What if the New Antimalarial Drugs Came from the Sea?

A study led by Xavier Fernández-Busquets, researcher of the joint IBEC-ISGlobal Nanomalaria unit, shows that certain sugar molecules (sulfated polysaccharides) obtained from marine organisms inhibit the growth of Plasmodium falciparum, the malaria-causing parasite by inhibiting its capacity to invade red blood cells. The results, published in Scientific Reports, open new avenues for the development of antimalarial drugs against which Plasmodium does not seem to develop resistance.  

When the malaria parasite enters the blood, it invades liver cells in order to produce thousands of merozoites (a stage in its life cycle). These merozoites are then released back into circulation, where they invade red blood cells and manage to evade immune surveillance. It is known that some polysaccharides such as heparin can block adhesion to and invasion of red blood cells by merozoites. However, heparin has not been therapeutically exploited due to its potent anticoagulant activity.

In this study, the authors explored the antimalarial activity of heparin-like sulfated polysaccharides extracted from sea cucumbers, red algae and marine sponges. They found that these compounds significantly inhibit P. falciparum growth, even at concentrations where their anticoagulant activity is low. Furthermore, most of the tested compounds improved the survival of mice infected with another Plasmodium species. In fact, in one of the treated animals they detected the presence of parasite-specific antibodies, which suggests that the retarded invasion of red blood cells may favor the development of an immune response against the parasite.   

“Our results indicate that these compounds not only have antimalarial activity, but can also potentiate immune responses against the parasite” says Dr. Busquets. In addition, the authors point out that, given the difficulties in selecting heparin-resistant parasites in the laboratory, these results place marine-derived sulfated polysaccharides as alternative candidate molecules that deserve careful exploration.   

The study also involved the participation of researchers from the University of Barcelona's Institute of Nanoscience and Nanotechnology (IN2UB) and the Federal University of Rio de Janeiro, Brazil.  

Reference:

Marques J, Vilanova E, Mourão PA, Fernàndez-Busquets X. Marine organism sulfated polysaccharides exhibiting significant antimalarial activity and inhibition of red blood cell invasion by Plasmodium. Sci Rep. 2016 Apr 13;6:24368