he roots of the plant Pentalinon andrieuxii have been used by Mayans for years to treat infections from the parasite Leishmania, and researchers know now why: a compound from the plant, newly synthesized in the lab, reduces parasite load in infected mice.

“Pentalinonsterol could represent the next generation of small-molecule-mediated immunotherapy for visceral leishmaniasis,” Elizabeth Sharlow, a pharmacologist at the University of Virginia who did not participate in the research, toldChemical & Engineering News.

The disease, caused by Leishmania protozoa, is typically transmitted by sand fly bites. Victims suffer fever and weight loss, and can die if untreated. Up to 40,000 people die each year from visceral leishmaniasis. Although there are treatments available, most are expensive, come with side effects, and can lead to drug resistance.

In seeking alternatives to the typical medications, Abhay Satoskar of Ohio State University and his colleagues turned to traditional remedies used to treat a milder form of the disease, called cutaneous leishmaniasis. The researchers previously showed that an extract of P. andrieuxii, used by Mayan healers in Mexico, could harm the parasite in lab experiments, so they figured out how to synthesize the active compound.

In their latest report, published in ACS Infectious Diseases last month (August 15), the researchers wrapped their compound—called PEN—in liposomes and injected it into mice infected with L. donovani.“Liposomal PEN successfully rescued the impaired immune response of the L. donovani infected host by mediating a strong pro-inflammatory cytokine response,” Satoskar’s team wrote in its paper. “Additionally, it cleared parasite load in the liver, spleen, and bone marrow significantly better than controls, including the currently used clinical treatment, SSG.”

According to Chemical & Engineering News, the team is now designing an oral form of the medication and working to figure out its molecular mechanism.