Isolation And Identification Of Oleiferasaponins With Anti-proliferative Activity Against Tumor Cells

Camellia oleifera Abel,a plant of Camellia L.,the specific woody oil plants,is distributed and cultivated widely in the central and south of China.Its seeds contain abundant amounts of unsaturated fatty acids,and used to extract edible oil.The remained tea seed waste was usually discarded or used as organic fertilizer or fuel.However,it should be noted that the tea seeds cake contained about 10% saponins.These saponins could be used as active compounds in agricultural and pharmaceutical application.They exhibited anti-oxidant activity,anti-hyperlipidemic activity,anti-fungal activity,anti-tumor activity and others.It has been reported that the seed cake of C.oleifera might contain about 30 types of saponins through LC-MS analysis.Whereas,thus far,only 6 saponins have been isolated and structurally identified,3 saponins namely oleiferasaponin A1,olerferasaponin B1 and oleiferasaponin B2.Furthermore,these three saponins were reported to exhibit significant cell protective or anticancer activity.Therefore,further investigation into the saponins from tea oil seed cake is meaningful for both agricultural and pharmaceutical applications.In this study,the seed cake of C.oleifera was extracted and fractionated by organic solvents.Silica gel,Sephadex LH-20,ODS column chromatography and semipreparative HPLC,HPLC purifications methods were applied for isolation of saponins.The structures of compounds were identified by extensive spectroscopic methods,including UV,IR,HR-ESI-MS,GC-MS,and 1D-and 2D-NMR.Finally the isolated compounds were tested for cytotoxic activities against human tumor cell lines by MTT method.This study reports the isolation and structural elucidation of six new saponins,namely oleiferasaponin C1(1),oleiferasaponin C2(2),oleiferasaponin C3(3),oleiferasaponin C4(5),oleiferasaponin C5(6),oleiferasaponin C6(7),and one known saponin,camelliasaponin B1(4),from an n-butanol extract of C.oleifera seed cake.In our assay,the inhibition activity of compounds 1-7 were tested in five human tumor cell lines,namely BEL-7402,BGC-823,MCF-7,HL-60 and KB.The results indicated that compound 3 did not show significant activity,compounds 1,2,4,5,6,and 7 showed obvious cytotoxicity,for example compounds 1 and 2,with IC50 values of 6.641 ?M(BEL-7402),12.766 ?M(BGC-823),5.567 ?M(MCF-7),7.930 ?M(HL-60),12.215 ?M(KB)for compound 1;IC50 values of 9.601 ?M(BEL-7402),13.558 ?M(BGC-823),11.223 ?M(MCF-7),4.590 ?M(HL-60),12.995 ?M(KB)for compound 2.The results provide certain theoretical basis for the anti-tumor efficacy of oleifera saponins and as the new raw material of anti-tumor drugs which provides the broader prospects for the effective development and utilization of C.oleifera seed cake.