Variation Rule of Hydroxytyrosol Content in Olive Leaves

Hydroxytyrosol was extracted from 5 breeds of olive leaves from different tree ages by ultrasonic extraction using 90 % MeOH-H2O and analyzed by HPLC method.Simultaneously,the conversion trend of oleuropein into hydroxytyrosol was investigated from 10 breeds of olive leaves stored over 3 years.Results showed that:content of hydroxytyrosol in a growing year has one high peak period namely May and Jun.,and one low trough period,namely Nov.and Dec..Huge differences existed among different breeds.The content of hydroxytyrosol of 6 years age trees is higher than that of 18 years age.Erzhi No.8 olive leaves of 6 years age in May have the highest hydroxytyrosol content of 0.768 %,in contrary,6 years age Jiufeng No.6 olive leaves in Dec.have the lowest hydroxytyrosol content of 0.058 %.In leaves from 10 breeds of over 18 years age stored over 3 years,the content of oleuropein is greatly reduced,while the content of hydroxytyrosol is doubled.It means that a lot of oleuropein was degraded in hydroxytyrosol during the storage period.