One of the compounds found in P. harmala, vasicine (peganine), has been found to kill Leishmania donovani, a protozoan parasite that can cause potentially fatal visceral leishmaniasis.
It can be used to treat bovine East Coast fever protozoa in vitro, along with the only other substance known - Peganum harmala.
Peganum Harmala contains Harmaline, which is a strong MAO-inhibitor, and it is therefore often used as a 1st component in Ayahuasca ceremonies in order to inhibit the metabolisation of an orally-administered DMT molecule (2nd component).