Research On The Isolation, Identification And Activity Of Avenacoside

Avena sativa.L.belongs to the gramineous Avena, which is rich in protein, unsaturatedfatty acids, vitamins and mineral and so on. So oat is famous as a kind of full nutritional valueof food. At the same time, oat is a health food with the efficacy of reducing blood lipid,treating constipation, lowering blood sugar and protecting cardiovascular.In recent years,researches about oat manily focused on the Oat β-glucan. However, the underlying functorelementand and molecular mechanism of some physiological activity (such as anti-tumoractivity) of oats remain largely unknown. It would be very intriguing to further investigate theactive ingredient in oats. As a result, we do a systematic study on the oat saponin.Three compounds were isolated from EtOH extraction of oat. They were purified byAB-8macroporous resin, MCI GEL and ODS reverse phase column. According to thephysicochemical method and1H-NMR,13C-NMR, the structure of these compounds wereidentified as：AvenacosideA:3-O-{[rhamnopyranosyl(1-4)][glucopyranosyl(l-2)]–glucopyran-osyl}26-O-glucopyranosyl furost-5-en-(25S)epoxy,26-diol;Avenacoside B:3-O-{[rhamnopyr-anosyl(1-4)][glucopyranosyl(l-3)-glucopyranosyl(1-2)]-glucopyranosyl}-26-O-glucopyranosl-furost-5-en-(25S)epoxy,26-diol;AvenacosideC:3-O-{[rhamnopyranosyl(1-4)]-glucopyranosy}-26-O-glucopyranosyl-furost-5-en-(25S)epoxy,26-diol. Avenacoside C is first reported ingramineae plants.We established the quantitative detection of oat saponin by HPLC. The Hypersil ODSC18columns (4.6×100mm,5μm)were used with the temperature of30°C and UV detectionat206nm. Gradient elution was performed with20%-50%acetonitrile in water for20minusing a flow-rate of1mL/min. Stability, precision and repeatability of this method meet thechallenge of analysis. And to the oat saponins this method has good isolation. So this methodwas used to analyse the saponins of oat. The content of total saponins in oatmeal is0.080%(dry matter basis). The amount of avenacoside A, B and C in oats (dry matter basis) are0.040%,0.023%,0.018%, respectively. Among these the content of avenacoside A is thehighest, which is about50%of the content of total saponins.MTT assay was used to assess antineoplastic activities of different parts of oat. The totalsaponins in oat showed strong activity in inhibiting tumor cell proliferation, while thepetroleum ether extraction part of oat, macroporous resin below30%ethanol elution part,macroporous resin95%ethanol elution part and oat β-glucan had minimal effects.Avenacoside A, B and C all showed obvious inhibition on both MCF-7and Hela cells.Avenacoside A was found to possess the strongest inhibitory against tumor cell proliferation.The IC50value of Avenacoside A against the breast cancer cells MCF-7and HeLa cells were59.10μg/mL and41.73μg/mL, respectively. The IC50value of Avenacoside B against thebreast cancer cells MCF-7and HeLa cells were76.32μg/mL and50.76μg/mL, respectively. While the IC50value of Avenacoside C against the breast cancer cells MCF-7and HeLa cellswere87.18μg/mL and54.27μg/mL, respectively.The saponins of oat had obvious inhibition on staphylococcus aureus, bacillus subtilis,escherichia coli and candida albicans, while they had no effect on salmonella and shigellabacteria, green bacillus, yellow aspergillus, red hair ringworm fungi and aspergillus. Amongthe three saponins, Avenacoside A showed the strongest inhibitory against the microorganism.The MIC values of Avenacoside A against staphylococcus aureus and bacillus subtilis were3.2mg/mL, to escherichia coli and candida albicans the MIC values were6.4mg/mL. Whilethe MIC values of Avenacoside B and C against these four kinds of microorganism were all6.4mg/mL.