Lipoxygenase activities in ripening olive fruit tissue

Extracts of ripening olive fruits (Olea europaea L. cv. Kalamata) were analyzed for the presence of lipoxygenase activity and for the content of phenolic compounds, which are lipoxygenase inhibitors. Two distinct lipoxygenase activities were identified by their pH optima and sensitivity to the inhibitor nordihydroguaiaretic acid (NDGA). Both activities were low during early ripening stages, and increased sharply between 57 and 94 days postanthesis, reaching a plateau at about 120 days. The content of phenolic compounds, mainly oleuropein, changed in the opposite way, suggesting their involvement in the regulation of the two lipoxygenase activities during the olive fruit development. The two lipoxygenase activities could have a role in fruit maturation and senescence.