Polyphenol composition of olive leaves with regard to cultivar, time of collection and shoot type

Polyphenols in the olive have a relevant importance both in the physiology of the plant and the nutritional and biological value of its products. Olive leaves are increasingly important as a herbal remedy in western herbalism and a number of polyphenols have been shown to contribute to the healing properties of olive leaf teas. The present research is investigating the occurrence of such compounds in the leaves with regard to collection time, leaf age, shoot type and cultivar. The polyphenol composition of the leaves was determined by reversed-phase HPLC coupled with diode array and ESI-MS detection. The main extracted components were flavonol glycosides, flavone glycosides, and secoiridoids. A large variations in the total amounts of the different components was observed as function of the different cultivars and collection time (May, July, December). Leaf age and shoot type induce little or no variation in the concentration of most substances investigated. The maximal content of polyphenols and secoiridoids was found in December: in particular, the highest increase was observed for oleuropein, with a maximum value around 12 mg/g of leaves.