Inhibitory effect of deltorphin-II on development of malaria in Plasmodium berghei-infected mice.

Background: Drug resistance has been one of the main obstacles in the fight against vector-borne infectious diseases. Among these diseases, malaria represents a serious public health challenge, mainly in the tropics, where vector-favourable climates are a crucial factor. Each of the various anti-malarial drugs currently used against this disease, such as quinolones, sulphonamides and artemisinins are inadequate and new strategies are required. Peptides are known to have a huge number of biological effects. Antimicrobial peptides (AMPs) have been proven to be effective against bacterial, fungal and viral infections. This study explored the effect of the peptide 'deltorphin-II' in Plasmodium berghei-infected mice.

Materials and methods: Mean percentage parasitaemia was calculated by studying infected erythrocytes after microscopic examination of 10⁴ erythrocytes from infected mice on days 4, 7, 10, 14 and 21 after infection in all groups. Results. Deltorphin-II shows maximum activity at a dose of 0.8 mg/kg/day from day 4 to day 21. Pre-treatment of infected mice with naltriben abrogates the deltorphin-II-mediated effect.

Conclusion: Deltorphin-II inhibits the development of malaria, most probably via activation of the δ₂ receptor.