Enzymatic Acylation Of Bamboo Leaves Flavonoids And Antioxidant Properties

Flavonoids from bamboo leaves are a new kind of flavonoid with Chinese characteristics local resources in recent years. Studies have shown that bamboo Leaves flavonoids have excellent anti-free radical, anti-oxidation, anti-mutagenic and protect cardiovascular and other health effects. The main contents and results are as follows:By high performance liquid chromatography(HPLC), isolation and identification of commercially available Flavonoids from Bamboo leaves have been done: selecting Synthesis C18 column(250mm×4.6mm, 5um), which successfully separated four flavonoid glycosides.Identified as four kinds of C-glycosides flavonoids:Vitexin、Orientin、Isovitexin、Isoorientin. With external standard,the contents of four flavonoid glycosides were: Isoorientin was 58.51%, Orientin was 16.79%,Vitexin was 4.34%, Isovitexin was 18.36%;The results showed that: Isoorientin > Isovitexin> Orientin > Vitexin.Immobilised Candida Antarctica lipase B(Novozmy 435) was used to acylate flavonoids from bamboo leaves, with eighteen carbon fattyacids of different saturation(C18:0、C18:1、C18:2) as acyl donors. Ultimately scored two acylated derivatives of isovitexin and Isoorientin after separation and purification. The purified products were analyzed by IR, ESI-MS, 1H-NMR and 13C-NMR,and the acylation site is located at 6 "-bit of isovitexin and Isoorientin. At the same time, we measured and compared the octanol / water partition coefficient of the two acylated products, the results showed that the acylated product lipophilic improved significantly.In this part, the study of the vitro antioxidant activity of acylated derivatives of isoorientin-6″- oleate and isovitexin-6″- oleate was done.The antioxidant activity of acylated products were evaluated through different antioxidant tests, including the reducing ability,induction time values in sunflower oil, reducing DPPH radical scavenging activity and hydroxyl radical scavenging activity. The results showed that the induction times of acylated derivatives increased; reducing power, radical scavenging activity against DPPH and hydroxyl radical decreased in the experimental test range was decreased.The dimethyl dicarbonate(DMDC) was synthesized by phase transfer catalyst, The product was purified through the thin-film evaporator. Chemical potential titration samples purity of 98%(DMDC,99.8 %), in line with national standards, need to further optimize the purification process.