Study of the amount of oleuropein level in the leaves of olive varieties cultivated in Khorramabad (Iran)

Background: Oleuropein (OE) is the most abundant biophenol compounds in olive leaves and its healthy effects as a strong antioxidant is well known. The oleuropein level in olives depends upon cultivated variety, climate, place, time and the method of extraction. In Lorestan province, many varieties of olive have been cultivated that the study of OE level in their leaves, as whilst sources of this material, is of great value. Materials and methods: In this work, the leaves of 13 varieties of cultivated olive in a research station in Khorramabad were collected. OE and related compounds were extracted in two 30 min successive stages in an ultrasonic bath using 30: 70 water/ethanol as solvent. For quantitative determination of OE in the extracts, a HPLC method with C-8 column was used. Results: The extraction method efficiently extracted OE from olive leaves and optimization of the HPLC method resulted in an appropriate separation and quantitation of the sample components. Study of the OE concentrations in 13 varieties of olive leaf samples indicated that the difference in OE level between olive varieties is quite significant. The minimum and maximum OE levels were observed in Kalamon variety, with 112. 9 mg/g, and Sevillana variety, with 235. 7 mg/g, respectively. Conclusion: Olive leave, is a cheap and wealth source of OE and according to the results of this work one can select the varieties to be used for the preparation of medicines containing high levels of this important antioxidant