PHILADELPHIA Researchers at the University of Pennsylvania and other institutions have identified an enzyme that appears to play a key role in bringing on sexual dysfunction in both men and women and a second molecule that can just as easily yank the offending enzyme out of commission. The findings, which carry the possibility of new treatments for sexual disorders, are scheduled to appear in two papers in the March 13 issue of Biochemistry, a peer-reviewed journal of the American Chemical Society, the worlds largest scientific society.
Led by Penn chemist David W. Christianson, the team found that the enzyme arginase can effectively short-circuit a biochemical pathway critical to male sexual arousal. But unlike remedies developed expressly for erectile dysfunction, which have proven disappointing in clinical trials with women, treatments that home in on arginase may offer hope for both sexes.
"There is intense interest in new targets for sexual dysfunction therapy," said Christianson, the Edmund and Louise Kahn Professor in the Natural Sciences. "Arginase should be a target in men and women alike, insofar as sexual dysfunction arises in both from circulation defects in the genitalia."
Offering the means to strike that target, Christianson and his co-authors pinpoint the amino acid derivative S-(2-boronoethyl)-L-cysteine, also known as BEC, as one of the tightest-binding arginase inhibitors ever identified. BEC joins another powerful arginase-blocking compound, (S)-2-amino-6-boronohexanoic acid, which was identified by Christianson in 1999.
In the chemical pathway that leads to sexual arousal in both sexes, arginase comes into play somewhat before phosphodiesterase V, the target molecule of Viagra which could present a new solution for the roughly 3 in 10 men for whom that medication is ineffective. Viagra has shown even less success in preliminary studies of female sexual dysfunction.