Compound obtained from leaves of jaborandi acts against schistosomiasis parasite

In tests with mice, epiisopiloturine was effective against juvenile and adult forms of Schistosoma mansoni. Researchers are investigating its mechanism of action to try to boost its therapeutic effect.

By Karina Toledo

Agência FAPESP – Epiisopiloturine, a compound obtained from the leaves of Maranham jaborandi (Pilocarpus microphyllus), has been found to work against the juvenile and adult forms of Schistosoma mansoni, the parasite that causes schistosomiasis, in preclinical trials.

The chemical stability of epiisopiloturine was tested at the University of São Paulo’s São Carlos Physics Institute (IFSC-USP) in Brazil during postdoctoral research conducted by Ana Carolina Mafud and supervised by Yvonne Mascarenhas, a professor at IFSC-USP. The research is supported by FAPESP.

The results were recently published in the journal PLoS Neglected Tropical Diseases.

“In partnership with SUS, Brazil’s national health system, we’re evaluating the compound’s efficacy and safety as a herbal drug,” Mafud said. “It may also be possible to make small modifications to create more potent synthetic versions of the molecule that would be more interesting for the pharmaceutical industry.” Mafud and colleagues are partnering with the Federal University of Piauí’s Biodiversity & Biotechnology Research Center (Biotec-UFPI), and the Adolfo Lutz Institute (IAL) in São Paulo State.

“A company called Centroflora in Piauí already extracts pilocarpine on an industrial scale. Pilocarpine is also present in jaborandi leaves and is used to treat glaucoma. The industrial process generates a large amount of liquid waste, for which there are no adequate disposal sites,” Mafud said.

Researchers at Biotec-UFPI led by José Roberto de Souza de Almeida Leite, a professor at the institution, decided to investigate whether this industrial waste produced by Centroflora contained other substances with therapeutic potential. They found that 70% of the liquid consisted of epiisopiloturine.

The molecule’s 3D structure was then identified by Mascarenhas and her group at IFSC-USP. “Like pilocarpine, epiisopiloturine is also an alkaloid. They have similar structures but their biological action is different,” Mafud explained.

The extraction and purification of epiisopiloturine, as well as the compound’s 3D structure, were described in an article published by PLoS One in 2013.

In vitro testing of epiisopiloturine’s activity against various parasites at the Butantan Institute in São Paulo showed activity against S. mansoni in all stages of its life cycle. The experiments were performed by Josué de Moraes, then a postdoctoral researcher and now a professor affiliated with the Neglected Diseases Research Center at the Guarulhos School of Sciences (FACIG).

Praziquantel, the main drug currently used to control schistosomiasis, is effective only against adult worms. Moreover, although it improves the patient’s condition, it cannot cure the disease or interrupt its transmission. Other drawbacks of praziquantel include high liver toxicity and the lack of a pediatric formulation, hindering the treatment of children, the main age group affected by the disease.

The results of the tests performed at the Butantan Institute were described in an article published by the journal Current Medicinal Chemistry in 2012.

Animal model

Before embarking on tests in mice, researchers at the University of Brasília (UnB) performed in vitro experiments to evaluate the toxicity of epiisopiloturine to mammalian cells. Researchers at IFSC-USP completed the data by evaluating other variables and concluded that the compound is safe and has the potential to become a medical drug.

“We analyzed all fragments of the molecule’s structure to see whether any functional group might have mutagenic or toxic effects,” Mafud said. “We also performed solubility, stability, absorption, metabolism and excretion studies to determine the best way to administer the substance to animals.”

The compound was orally administered to mice in a single dose approximately 49 days after infection by the parasite.

“The worm has a complex life cycle and can live in the human organism in three different stages – as eggs, juveniles and adults. Epiisopiloturine was effective in all stages, without significant in vitro or in vivo toxicity,” Mafud said.

The only drawback is that for epiisopiloturine to be effective, it must be administered in a far higher dose than praziquantel (150 milligrams per kilogram as opposed to 5 mg/kg), which does not make it attractive to the pharmaceutical industry.

The researchers from Biotec-UFPI are currently testing a ten-day treatment with lower doses in mice at IAL. Studies with larger animal models such as rabbits and dogs will be performed with funding from SUS to evaluate the use of the compound as a herbal drug.

Mafud is also investigating the compound’s mechanism of action as part of her postdoctoral research. This knowledge may pave the way for research designed to modify the molecule’s structure and make it more potent. This part of the work is being performed at the Center for Research and Innovation in Biodiversity and Drug Discovery (CIBFar), one of the Research, Innovation and Dissemination Centers (RIDCs) supported by FAPESP.

Schistosomiasis affects almost 240 million people worldwide, according to the World Health Organization (WHO), and is the most deadly verminosis. More than 700 million people live in areas where schistosomiasis is endemic, located mainly in tropical and sub-tropical regions, in poor communities without potable water and adequate sanitation.

Symptoms of the acute stage of infection include itching, dermatitis, fever, loss of appetite, coughing, diarrhea, nausea, vomiting and weight loss. During the chronic phase, episodes of diarrhea may alternate with periods of constipation.

Symptoms of the worst form of the disease include an enlarged liver and cirrhosis, an enlarged spleen, hemorrhages caused by rupture of esophageal varices, and a swollen belly due to extravasation of plasma fluid to the peritoneal cavity.