Clotrimazole inhibits hemoperoxidase of Plasmodium falciparum and induces oxidative stress. Proposed antimalarial mechanism of clotrimazole.
The mechanism of antimalarial activity of clotrimazole was studied placing emphasis on its role in inhibiting hemoperoxidase for inducing oxidative stress in Plasmodium falciparum. Clotrimazole, in the presence of H2O2, causes irreversible inactivation of the enzyme, and the inactivation follows pseudo-first order kinetics, consistent with a mechanism-based (suicide) mode. The pseudo-first order kinetic constants are ki = 2.85 microM, k(inact) = 0.9 min(-1), and t(1/2) = 0.77 min. The one-electron oxidation product of clotrimazole has been identified by EPR spectroscopy as the 5,5'-dimethyl-1-pyrroline N-oxide (DMPO) adduct of the nitrogen-centered radical (aN = 15 G), and as DMPO protects against inactivation, this radical is involved in the inactivation process. Binding studies indicate that the clotrimazole oxidation product interacts at the heme moiety, and the heme-clotrimazole adduct has been dissociated from the inactivated enzyme and identified (m/z 1363) by mass analysis. We found that the inhibition of hemoperoxidase increases the accumulation of H2O2 in P. falciparum and causes oxidative stress. Furthermore, the inhibition of hemoperoxidase correlates well with the inhibition of parasite growth. The results described herein indicate that the antimalarial activity of clotrimazole might be due to the inhibition of hemoperoxidase and subsequent development of oxidative stress in P. falciparum.
Trivedi
Vishal
V
Molecular and Structural Biology Division, Central Drug Research Institute, Chatter Manzil Palace, Mahatma Gandhi Marg, Lucknow 226001, Uttar Pradesh, India.
Chand
Prem
P
Srivastava
Kumkum
K
Puri
Sunil K
SK
Maulik
Prakas R
PR
Bandyopadhyay
Uday
U
D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry; D000962:Antimalarials / Q000494:pharmacology*; D002384:Catalysis; D003022:Clotrimazole / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005609:Free Radicals; D005978:Glutathione / Q000737:chemistry; D006131:Growth Inhibitors / Q000494:pharmacology*; D006418:Heme / Q000737:chemistry / Q000378:metabolism*; D006420:Hemeproteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007700:Kinetics; D015227:Lipid Peroxidation; D013058:Mass Spectrometry; D008956:Models, Chemical; D009584:Nitrogen / Q000737:chemistry; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry; D010544:Peroxidases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D010963:Plasmodium falciparum / Q000201:enzymology*; D011485:Protein Binding; D017382:Reactive Oxygen Species; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013997:Time Factors
D000953:Antigens, Protozoan; D000962:Antimalarials; D004791:Enzyme Inhibitors; D005609:Free Radicals; D006131:Growth Inhibitors; D006420:Hemeproteins; D017382:Reactive Oxygen Species; D006418:Heme; D006861:Hydrogen Peroxide; D010544:Peroxidases; C507620:hemoperoxidase, Plasmodium falciparum; D003022:Clotrimazole; D005978:Glutathione; D009584:Nitrogen; D010100:Oxygen