An orally effective dihydropyrimidone (DHPM) analogue induces apoptosis-like cell death in clinical isolates of Leishmania donovani overexpressing pteridine reductase 1.
The protozoan parasite Leishmania donovani is the causative agent of visceral leishmaniasis. The enzyme pteridine reductase 1 (PTR1) of L. donovani acts as a metabolic bypass for drugs targeting dihydrofolate reductase (DHFR); therefore, for successful antifolate chemotherapy to be developed against Leishmania, it must target both enzyme activities. Leishmania cells overexpressing PTR1 tagged at the N-terminal with green fluorescent protein were established to screen for proprietary dihydropyrimidone (DHPM) derivatives of DHFR specificity synthesised in our laboratory. A cell-permeable molecule with impressive antileishmanial in vitro and in vivo oral activity was identified. Structure activity relationship based on homology model drawn on our recombinant enzyme established the highly selective inhibition of the enzyme by this analogue. It was seen that the leishmanicidal effect of this analogue is triggered by programmed cell death mediated by the loss of plasma membrane integrity as detected by binding of annexin V and propidium iodide (PI), loss of mitochondrial membrane potential culminating in cell cycle arrest at the sub-G0/G1 phase and oligonucleosomal DNA fragmentation. Hence, this DHPM analogue [(4-fluoro-phenyl)-6-methyl-2-thioxo-1, 2, 3, 4-tetrahydropyrimidine-5-carboxylic acid ethyl ester] is a potent antileishmanial agent that merits further pharmacological investigation.
Singh
Neeloo
N
Drug Target Discovery & Development Division, Central Drug Research Institute, Lucknow 226001, India. neeloo888@yahoo.com
Kaur
Jaspreet
J
Kumar
Pranav
P
Gupta
Swati
S
Singh
Nasib
N
Ghosal
Angana
A
Dutta
Avijit
A
Kumar
Ashutosh
A
Tripathi
Ramapati
R
Siddiqi
Mohammad Imran
MI
Mandal
Chitra
C
Dube
Anuradha
A
D000818:Animals; D017304:Annexin A5 / Q000494:pharmacology; D000981:Antiprotozoal Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis; D016923:Cell Death; D002470:Cell Survival; D006224:Cricetinae; D053938:DNA Fragmentation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical / Q000379:methods; D007202:Indicators and Reagents / Q000494:pharmacology; D007893:Leishmania donovani / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D007898:Leishmaniasis, Visceral / Q000469:parasitology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D010088:Oxidoreductases / Q000096:biosynthesis*; D011419:Propidium / Q000494:pharmacology; D011744:Pyrimidinones / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
D017304:Annexin A5; D000981:Antiprotozoal Agents; D007202:Indicators and Reagents; D011744:Pyrimidinones; D011419:Propidium; D010088:Oxidoreductases; C085592:pteridine reductase