The Principal Investigator

An antifungal compound produced by a species of tropical seaweed also attacks the malaria parasite, Plasmodium falciparum, scientists reported on Monday at the annual meeting of the American Association for the Advancement of Science (AAAS). If researchers can replicate their findings in animal and human tests, the compound could lead to the development of more effective malaria drugs in the future.

In 2009, there were an estimated 225 million cases of malaria worldwide, and 781,000 deaths caused by the disease, according to the World Health Organization’s 2010 Malaria Report – the most recent data available. Even though these statistics represent a drop in the numbers of malaria cases and deaths from previous years, health experts worry about the emergence and spread of strains of malaria that are resistant to artemisinin – the most effective antimalarial to date – could reverse these gains if new agents are not discovered soon.

Julia Kubanek, of the Georgia Institute of Technology, was leading a team of researchers interested in how marine plants and animals protect themselves from infection, when they came across the seaweed Callophycus serratus, which lives on tropical coral reefs in waters off Fiji. The red algae produced a class of compounds known as bromophycolides, which protected it from the growth of Lindra thalassiae, a common marine fungus. Biomedical screening revealed bromophycolides had antimalarial properties.

Science Now describes the mechanism Kubanek’s group believes bromophycolides are using to kill off the malaria parasite: “Malarial parasites infect red blood cells and they thrive on hemoglobin, the body’s oxygen-carrying molecules,” but as they break hemoglobin down, “they release heme, a pigment that is toxic to them.”  As Kubanek reported on Monday, early studies suggest bromophycolide interferes with the parasite’s natural response to heme, resulting in the poisoning of the parasite. It’s a strategy similar to that taken by the drug chloroquine – an early generation antimalarial that Falciparum has developed a resistant to in parts of the world where malaria is endemic.

“We are still working on this area, but so far we know that bromophycolides are toxic to Plasmodium falciparum, including at least one chloroquine-resistant strain, at sub-micromolar concentrations,” Kubanek said, according to Guardian. “That is not whopping potency – artemisinin is more effective. But it is promising as a lead molecule and we hope to eventually design a more potent and selective derivative.” The researchers now plan to test the effectiveness of the compound in mice infected with malaria.

The World Health Organization has been increasingly focused on the issue of antimicrobial resistance worldwide. In January, the agency launched a global initiative to stop the spread of artemisinin-resistant malaria by increasing surveillance, improving access to diagnostics and greater investment in artemisinin-related research. In April, the WHO plans to introduce several policy measures to fight the spread of antimicrobial resistance worldwide.

Regular aerobic exercise during late adulthood can help improve memory and decrease one’s risk of dementia, according to a study published Monday in the Proceedings of the National Academy of Sciences.

Previous studies show that exercise can lead to new cell growth in regions of the brain, boosting function, but whether similar growth takes place in the hippocampus, a part of the brain involved in memory that tends to decline in old age, remained unclear.

To help answer this question, researchers put 120 sedentary adults in their 60s to work – half of the group took to the track where they walked for 40 minutes, three days a week, while the others participated in a lower intensity stretching regimen. Both groups participated in the program for one year.

Although hippocampal regions of two groups were similar at the beginning of the exercise program, MRI scans revealed that after one year the hippocami of walkers grew by about 2 percent whereas seniors exposed only to stretching activities experienced a shrinkage in this same region of about 1.4 percent over the same period.

Additional analysis revealed that the greater the fitness progress made by the adults over the course of the trial, the greater the growth in the hippocampus. Blood tests also confirmed that the walkers had higher levels of the protein BDNF, known to be involved in the growth of new brain cells, corresponded with the changes in hippocampal volume.

“We think of the atrophy of the hippocampus in later life as almost inevitable,” with an estimated 1 to 2 percent lost annually, Kirk Erickson, professor of psychology at the University of Pittsburgh and lead author of the study said in a university press release. “But we’ve shown that even moderate exercise for one year can increase the size of that structure. The brain at that stage remains modifiable.”

The participants were also given a spatial memory test before, during and after the exercise period. Both groups became faster at responding to the test and more accurate between the first and last testing sessions for aerobic exercise and stretching. However, researchers did find that participants who had larger hippocampi at the start and completion of the program had better performances in the memory tests, leading them to believe that growth in the hippocampus resulting from exercise “should translate into improved memory function.”

“The results of our study are particularly interesting in that they suggest that even modest amounts of exercise by sedentary older adults can lead to substantial improvements in memory and brain health,” Art Kramer, director of the Beckman Institute at the University of Illinois and the senior author said, according to the press release. “Such improvements have important implications for the health of our citizens and the expanding population of older adults worldwide.”