HEALTH NEWS

Study Title:

Carnosine and Cataracts

Study Abstract

Mildly denaturing conditions induce bovine α-crystallin, the major structural lens protein, to self-assemble into fibrillar structures in vitro. The natural dipeptide l-carnosine has been shown to have potential protective and therapeutic significance in many diseases. Carnosine derivatives have been proposed as potent agents for ophthalmic therapies of senile cataracts and diabetic ocular complications. Here we report the inhibitory effect induced by the peptide (l- and d-enantiomeric form) on α-crystallin fibrillation and the almost complete restoration of the chaperone activity lost after denaturant and/or heat stress. Scanning force microscopy (SFM), thioflavin T, and a turbidimetry assay have been used to determine the morphology of α-crystallin aggregates in the presence and absence of carnosine. DSC and a near-UV CD assay evidenced that the structural precursors of amyloid fibrils are polypeptide chain segments that lack stable structural elements. Moreover, we have found a disassembling effect of carnosine on α-crystallin amyloid fibrils. Finally, we show the ability of carnosine to restore most of the lens transparency in organ-cultured rat lenses exposed to similar denaturing conditions that were used for the in vitro experiments.

From press release:

Researchers are reporting evidence from tissue culture experiments that the popular dietary supplement carnosine may help to prevent and treat cataracts, a clouding of the lens of the eye that is a leading cause of vision loss worldwide.

In the new study, Enrico Rizzarelli and colleagues note that the only effective treatment for cataracts is surgical replacement of the lens, the clear disc-like structure inside the eye that focuses light on the nerve tissue in the back of the eye. Cataracts develop when the main structural protein in the lens, alpha-crystallin, forms abnormal clumps. The clumps make the lens cloudy and impair vision. Previous studies hinted that carnosine may help block the formation of these clumps.

The scientists exposed tissue cultures of healthy rat lenses to either guanidine — a substance known to form cataracts — or a combination of guanidine and carnosine. The guanidine lenses became completely cloudy, while the guanidine/carnosine lenses developed 50 to 60 percent less cloudiness. Carnosine also restored most of the clarity to clouded lenses. The results demonstrate the potential of using carnosine for preventing and treating cataracts, the scientists say.

Study Information

Francesco Attanasio‡, Sebastiano Cataldo§, Salvatore Fisichella, Silvia Nicoletti, Vincenzo Giuseppe Nicoletti, Bruno Pignataro§, Anna Savarino and Enrico Rizzarelli.
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Biochemistry,
2009 May
Department of Chemical Sciences, University of Catania, 95125 Catania, Italy.