Hydroxytyrosol as a potential ocular antioxidant

Abstract

Aims/Purpose: The influence of antioxidants on ocular processes has gained increasing importance in recent years due to their impact on eye health. One of the most promising antioxidants is hydroxytyrosol (HT), a natural compound found in olive leaves and olive oil. The purpose of this study is to develop an ocular insert containing HT for administration to the eye. The study aims to verify the absence of ocular toxicity of HT and formulate inserts incorporating this antioxidant.Methods: To evaluate potential ocular irritation, the hen's egg‐chorioallantoic membrane test (HET‐CAM test) was carried out. HT solutions at concentrations of 0.1, 1 and 10 mg/mL were prepared in phosphate buffer solution (PBS) with a pH of 7.4. Solutions of 0.1 N NaOH and 0.9% NaCl were used as positive and negative controls, respectively (1).Different inserts were formulated using polyvinylalcohol (PVA), hyaluronic acid (HA) and polyvinylpyrrolidone (PVP) as polymers with film‐forming capabilities and propylene glycol (PGL) as a humectant agent. The components were added gradually and stirred until a homogeneous solution was obtained. Finally, the solution was poured into a Petri dish and allowed to dry.Results: The HET‐CAM test demonstrated that HT solutions exhibited behaviour similar to the negative control (0.9% NaCl) and did not show any signs of irritation in terms of haemorrhage, lysis, or coagulation.Four formulations were developed with the following compositions: F1: PVA 3%, PVP 1%, HA 0.2%, PGL 2% and HT 0.1%; F2: PVA 2%, PVP 2%, HA 0.2%, PGL 2% and HT 0.1%; F3: PVA 4%, PVP 1%, PGL 2% and HT 0.1%; and F4: PVA 2%, PVP 2%, PGL 2% and HT 0.1%.Conclusions: Hydroxytyrosol can be considered non‐irritating to the eye, and PVA‐PVP‐HA ocular inserts have been developed. Further studies are necessary to select the appropriate hydroxytyrosol insert for ocular administration.