Antioxidant activity of hyaluronic acid investigated by means of chemiluminescence of equine neutrophil bursts and electron paramagnetic resonance spectroscopy.

The research article explores how hyaluronic acid (HA), a naturally occurring substance known for its anti-inflammatory properties, affects the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in horses. The study finds that HA can significantly decrease ROS/RNS, suggesting a potential therapeutic use in managing inflammatory diseases in horses.

Research Aims and Methods

• The researchers aimed to understand the impact of hyaluronic acid (HA), a gel-like substance that cushions joints and tissues, on oxidative stress in horses. Specifically, they investigated if HA can mitigate the releases of reactive oxygen species (ROS) and reactive nitrogen species (RNS), known as equine PMN respiratory bursts, that contribute to inflammation.
• A luminol-amplified chemiluminescence (LACL) test was performed to detect and measure the antioxidant activity of HA. The researchers also used electron paramagnetic resonance (EPR) spectroscopy to examine the direct antiradical activity of HA.

Key Findings

• The study found that HA scavenged the hydroxyl radical, a type of ROS, in a concentration-dependent manner, with the effectiveness ranging within HA concentrations of 0.16 to 2.5 mg/mL.
• HA also significantly inhibited the production of ROS/RNS, specifically superoxide anion, Tempol radical, and the ABTS(•+), at concentrations ranging from 0.62 to 2.5 mg/mL.
• The LACL test of stimulated equine neutrophils, a type of white blood cell, demonstrated that HA induced a significant reduction in ROS/RNS production, again in a concentration-dependent manner, from 1.25 to 5 mg/mL.
• The observed antioxidative effects of HA were further confirmed when l-Arginine was added to investigate the inhibition of peroxynitrite anion, a potent oxidant and nitrating agent.

Potential Therapeutic Application

• In addition to its known usage in human medicine, the study suggests that hyaluronic acid could also be used to lessen the oxidative stress generated by free radicals in horses’ peripheral blood mononuclear cells (PBMCs).
• The researchers recommend the aerosol administration of HA to horses with respiratory diseases, similar to its application method in human medicine. This avoids the need for systemic administration, focusing the therapeutic activity directly in the affected area, potentially providing an effective treatment for inflammatory airway diseases in horses.