27%. However, the content of amygdalin in loquat seed with steam killed enzyme keep stable in long-term storage. Loquat seed should be storage after killing enzyme by steam.(2) Ultrasonic-assisted extraction of amygdalin from loquat seed was optimized with response surface methodology on the basis of single-factor and two-level five-factor experiments. A second-order regression model was established with respect to extraction yield of amygdalin by using regression analysis. The determination coefficient of the model was0.9981. The result showed that the optimum extraction conditions of amygdalin from loquat seed were ethanol concentration75%, extraction temperature60℃, extraction time30min, liquid-to-solid ratio12:1, and ultrasonic power250W. The validation test indicated the extraction yield of amygdalin was39.07mg/g. The relative error was only0.66%between experimental value and the predicted value.(3) Five kinds of macroporous resins (D3520, AB-8, LSA-21, S-8, NKA-Ⅱ) to amygdalin were used to carry out static adsorption kinetics curves, adsorption isotherm and desorption characteristics, so as to find a better resin. It was indicated that the macroporous resin of LSA-21was the suitable resin for adsorption to amygdalin with the Balance velocity constant of absorption equilibrium (1.076). The maximal adsorption and desorption were139.71mg/g and133.07mg/g, respectively. The result shows that suitable temperature for adsorption was25℃, and60%ethanol solution was the optimum solution for desorption to amygdalin. The results of HPLC and Mass Spectrometry indicated that the purified material is amgdalin. The content of amgydalin is86.36±0.29%by using LSA-21macroporous resins. The crude amygdalin was purified by ethanol crystallization, and the getting ratio is80%.The content of amgydalin is93.33±0.32%.(4) Doing research on some phyisco-chemical properties and antioxidant activities of pure amygdalin. The DPPH radical-scavenging abilities, inhibited oxidation of lecithin activity, scavenging abilities on hydroxyl and the reducing power of amygdalin depended on their concentration. Although those capacities were lower than Vc, the purified amygdalin had a direct and effective antioxidant activity. Amygdalin is important to reducing the body’s free radical peroxidation.