Tuesday, June 30, 2009

Newest AIDS drug: Sugar?

A QUANTUM OF SCIENCE
Common polysaccharide prevents HIV infection in mice

Researchers at Meharry Medical College School of Medicine in Nashville recently reported that HIV-1 infections were blocked in mice by a surprising compound: cyclodextrin, a common cyclic sugar used extensively in food, pharmaceuticals and commercial products such as dryer sheets and Febreze.

The structure of cyclodextrin is a hollow ring, perfect for complexing hydrophobic molecules (such as fragrances, in the case of Febreze) and binding them tightly. This also makes cyclodextrin a good carrier molecule for pharmaceuticals, encapsulating drugs and aiding their delivery to different parts of the body. Surprisingly, the use of cyclodextrin in the food industry held the key to its role in preventing HIV infection. In the food industry cyclodextrins are employed for the preparation of cholesterol free products, allowing cholesterol to be sequestered inside the hollow ring of cyclodextrin and more easily removed from the food matrix.

Researchers have known for some time that there was a link between cholesterol and HIV infection. Cholesterol is an essential part of cell membranes, helping them stay fluid and permeable for normal trans-membrane traffic. Lipid rafts, a specialized structure rich in cholesterol, is required for HIV-1 to infect new cells. Though the research is still preliminary, cyclodextrin’s ability to bind and sequester cholesterol appears to play a role in preventing successful HIV infections. Trials in mice demonstrated a transient, reversible protective effect when female mice were challenged with HIV-laden semen. Similar experiments in primates have not fared as well, but issues with those studies have sparked several more extensive trials and the scientific community is abuzz with the possibilities.

Among the most exciting properties of cyclodextrin from a pharmaceutical standpoint is its safety. Discovered in 1891, cyclodextrins have been used for decades in foods and medicines. Its toxicity is extremely low, even when used in high dosages, and since it is composed entirely of sugar molecules there is little chance of complications or immune reactions. Only time will tell whether this humble molecule will find a new role in the prevention of HIV infections, but pharmaceutical giant Johnson & Johnson is already pursuing it as a therapeutic and prophylactic.

For more information:

http://www.the-scientist.com/templates/trackable/display/blog.jsp?type=blog&o_url=blog/display/55807&id=55807

© A Quantum of Science / P. Smalley (2009)
Reproduction with attribution is appreciation!