Stability of oleuropein in olive leaves extracts and its chelating action to ferrous ions

The effect of different light sources, pH, temperature and time on stability of oleuropein was investigated regarding.The chelation of ferrous ions study was carried out as well.The experimental results showed that oleuropein was stable for light.It was degraded more easily under alkali surroundings than acid surroundings.According to TG-DSC analysis, it was found that oleuropein started to decompose at 232.3℃, and it was an exothermic process.With the time prolonging, oleuropein degradation rate increased.Compared with 38.1% at 4℃, it decomposed 95.24% at 25℃ within 27d due to β-glucosidase action insider it.When the enzyme in the extract was boiled to inactivation, oleuropein wouldn't be decomposed in 30d.In addition, in the experiments of chelating ferrous ions, the chelating rate of the extract was about 20% which significantly less than EDTA (95.24%) at concentration 1.2mg/mL.