Extraction Of Flavonoids From Winter-jujube Stone And Preliminary Exploration Of Its Biological Function

Jujube(Zyzyhpus Jujuba dates)is the fruit of Zizyphus Jujuba Mill plant, Zizyphus Mill, Rhamnacede. It is well-known that jujube date is abundant in nutriments, e.g. vitamin and minerals. Recently, it is also reported that jujube date contains different bioactive substances, such as cAMP, oleanolic acid, etc. Here we explored the optimal technical conditions for the extraction and purification of flavonoids from jujube stone, examined its antioxidant and antitumor activities in vitro, with expectation to provide some fundamental literature for multi-purpose utilization of jujubes and for finding bio-active substances from discarded natural plant. Therefore the study is important to enrich knowledge of food science and development of jujube industry.Our main results are as follows:1. The ethanol extraction and ultrasonic wave-assisted extraction are good methods for the extraction of flavonoids from jujube stone. The optimal parameters by ethanol extraction from jujube stone are: ethanol 60%, material/solvent ratio 1:20, extracting 2.0 hours at 80 ℃, for two times. The acquisition is 1321.75mg/100g.The optimal parameters by ultrasonic wave-assisted extraction from jujube stone are: ethanol 60%, material/solvent ratio 1:20, ultrasonic power 250W, extracting 1.0 hour at 80℃, for two times. The acquisition is 1344.81mg/100g.NaOH extraction and cellulase extraction are not as good as above.2. AB-8 macroporous resin is a good macroreticular resin for flavonoids from jujube stone with good adsorption and de-adsorption ability. The optimal parameters of purification for flavonoids from winter-jujube stone are: concentration of feed 0.1 ~ 0.5mg/mL, pH value 4.5, feeding rate 1mg/mL, eluted by 60% ethanol and alcohol volume 2.5BV. The purity of flavonoids from winter-jujube stone is 26.2% by the processing.3. Flavonoids from winter-jujube stone have antioxidant activity in vitro. They effectively scavenged free radicals in DPPH system and the superoxide anion radical system. The antioxidant activity increased with higher concentration of flavonoids from winter-jujube stone. In DPPH system, 42.7-81.1% DPPH radicals were eliminated when 5-25μg/mL of flavonoids were applied. The IC50 is 6.5μg/mL. With the concentration...