A poisonous snake's venom may help scrub out tough bloodstains, chemists say.

Snake venom contains enzymes to stop blood from clotting. Researchers in California were interested in using the compounds to treat heart attacks and strokes.

As a side project, biochemist Devin Iimoto of Whittier College in California assigned two undergraduates to test if using the enzymes could remove bloodstains better than detergent alone.

Clots make blood a stubborn stain

Bloodstains are often difficult to remove from clothes because of the clotting.

Scientists can buy the Florida Cottonmouth venom commercially since it is used to produce antivenin.

The researchers isolated a non-toxic enzyme from the venom. They say it likely facilitates the spread of toxin by hampering the body's attempt to seal wounds.

Out, damned spot

In the preliminary tests, the team applied the enzyme to spots of blood that air-dried for one hour on pieces of white denim.

They laundered the samples with untreated bloodstained controls in a washing machine with common laundry detergent and warm water.

After drying, the venom-treated swathes were "noticeably fainter," the researchers said Monday at the American Chemical Society's national meeting in Anaheim, Calif.

They said an earlier British study that used a different enzyme for a shorter period was unsuccessful in removing bloodstains.

The U.S. researchers are quantifying their results and they plan to test the enzyme in different water temperatures and with other enzymes in the hopes of removing stains completely.