doi:10.1038/nindia.2013.155 Published online 25 November 2013
Researchers have developed a nanosized drug carrier based on a natural polysaccharide for delivering antimalarial drug chloroquine . They found that chloroquine conjugated to nanoparticles was more effective in killing malaria parasites in mice than free chloroquine. Chloroquine-loaded nanoparticles potentially could be used to kill chloroquine-resistant malaria parasites in humans.
Studies have shown that malaria parasites have grown resistant to antimalarial drugs such as chloroquine, sulfadoxine-pyrimethamine and artemisinin. There is thus a need to develop alternative therapies. Biodegradable and biocompatible polymeric nanoparticles are good drug carriers that are known to enhance the efficacy of drugs. One such natural polymer is chitosan, a polysaccharide found in marine crustaceans, insects and fungi. However, its potential to carry chloroquine had not been studied previously.
To assess the antimalarial drug-carrying potential of chitosan, the researchers synthesized chloroquine-loaded chitosan nanoparticles (nanochloroquine) and investigated their chloroquine-delivering potential and how effective they were in killing Plasmodium berghei, a parasite that causes malaria in mice. They compared the malaria-parasite-killing efficacy of nanochloroquine with that of free chloroquine in malaria-infected mice.
The infected mice initially had a parasite load of 26.47 per cent. After treatment by chloroquine and nanochloroquine, the parasite load decreased to 8.33 and 0.8 per cent, respectively. Malaria infection in the mice depleted their antioxidant enzyme levels, thereby increasing the levels of reactive oxygen species such as superoxide ions. These reactive oxygen species damage DNA, inducing cell death.
Nanochloroquine enhanced the levels of antioxidant enzymes and reduced the levels of reactive oxygen species more than free chloroquine. The nanochloroquine also protected DNA from parasite-induced damage, preventing subsequent cell death.
"Nanochloroquine might be used as a potential therapeutic agent against malarial infection," says Somenath Roy, a senior author of the study.