Separation And Determination Of Saponin Components In Soybean Germs

Soyasaponin is one of the important components in soybean, which has some important bioactivities and physiological activities, such as reducing plasma cholesterol and guarding against atherosclerosis. It has great economic potential based on its medical functions as well as industrial functions, such as vesicant, emulsifier, stabilizer and flavor additive.In this thesis, some single purified soysaponins have been isolated and prepared from soybean hypocotyls by high performance liquid chromatography with photodiode array detector after aqueous extraction, purification by macro porous absorbent resins, cation exchange resins and gel permeation chromatography. Their purities were analyzed by HPLC with ELSD. Their structures have been elucidated by LC-MS. The internal standard method and spectrophotometric method were established for the quantitative assay of soyasaponins. The main results are shown as follows:At first, five single soysaponins with high-purity have been isolated from soybean hypocotyls. They have been elucidated as soyasaponin Aa, Ab, Ba, Bb and Be by LC-ESI/MS. Their proportions of chromatogram peak area were all more than 95%, analyzed by HPLC with ELSD.The quantitative method of soyasoponin Ab and Bb by ELSD-HPLC were established using equilenin as internal standard.. The regression equation of soyasoponin Ab was lgy = 1.6658lgx-0.7123, R2 = 0.9995. The recycle rate was 98.2%～100.3%. The regression equation of soyasoponin Bb was lgy = 1.8734lgx-0.9667, R2 = 0.9998. The recycle rate was 97.7%～100.2%. The results showed that the method was sufficiently accurate for assays in series. The content of group A, group B soyasaponins and total soyasaponins were calculated by the two single purified soyasaponins.A spectrophotometric method was established for the quantitative determination of the total content of saponins in soybean germs. With the vanillin-perchloric acid as chromogenic reagent, glacial acetic acid as solvent system, acid hydrolyzed soyasaponin Bb as standard, aglycones in soyasaponins were determinated at the optimum wavelength of 563 nm. There was a good linear relationship between the absorbance and the quantity of aglycones. The regression equation was y = 12.331x-0.0555, R2 = 0.9985, the recycle rate was 95.48%～102.93%. The applied method was sufficiently sensitive, precise and accurate for determination of total soyasaponins in soy germs or related products. The method is characterized by good linearity over the measurement range of (0.0035-0.0247)μmol.ml?1.