Scientists hope that melanotropin-based drugs can overcome certain disadvantages of drugs that are currently available.
"Patients would have to take less amounts of a melanotropin-based drug and experience fewer side effects," Hruby said.
Hruby's team also managed to modify ligands so that they can cross the blood-brain barrier - an obstacle that prevents most substances circulating in the bloodstream from trespassing into the brain tissue. Since many melanocortin receptors are located in the brain, however, any drug that is supposed to act on these receptors has to cross the barrier.
Ligands developed by the UA scientists include a host of promising drug candidates. Some could be used as drugs to dampen appetite, others to restore erectile function and still others have been shown to promote tanning of the skin.
"People with fair skin complexion who are at greater risk from sunburn could benefit from a darker skin color that protects them from the sun in a natural way," said Hruby.
The UA scientists use structural design methods including structure-activity relationship analysis (SAR) to tailor compounds with the desired properties.
"We use computer-aided drug design to see what sorts of structures we can change without altering the basic structural features that are important for the molecule to exert its function," explained Hruby. His team uses in-vitro systems such as transfected cell lines to study the effect of the candidates on the cells' signal transduction mechanisms.
When given to animals in laboratory studies, some of the modified peptide ligands caused the animals to become less interested in feeding.'"/>