By Dr. Mallika Marshall

BOSTON (CBS) – Could we be closer to a birth control pill for men?

Scientists have been trying to develop one for decades but now they may have a new unusual lead: a plant extract, called ouabain, that was used by African warriors and hunters as a heart-stopping poison on their arrows.

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In high enough quantities ouabain can damage the heart, not really what you want in a birth control pill for men, but it can also disrupt a protein in sperm thought to be important for male fertility.

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So researchers manipulated the extract so it wouldn’t be toxic and tested it in rats, and found that it interfered with the sperm’s ability to swim.  If sperm can’t swim, they can’t fertilize an egg.

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The extract is not yet ready for prime time, but this could be encouraging news for men and women who think a male birth control pill is long overdue.

Dr. Mallika Marshall