title: A Novel Spirooxindole Derivative Inhibits the Growth of Leishmania donovani Parasites both In Vitro and In Vivo by Targeting Type IB Topoisomerase.
abstract: Visceral leishmaniasis is a fatal parasitic disease, and there is an emergent need for development of effective drugs against this neglected tropical disease. We report here the development of a novel spirooxindole derivative, N-benzyl-2,2'α-3,3',5',6',7',7α,α'-octahydro-2methoxycarbonyl-spiro[indole-3,3'-pyrrolizidine]-2-one (compound 4c), which inhibits Leishmania donovani topoisomerase IB (LdTopIB) and kills the wild type as well as drug-resistant parasite strains. This compound inhibits catalytic activity of LdTopIB in a competitive manner. Unlike camptothecin (CPT), the compound does not stabilize the DNA-topoisomerase IB cleavage complex; rather, it hinders drug-DNA-enzyme covalent complex formation. Fluorescence studies show that the stoichiometry of this compound binding to LdTopIB is 2:1 (mole/mole), with a dissociation constant of 6.65 μM. Molecular docking with LdTopIB using the stereoisomers of compound 4c produced two probable hits for the binding site, one in the small subunit and the other in the hinge region of the large subunit of LdTopIB. This spirooxindole is highly cytotoxic to promastigotes of L. donovani and also induces apoptosis-like cell death in the parasite. Treatment with compound 4c causes depolarization of mitochondrial membrane potential, formation of reactive oxygen species inside parasites, and ultimately fragmentation of nuclear DNA. Compound 4c also effectively clears amastigote forms of wild-type and drug-resistant parasites from infected mouse peritoneal macrophages but has less of an effect on host macrophages. Moreover, compound 4c showed strong antileishmanial efficacies in the BALB/c mouse model of leishmaniasis. This compound potentially can be used as a lead for developing excellent antileishmanial agents against emerging drug-resistant strains of the parasite.
authors: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.
authors: Sourav
authors: S
authors: Saha
authors: Laboratory of Catalysis and Chemical Biology, Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.
authors: Chiranjit
authors: C
authors: Acharya
authors: Structural Biology & Bio-Informatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.
authors: Uttam
authors: U
authors: Pal
authors: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.
authors: Somenath Roy
authors: SR
authors: Chowdhury
authors: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.
authors: Kahini
authors: K
authors: Sarkar
authors: Structural Biology & Bio-Informatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India.
authors: Nakul C
authors: NC
authors: Maiti
authors: Laboratory of Catalysis and Chemical Biology, Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India jaisankar@iicb.res.in hkmajumder@iicb.res.in.
authors: Parasuraman
authors: P
authors: Jaisankar
authors: Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India jaisankar@iicb.res.in hkmajumder@iicb.res.in.
authors: Hemanta K
authors: HK
authors: Majumder
mesh_terms: D000818:Animals; D000981:Antiprotozoal Agents / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites; D004264:DNA Topoisomerases, Type I / Q000737:chemistry* / Q000378:metabolism; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004351:Drug Resistance / Q000187:drug effects; D005260:Female; D006801:Humans; D007893:Leishmania donovani / Q000187:drug effects* / Q000254:growth & development; D007898:Leishmaniasis, Visceral / Q000188:drug therapy; D008099:Liver / Q000187:drug effects / Q000469:parasitology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000469:parasitology; D008807:Mice, Inbred BALB C; D062105:Molecular Docking Simulation; D011763:Pyrrolizidine Alkaloids / Q000737:chemistry / Q000494:pharmacology*; D013141:Spiro Compounds / Q000737:chemistry / Q000494:pharmacology*; D013154:Spleen / Q000187:drug effects / Q000469:parasitology; D059004:Topoisomerase I Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000981:Antiprotozoal Agents; C000621308:N-benzyl-2,2'alpha-3,3',5',6',7',7alpha,alpha'-octahydro-2-methoxycarbonylspiro(indole-3,3'-pyrrolizidine)-2-one; D011763:Pyrrolizidine Alkaloids; D013141:Spiro Compounds; D059004:Topoisomerase I Inhibitors; D004264:DNA Topoisomerases, Type I