Imagine the scene: Arms tensed, bow flexed, a hunter on the African savanna draws in a slow breath as his prey moves into view. Perhaps it’s an impala, maybe even an elephant or giraffe — beasts one might think too large for a single archer to fell. But the arrow’s tip has a secret weapon: the deadly poison ouabain. An extract of plants native to much of sub-Saharan Africa, the compound stops hearts, sometimes within just a few minutes.
Surprise: This heart-stopping poison could one day be our best option for a male contraceptive.
On a molecular level, ouabain is a disrupter. Throughout the body, membrane proteins control the movement of salts in and out of a cell, an exchange crucial to the cell’s survival and function. Ouabain molecules bind to the enzymes employed by the proteins in this process and prevent the exchange.
Ouabain traditionally affects cells in the heart, leading to cardiac arrest. Earlier this year, however, researchers announced that they had modified the ouabain molecule to target enzymes used by a type of protein found only in sperm. When the enzymes get gummed up and derail the cellular exchange process, sperm lose their ability to swim — and sperm can’t fertilize an egg if they can’t reach it. A preliminary study in rats indicated that the drug is both safe and effective.
