Abstract
Purpose :
To determine the antioxidant and anti-inflammatory activity of crude extracts and their two major phenolic compounds (Oleuropein – OL and Hydroxytyrosol – HT), derived from the olive oil’s industry main environmentally hazardous by-product, the Olive Pomace (OP), in human corneal (HCE) and conjunctival (IM-ConjEpi) epithelial cells.
Methods :
Two OP extracts were produced: extract 1 (E1) by a conventional extraction, and 2 (E2) by a Design of Experiments extraction optimization. Their anti-inflammatory and antioxidant effects were tested in vitro in HCE and IM-ConjEpi cells. Cells were pre-treated for 2h with E1 (0.05-0.80 mg/mL) and E2 (0.005-0.400 mg/mL) and then stimulated with TNF-α (25 μg/ml) for 24h in the presence/absence of treatments. IL-1β, IL-6, IL-8 and IP-10 secretion was analysed by an immune bead-based array. Intracellular Reactive Oxygen Species (ROS) production was determined by H2DCF-DA dye assay in ultraviolet (UV)-B radiation-exposed cells in the presence/absence of treatment for 1h (with 1h pre-treatment). The effect of OL (5–300 μM), HT (1–100 μM) and their mixture (5 μM OL + 10, 25 or 50 μM HT) was also tested. Cells not exposed to TNF-α or UV-B, and vehicle-treated cells were used as control. Data were normalized to corresponding protein content.
Results :
TNF-α stimulated IP-10-secretion was significantly decreased in a dose-dependent way by E2 and HT in IM-ConjEpi and HCE cells, and by E1 and OL in IM-ConjEpi cells. IP-10 secretion was also decreased in HCE cells by 5 μM OL + 10 μM HT (P<0.001). IL-6 secretion was inhibited dose-dependently by HT and E1, and by 0.2 and 0.4 mg/mL of E2 in HCE (P<0.05). E1 (0.6 and 0.8 mg/mL), E2 (0.2 and 0.4 mg/mL) and 100 μM of HT decreased IL-8 secretion in HCE cells. IL-1β production in HCE was inhibited by E1 dose-dependently. UV-B stimulated ROS production was significantly inhibited in both cell lines by E1, E2, OL and HT dose-dependently and by 5 μM OL + 10 μM HT (P<0.01).
Conclusions :
Extracts from OP, an environmentally hazardous agro-industrial by-product, as well as their major phenolic compounds, HT and OL, may be used as therapeutic agent for inflammatory and oxidative-related ocular surface diseases. The results of this work consist an essential baseline for the treatment of these diseases in the future, while are paramount for the sustainable growth of related industries. Results are patent pending.
This is a 2021 ARVO Annual Meeting abstract.