Extraction Purification Of Pufas From Nitzschia Laevis And Study On Its Immunomodulatory Activity

Polyunsaturated fatty acids (PUFAs) plays an important role in the regulation of biological functions and prevention of a number of diseases involved heart and inflammatory diseases. The purification of EPA ethyl ester extracted from Nitzschia laevis using AgNO3-silica gel column chromatography was studied.The composition of fatty acids in N. laevis is C14:0, C16:0, C16:1, C18:1, C18:2, C18:3ω-3, C18:3ω-6, arachidonic acid (C20:4, ARA) and eocosapentaenoic acid (EPA, C20:5co-3). C18:3ω-3, C18:3co-6, ARA and EPA are the main PUFAs in N. laevis, accounted for0.92%,0.85%,7.19%and18.73%of TFA (total fatty acids), respectively.The lipid was extracted according to the modified method of Bligh and Dyer, then transesterification of it by the method of acid-catalyzed, which temperature is85℃for1.5h.AgNO3-silica gel column chromatography was used for purified PUFAs.6g of the AgNO3-silica gel was packed into chromatography column, use chloroform and acetone as the solvent. Over79%of the EPA content in the ethyl esters of total fatty acids extract from the N. laevis were recovered at purities exceeding97.15%, and the maximum acceptable fatty ester loading on the AgNO3-silica gel stationary phase is about3%(w/w).The effect of PUFAs on proliferation of murine splenocyte was carried in vitro by the method of MTT. The result shows that PUFAs could promote the proliferation of murine splenocyte, and the optimal dose is1μg/mL.The effect of PUFAs on immunomodulatory of normal mice and immunosuppressed mice are detected. After feeding mice by PUFAs, the index of immune organs, the phagocytotic functions of mononuclear macrophage, murine delayed type hypersensitivity (DTH) caused by sheep red blood cells (SRBC), and the ability of ahtibody production (tested by HC50) were determined in vivo. The results shows that PUFAs could promote the index of immune organs, phagocytitic function of mononuclear macrophage, DTH, and the ability of antibody production both on normal and immunosuppressed mice.