Racemoside A, an anti-leishmanial, water-soluble, natural steroidal saponin, induces programmed cell death in Leishmania donovani.
Leishmaniasis remains a major health problem of the tropical and subtropical world. The visceral form causes the most fatalities if left untreated. Dramatic increases in the rates of infection and drug resistance and the non-availability of safe vaccines have highlighted the need for identification of novel and inexpensive anti-leishmanial agents. This study reports that racemoside A, a water-soluble steroidal saponin purified from the fruits of Asparagus racemosus, is a potent anti-leishmanial molecule effective against antimonial-sensitive (strain AG83) and -unresponsive (strain GE1F8R) Leishmania donovani promastigotes, with IC(50) values of 1.15 and 1.31 microg ml(-1), respectively. Incubation of promastigotes with racemoside A caused morphological alterations including cell shrinkage, an aflagellated ovoid shape and chromatin condensation. This compound exerts its leishmanicidal effect through the induction of programmed cell death mediated by the loss of plasma membrane integrity as detected by binding of annexin V and propidium iodide, loss of mitochondrial membrane potential culminating in cell-cycle arrest at the sub-G(0)/G(1) phase, and DNA nicking shown by deoxynucleotidyltransferase-mediated dUTP end labelling (TUNEL). Racemoside A also showed significant activity against intracellular amastigotes of AG83 and GE1F8R at a 7-8-fold lower dose, with IC(50) values of 0.17 and 0.16 microg ml(-1), respectively, and was non-toxic to murine peritoneal macrophages up to a concentration of 10 microg ml(-1). Hence, racemoside A is a potent anti-leishmanial agent that merits further pharmacological investigation.
Dutta
Avijit
A
Department of Infectious Disease and Immunology, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
Ghoshal
Angana
A
Department of Infectious Disease and Immunology, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
Mandal
Debayan
D
Steroid and Terpenoid Chemistry, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
Mondal
Nirup B
NB
Steroid and Terpenoid Chemistry, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
Banerjee
Sukdeb
S
Steroid and Terpenoid Chemistry, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
Sahu
Niranjan P
NP
Steroid and Terpenoid Chemistry, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
Mandal
Chitra
C
Department of Infectious Disease and Immunology, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D000981:Antiprotozoal Agents / Q000494:pharmacology* / Q000633:toxicity; D017209:Apoptosis; D027761:Asparagus Plant / Q000737:chemistry; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival; D002478:Cells, Cultured; D053904:DNA Breaks, Single-Stranded; D020287:In Situ Nick-End Labeling; D020128:Inhibitory Concentration 50; D007893:Leishmania donovani / Q000166:cytology / Q000187:drug effects*; D017737:Macrophages, Peritoneal / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D010936:Plant Extracts / Q000494:pharmacology; D011419:Propidium / Q000378:metabolism; D012503:Saponins / Q000302:isolation & purification / Q000494:pharmacology*; D013256:Steroids / Q000302:isolation & purification / Q000494:pharmacology*
D017304:Annexin A5; D000981:Antiprotozoal Agents; D010936:Plant Extracts; D012503:Saponins; D013256:Steroids; D011419:Propidium