The team designed ouabain alogs that are far more likely to bind to a protein subunit med a4 protein in sperm than to subunits found in heart tissue. By removing a sugar group from ouabain and also replacing its lactone group with a triazole group, the researchers created a derivative that is particularly good at zeroing in on a4 in sperm cells in rats. Once bound, it interferes with the cells’ ability to swim, which is essential to its role in fertilizing an egg, the scientists showed. (IANS)