s-adenosylhomocysteine and Malaria

Insecticidal resistance poses a major problem for malaria control programs. Mosquitoes adapt to a wide range of changes in the environment quickly, making malaria control an omnipresent problem in tropical countries. The emergence of insecticide resistant populations warrants the exploration of novel drug target pathways and compounds for vector mosquito control. Epigenetic drugs are well established in cancer research, however not much is known about their effects on insects. This study provides a simple protocol for examining the toxicological effects of 3-Deazaneplanocin A (DZNep), an experimental epigenetic drug for cancer therapy, on the malaria vector, Anopheles gambiae. A concentration-dependent increase in mortality and decrease in size was observed in immature mosquitoes exposed to DZNep, whereas the compound reduced the fecundity of adult mosquitoes relative to control treatments. In addition, there was a drug-dependent decrease in S-adenosylhomocysteine (SAH) hydrolase activity in mosquitoes following exposure to DZNep relative to control treatments. These protocols provide the researcher with a simple, step-by-step procedure to assess multiple toxicological endpoints for an experimental drug and, in turn, demonstrate a unique multi-prong approach for exploring the toxicological effects of water-soluble epigenetic drugs or compounds of interest against vector mosquitoes and other insects.

Topics: Adenosine; Adenosylhomocysteinase; Animals; Anopheles; Dose-Response Relationship, Drug; Female; Fertility; Insect Vectors; Insecticide Resistance; Insecticides; Malaria; Male; Mosquito Control; S-Adenosylhomocysteine; Survival Rate

A 4',5'-unsaturated 5'-fluoroadenosine inhibitor of S-adenosyl-L-homocysteine hydrolase (SAH hydrolase; EC 3.3.1.1), MDL 28842, was found to inhibit markedly the growth of Plasmodium falciparum in vitro and Plasmodium berghei in mice. Inhibition of P. berghei growth was associated with a large increase in the concentration of S-adenosyl-L-homocysteine (SAH) in the erythrocytes of the mice treated with MDL 28842. This increase in SAH was due apparently to inhibition of the mouse erythrocyte SAH hydrolase activity, because SAH hydrolase activity was undetectable in either P. berghei or P. falciparum isolated from infected erythrocytes, although enzyme activity was readily detected in mouse erythrocyte extracts. Therefore, MDL 28842 probably inhibits plasmodial growth indirectly by adversely changing the milieu of the host erythrocyte. SAH hydrolase represents a worthwhile target for the future development of potent inhibitors for the chemotherapy of malaria.

Topics: Adenosine; Adenosylhomocysteinase; Animals; Antimalarials; Erythrocytes; Hydrolases; Malaria; Molecular Structure; Plasmodium berghei; Plasmodium falciparum; S-Adenosylhomocysteine