NEW YORK (Reuters Health) - European researchers have created a carbohydrate-antioxidant hybrid polymer that can prolong the viability of sperm and enhance fertility.

The study, which is reported in the September 4th online issue of Nature Chemical Biology, involved the use of porcine semen, but the authors believe that the techniques could be easily applied to other mammals as well, including humans.

Sperm are known to be highly vulnerable to oxidative damage. The resultant drop in longevity can have important implications for artificial insemination techniques.

To protect sperm from such damage, Dr. Benjamin G. Davis, from the University of Oxford in the UK, and colleagues created a polymer that delivers the antioxidant vitamin E to sperm. The polymer featured a carbohydrate moiety designed to exploit a receptor on sperm that binds and internalizes galactose-containing molecules.

Using this polymer, the team was able to greatly increase vitamin E levels in porcine sperm, which was associated with decreased fatty acid degradation during oxidative stress.

The polymer-treated sperm had longer half-lives than untreated sperm, which, in turn, increased fertilization rates, the report indicates.

"Our results indicate that hybrid polymer delivery systems can prolong the functional viability of mammalian spermatozoa and improve fertility rates, and that our functionally guided optimization strategy can be applied to the discovery of active glycoconjugate ligands," the investigators conclude.

Nat Chem Biol. 2005 Oct;1(5):270-4. Epub 2005 Sep 4

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