nogalamycin and Malaria--Falciparum

Plasmodium falciparum has been becoming resistant to the currently used anti-malarial drugs. Searching for new drug targets is urgently needed for anti-malarial development. DNA helicases separating double-stranded DNA into single-stranded DNA intermediates are essential in nearly all DNA metabolic transactions, thus they may act as a candidate for new drug targets against malarial parasites.. In this study, a P. falciparum 5' to 3' DNA helicase (PfDH-B) was partially purified from the crude extract of chloroquine- and pyrimethamine-resistant P. falciparum strain K1, by ammonium sulfate precipitation and three chromatographic procedures. DNA helicase activity of partially purified PfDH-B was examined by measuring its ability to unwind. Partial purification and characterization of 5'-3' DNA helicase of P. falciparum was successfully performed. The partially purified PfDH-B does not need a fork-like substrate structure found in P. falciparum 3' to 5' DNA helicase (PfDH-A). Interestingly, nogalamycin was the most potent anthracycline inhibitor for PfDH-B helicase activity and parasite growth in culture. Further studies are needed to search for more potent but less cytotoxic inhibitors targeting P. falciparum DNA helicase in the future.

Topics: Anthracyclines; Antimalarials; DNA; DNA Helicases; Humans; Malaria, Falciparum; Nogalamycin; Plasmodium falciparum

Topics: Adenosine Triphosphatases; Antimalarials; Daunorubicin; DNA Helicases; DNA Mismatch Repair; DNA, Protozoan; Drug Resistance; Ethidium; Etoposide; Malaria, Falciparum; Molecular Docking Simulation; MutL Protein Homolog 1; Netropsin; Nogalamycin; Plasmodium falciparum; RNA, Double-Stranded

Human malaria parasite infection and its control is a global challenge which is responsible for ~0.65 million deaths every year globally. The emergence of drug resistant malaria parasite is another challenge to fight with malaria. Enormous efforts are being made to identify suitable drug targets in order to develop newer classes of drug. Helicases play crucial roles in DNA metabolism and have been proposed as therapeutic targets for cancer therapy as well as viral and parasitic infections. Genome wide analysis revealed that Plasmodium falciparum possesses UvrD helicase, which is absent in the human host.. Recently the biochemical characterization of P. falciparum UvrD helicase revealed that N-terminal UvrD (PfUDN) hydrolyses ATP, translocates in 3' to 5' direction and interacts with MLH to modulate each other's activity. In this follow up study, further characterization of P. falciparum UvrD helicase is presented. Here, we screened the effect of various DNA interacting compounds on the ATPase and helicase activity of PfUDN. This study resulted into the identification of daunorubicin (daunomycin), netropsin, nogalamycin, and ethidium bromide as the potential inhibitor molecules for the biochemical activities of PfUDN with IC50 values ranging from ~3.0 to ~5.0 μM. Interestingly etoposide did not inhibit the ATPase activity but considerable inhibition of unwinding activity was observed at 20 μM. Further study for analyzing the importance of PfUvrD enzyme in parasite growth revealed that PfUvrD is crucial/important for its growth ex-vivo.. As PfUvrD is absent in human hence on the basis of this study we propose PfUvrD as suitable drug target to control malaria. Some of the PfUvrD inhibitors identified in the present study can be utilized to further design novel and specific inhibitor molecules.

Topics: Antigens, Protozoan; Cells, Cultured; Daunorubicin; DNA Helicases; DNA, Protozoan; Ethidium; Etoposide; Humans; Malaria, Falciparum; Molecular Targeted Therapy; Netropsin; Nogalamycin; Plasmodium falciparum; RNA, Double-Stranded; RNA, Protozoan