The good side of pro-oxidative action of plant polyphenols: an action mechanism for the pro-apoptotic activity

Olive oil production generates huge quantities of waste in the form of olive mill waste waters (OMWW), which may have great environmental impact because of their high phytotoxicity, toxicity against aquatic organisms and possible suppression of soil microorganisms. However, this by-product is characterized by a high organic component including numerous interesting compounds, such as polyphenols with valuable biologic properties. Many studies were carried out in order to recover polyphenols by different strategies or to use the aqueous extract of OMWW for the preparation of high value added products. The objective of this work in the within of the EU project BIO-OLEA "Utilization of biophenols from Olea Europea products - Olives, virgin olive oil and olive mill wastewater" was to obtain scientific evidences about the biological activity of several compounds present in OMWW, their action mechanisms and putative utilizations. Polyphenols usually present in OMWW were considered and the effect of each compound was valuated on human keratinocyte cell culture exposed with different timing, to ultraviolet -A rays (UVA) that are known as one of the most important etiological factors in the development of skin disorders such as immunosuppression, photo-aging and photo-carcinogenesis, and cancer. This activity was aimed to find out the possible uses of OMWW based products by defining the biological activity of specific polyphenols present in OMWW. Understanding basic action mechanisms enables us to supply the general knowledge on the biological properties of polyphenols present in the OMWW matrix and to contribute to the technological information useful to enable the producers to manage the OMWW. OMWW represent a rich source of phenol compound with high antioxidant activity and valuable other biological properties. Here it is proposed that some of these polyphenols have the ability to trigger the apoptosis pathways mainly in UVA-damaged cells, via ROS increase, as an action mechanisms behind their protective effect. The implementation of olive oil production by means of different technologies aimed to preserve the OMWW quality and safety could allow the integration of the recovery and utilization of this by-product, in the olive oil production process.