Monday, November 05, 2007

Drugs That Are Easier on the Environment

Continued from page 1

By Kevin Bullis

If certain types of new molecules must be synthesized from scratch, White's process could also cut down on the number of steps required during the drug-discovery or manufacturing process. As chemists synthesize new molecules, they have to think ahead about what chemical groups the end product must contain, and decide at what point in the synthesis process they must be added. That's because as the molecule becomes more complex at each step along the way, certain bonds become inaccessible. As a result, certain chemical groups can't be added late in the process. Yet incorporating these functional groups early in the process can make it much more complicated, requiring researchers to incorporate extra steps to protect the group from subsequent chemical reactions. White's catalyst makes it possible to add hydroxyl groups later in the process, potentially cutting more than five steps, Brickner says.

Joseph DeSimone, a professor of chemistry and chemical engineering at the University of North Carolina at Chapel Hill, says that by streamlining drug synthesis, White's catalyst could reduce the use of toxic metals and other toxic chemicals such as chlorine. The catalyst itself is based on iron, a benign metal. Other catalyst systems can make heavy use of toxic metals.

While the new catalyst should prove useful for a wide range of molecules, it's not a chemical panacea. It's specifically geared for modifying a certain type of bond in a specific way: researchers using White's catalyst can insert a hydroxyl group at specific carbon-hydrogen bonds.

In some cases, the sort of modifications possible with White's catalyst can already be made using enzymes. But White says that her catalyst is cheaper and can be used to modify many more types of molecules than enzymes.

"Any chemist who saw this paper would be considering applications," Brickner says.