Herbal Remedy May Help Protect Against Macular Degeneration
November 28, 2012

Rosemary Compound Shown To Help Fight Macular Degeneration In Mouse Model

April Flowers for redOrbit.com - Your Universe Online

Herbal remedies have been used for thousands of years in Asia and early European cultures. In recent years, Western medicine has shown a renewed interest in herbs for their medicinal qualities, and scientists are now isolating the active compounds in many, documenting their antioxidant and anti-inflammatory activities.

A new study led by the Sanford-Burnham Medical Research Institute (Sanford-Burnham) reports that carnosic acid, found in the herb rosemary, actually promotes eye health.

Led by Dr. Stuart A. Lipton, the team found that carnosic acid protects the retina from degeneration and toxicity in cell culture and in rodent models of light-induced retinal damage. This suggests that carnosic acid may have clinical applications for diseases of the outer-retina. These include age-related macular degeneration, which is the most common eye disease in the US.

There are likely many underlying causes of age-related macular degeneration, yet previous studies suggest that the disease might be slowed or improved by chemicals that fight free radicals. Free radicals are reactive compounds related to oxygen and nitrogen that can damage membranes and other cell processes.

The discovery that carnosic acid fights off free radical damage in the brain was made a few years ago by Lipton's team. In this latest study, the team investigated carnosic acid's protective mechanism in laboratory cultures of retinal cells.

They exposed the growing cells to hydrogen peroxide in order to induce oxidative stress, thought to be a factor contributing to disease progression in eye conditions such as macular degeneration and retinitis pigmentosa. The cells treated with carnosic acid triggered antioxidant enzyme production in the cells, in turn lowering the levels of reactive oxygen and nitrogen species (cell-damaging free radicals and peroxides).

Next, the team tested carnosic acid in an animal model of light-induced damage to photoreceptors, which are the part of the eye that converts light to electrical signals the brain can read, enabling visual perception. Rodents pre-treated with carnosic acid retained a thicker outer nuclear layer in the eye, as opposed to the untreated group. This indicates that the photoreceptors of the treated group were protected. The treated rodents also exhibited better electroretinogram activity, which is a measure of healthy photoreceptor function.

The team, which includes members from Nagase & Co, Inc., Allergan, Inc., and Iwate University, is continuing their research into carnosic acid.

"We're now developing improved derivatives of carnosic acid and related compounds to protect the retina and other brain areas from a number of degenerative conditions, including age-related macular degeneration and various forms of dementia," said Lipton, director of Sanford-Burnham's Del E. Webb Neuroscience, Aging, and Stem Cell Research Center and an active clinical neurologist.

Sanford-Burnham is a collaborative research facility dedicated to discovering the fundamental molecular causes of diseases and developing innovative therapies with major research programs in cancer, neurodegeneration, diabetes, and infectious, inflammatory, and childhood diseases.

The results of this study were published in a recent issue of the journal Investigative Ophthalmology & Visual Science.

Image 2 (below): Left: This shows control cells exposed to hydrogen peroxide. Right: This shows cells treated with carnosic acid are protected from hydrogen peroxide. Live cells are stained green, dead cells are stained red. Credit: Sanford-Burnham Medical Research Institute