Research is paving the way for potentially greener and more efficient production of a vital cancer-fighting drug.
First isolated from the bark of the Pacific yew in 1967, the drug paclitaxel - better known as Taxol - has since been made by synthetically modifying an intermediate substance isolated from yew needles using toxic solvents or by fermenting cell cultures.
The new method worked out by Michigan State University (MSU) chemist Kevin Walker employs natural enzymes instead. "Pharmaceutical companies could reduce the steps involved in making Taxol," he said, "while cutting chemical byproducts".
Walker, assistant professor of chemistry, biochemistry and molecular biology, studies enzymes that assemble the Taxol molecule in Taxus plants.
"This process is like painting from a palette," Walker said. "We can add select colours to the palette from which the enzyme chooses, so the molecule can be crafted in a variety of ways. The enzyme does all the work," he said.
"A plant enzyme can do in one step what traditional synthetic construction does in multiples steps. Under our process, the construction of Taxol uses a biological assembly line where each enzyme does its job to create the final product.
"Particular enzymes on the assembly line can attach slightly different components on the molecular frame to create new-generation Taxol molecules. This can lead to more effective drug variants and eventually better health care treatment."
Taxol "is definitely a frontline drug and is used to treat many cancers", including those of the breast, lung, head and neck, said Barbara Conley, who heads the MSU haematology and oncology division, said an MSU release.
The findings were published in the Journal of the American Chemical Society.