LA JOLLA, Calif., November 27, 2012 – Herbs widely used throughout history in Asian and early European cultures have received renewed attention by Western medicine in recent years. Scientists are now isolating the active compounds in many medicinal herbs and documenting their antioxidant and anti-inflammatory activities. In a study published in the journal Investigative Ophthalmology & Visual Science, Stuart A. Lipton, M.D., Ph.D. and colleagues at Sanford-Burnham Medical Research Institute (Sanford-Burnham) report that carnosic acid, a component of the herb rosemary, promotes eye health.
Lipton’s team found that carnosic acid protects retinas from degeneration and toxicity in cell culture and in rodent models of light-induced retinal damage. Their findings suggest that carnosic acid may have clinical applications for diseases affecting the outer retina, including age-related macular degeneration, the most common eye disease in the U.S.
Age-related macular degeneration
Age-related macular degeneration likely has many underlying causes. Yet previous studies suggest that the disease might be slowed or improved by chemicals that fight free radicals—reactive compounds related to oxygen and nitrogen that damage membranes and other cell processes.
Lipton’s team first discovered a few years ago that carnosic acid fights off free radical damage in the brain. In their latest study, Lipton and colleagues, including Tayebeh Rezaie, Ph.D. and Takumi Satoh, Ph.D., initially investigated carnosic acid’s protective mechanism in laboratory cultures of retinal cells.
The researchers exposed the cells growing in the dish to hydrogen peroxide in order to induce oxidative stress, a factor thought to contribute to disease progression in eye conditions such as macular degeneration and retinitis pigmentosa. They found that cells treated with carnosic acid triggered antioxidant enzyme production in the cells, which in turn lowered levels of reactive oxygen and nitrogen species (cell-damaging free radicals and peroxides).
Rosemary’s therapeutic potential
Lipton, Rezaie, Satoh and colleagues next tested carnosic acid in an animal model of light-induced damage to photoreceptors—the part of the eye that converts light to electrical signals, enabling visual perception. As compared to the untreated group, rodents pre-treated with carnosic acid retained a thicker outer nuclear layer in the eye, indicating that their photoreceptors were protected. The carnosic acid-treated rodents also exhibited better electroretinogram activity, a measure of healthy photoreceptor function.
What’s next for 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.
This research was funded by the U.S. National Institutes of Health: Eunice Kennedy Shriver National Institute of Child Health & Human Development grant P01 HD29587; National Institute of Environmental Health Sciences grant P01 ES016738; National Institute of Neurological Disorders and Stroke grant P30 NS076411; National Eye Institute grant R01 EY05477
The study was co-authored by Tayebeh Rezaie, Sanford-Burnham; Scott R. McKercher, Sanford-Burnham; Kunio Kosaka, Nagase & Co., Ltd.; Masaaki Seki, Sanford-Burnham; Larry Wheeler, Allergan, Inc.; Veena Viswanath, Allergan, Inc.; Teresa Chun, Allergan, Inc.; Rabina Joshi, Sanford-Burnham; Marcos Valencia, Sanford-Burnham; Shunsuke Sasaki, Iwate University; Terumasa Tozawa, Iwate University; Takumi Satoh, Sanford-Burnham and Iwate University; and Stuart A. Lipton, Sanford-Burnham.
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About Sanford-Burnham Medical Research Institute
Sanford-Burnham Medical Research Institute is dedicated to discovering the fundamental molecular causes of disease and devising the innovative therapies of tomorrow. The Institute consistently ranks among the top five organizations worldwide for its scientific impact in the fields of biology and biochemistry (defined by citations per publication) and currently ranks third in the nation in NIH funding among all laboratory-based research institutes. Sanford-Burnham utilizes a unique, collaborative approach to medical research and has established major research programs in cancer, neurodegeneration, diabetes, and infectious, inflammatory, and childhood diseases. The Institute is especially known for its world-class capabilities in stem cell research and drug discovery technologies. Sanford-Burnham is a U.S.-based, non-profit public benefit corporation, with operations in San Diego (La Jolla), California and Orlando (Lake Nona), Florida. For more information, news, and events, please visit us at sanfordburnham.org.