title: Antioxidant properties of amniotic membrane: novel observations from a pilot study.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Tennent Institute of Ophthalmology, Glasgow, United Kingdom. Electronic address: davidlockington@hotmail.com.
authors.forename: David
authors.initials: D
authors.lastname: Lockington
authors.affiliation: Tennent Institute of Ophthalmology, Glasgow, United Kingdom.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Agarwal
authors.affiliation: Department of Statistics and Modelling Science, University of Strathclyde, Glasgow, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Young
authors.affiliation: Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Muriel
authors.initials: M
authors.lastname: Caslake
authors.affiliation: Tennent Institute of Ophthalmology, Glasgow, United Kingdom.
authors.forename: Kanna
authors.initials: K
authors.lastname: Ramaesh
mesh_terms: D000650:Amnion / Q000187:drug effects / Q000502:physiology*; D000975:Antioxidants / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D010865:Pilot Projects; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D016877:Oxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide