Study On Extraction, Isolation And Antioxidant Activity Of Lignans Of Sesame Oil

Sesame (Sesamum indicum. L.) is an important oil crops, and it is one of the world’s oldest oil crops. China is a sesame-producing country, which is rich in natural resources. For the strong physiological activity, the extract of sesame lignans, will have a broad application prospects. This topic took sesame seeds as raw material, extracted sesamol, sesamin, sesamolin and sesaminol triglucosides, analysed its structure, and studied their antioxidant activity. Major tests and results are as follows:Firstly, we studied the assay method of the content of sesamin in sesame and sesame oil. Sesame and sesame oil was pretreated with dissolved in organic solvent, then HPLC was applied to make both qualitatively and quantitatively analysis of sesamin. Chromatographic conditions was as followings:chromatographic column, TSK gel ODS-100Z (4.6x250mm,5μm, Tosoh); the mobile phase, methanol/water was7/3(v/v) with the flow rate of1.0mL/min. It was detected at290ran, columm temperature35℃and the injection volume was20μL. It had high degree of separation, and good precision. It showed this result was suitable for the chromatography,Secondly, the extraction, purification and structure analysis of sesame lignans were studied. Taken sesame as raw material, methanol was used to extract sesamin and sesamolin from sesame oil, and the extraction was studied. The influences of single factors on extraction were studied. The effects on the yield of sesamin and sesamolin in different conditions such as extraction temperature, ratio of solid/liquid, extraction time and deposited time were researched. The optimization extraction parameters of sesamin and sesamolin by orthogonal design of Lg(3) were as follows:extracted at60℃for2.5h3times, the ratio of solid to liquid1:3.5and deposited time was5h.Sesamol, sesamolin and sesamin mononer were prepared by semi-preparative HPLC. The preparation conditions was as follows:chromatographic column, YMC-pack ODS-A (10x250mm,5μm, YMC). The mobile phase, methanol/water was8/2(v/v) with the flow rate of2.0mL/min. It was detected at290nm and the injection volume was0.1mL. By analysed the structures of mononers, it inferred that they were sesamin and sesamol, respectively. The purity of samples were all reached97%. Thirdly, the antioxidant activity of lignans in vitro was studied, it was showed that sesame lignans could scavenge free radicals (DPPH、OH). The total antioxidant capacity (TAC) and reduction ability of lignans enhanced with the increasing concentration in the range of0.1-1.0mg/mL. The antioxidative activities of lignans were also assayed by using the P-carotene/linoleate system. It showed that lignans also had inhibition effection the oxidation of linoleic acid.