Horseradish Enzyme Could Help Make Anti-Cancer Drugs

An enzyme in horseradish could make it easier to produce life-saving anti-cancer drugs, preliminary research suggests.

Agricultural Research Service scientists devised a method that uses the enzyme horseradish peroxidase in making cancer drugs known as chlorins. Currently, chlorins are made in a costly multi-step process. The new one-step method could save time and money.

ARS plant biochemist Franck Dayan made chlorins by combining the horseradish enzyme and a chemical cousin of chlorophyll. Plants use chlorophyll to turn light energy into food. But scientists doing research studies frequently turn to chlorophyll’s cheap, easier-to-use synthetic cousin, deuteroporphyrin IX. All plants use a form of peroxidase to make cell walls, but the horseradish version is extremely easy to extract.

Dayan is based at ARS’ Natural Products Utilization Research Unit in Oxford, Miss. He and ARS colleagues work to find potential new medical, food and industrial uses for chemicals naturally present in plants and other organisms.

Dayan came up with the new chlorin-making method--combining peroxidase and deuteroporphyrin IX--partly from a suggestion by medical researcher Nick Jacobs. Jacobs, with Dartmouth Medical School, initially recognized that deuteroporphyrin reacted with horseradish peroxidase and wondered aloud whether the tactic would yield chlorins.

Now, the University of Mississippi School of Pharmacy will test human cell cultures to ensure chlorins made this way are still effective photodynamic drugs.

Photodynamic compounds kill tumors when exposed to red light from tiny lasers. First, the drug is injected and carried through the body by blood proteins. Because cancer cells grow 10 times faster than healthy cells, they take in much more of the drug than healthy cells. After a few days, a physician shines a red laser light on the tumor. Nearby healthy cells-- transparent to the red light--are unaffected. But the chlorin molecules in the tumor cells are energized by red light and produce free radical oxygen molecules that destroy them.

Scientific contact: Franck E. Dayan, ARS Natural Products Utilization Research Unit, Oxford, Miss., phone (601) 232-1036, fax (601) 232-1035, fdayan@ag.gov.