Antioxidant properties of amniotic membrane: novel observations from a pilot study.

OBJECTIVE Amniotic membrane (AM) is used to manage various debilitated ocular surface conditions. The impact of oxidative stress and free radicals on the ocular surface is increasingly being recognized. Hyaluronic acid (HA) has anti-inflammatory properties and is abundantly present in AM. In this in vitro pilot study, we investigated the potential of AM for intrinsic free radical scavenging properties. METHODS Strips of AM were incubated in sealed tubes with hydrogen peroxide (H2O2). After being sonicated, uptake of reactive oxygen species (ROS) was measured by the Amplex Red Hydrogen Peroxide/Peroxidase assay. For comparison, 1630 kDA HA was used. RESULTS There was uptake of ROS by all AM samples, which decreased with increasing concentrations of H2O2. Mean ROS uptake for 5 different AMs at 1 hour was significantly greater for 50 μM (83%; SD 11.7, SEM 5.23) compared with 100 μM (67%; SD 20.48, SEM 9.16; p = 0.028; 95% CI 2.8-29.2). The HA comparison group showed similar uptake and trend. CONCLUSION This pilot study demonstrates that AM is able to remove ROS from its environment. Demonstrating total antioxidant capacity in AM provides evidence for use as a free radical scavenger. The antioxidant properties of AM and the contribution from HA require more research.