title: Green Synthesis of Silver and Titanium Dioxide Nanoparticles Using Euphorbia prostrata Extract Shows Shift from Apoptosis to G0/G1 Arrest followed by Necrotic Cell Death in Leishmania donovani.
abstract: The aim of the present study was to synthesize silver (Ag) and titanium dioxide (TiO2) nanoparticles (NPs) using green synthesis from aqueous leaf extract of Euphorbia prostrata as antileishmanial agents and to explore the underlying molecular mechanism of induced cell death. In vitro antileishmanial activity of synthesized NPs was tested against promastigotes of Leishmania donovani by alamarBlue and propidium iodide uptake assays. Antileishmanial activity of synthesized NPs on intracellular amastigotes was assessed by Giemsa staining. The leishmanicidal effect of synthesized Ag NPs was further confirmed by DNA fragmentation assay and by cell cycle progression and transmission electron microscopy (TEM) of the treated parasites. TEM analysis of the synthesized Ag NPs showed a spherical shape with an average size of 12.82 ± 2.50 nm, and in comparison to synthesized TiO2 NPs, synthesized Ag NPs were found to be most active against Leishmania parasites after 24 h exposure, with 50% inhibitory concentrations (IC50) of 14.94 μg/ml and 3.89 μg/ml in promastigotes and intracellular amastigotes, respectively. A significant increase in G0/G1 phase of the cell cycle with a subsequent decrease in S (synthesis) and G2/M phases compared to controls was observed. The growth-inhibitory effect of synthesized Ag NPs was attributed to increased length of S phase. A decreased reactive oxygen species level was also observed, which could be responsible for the caspase-independent shift from apoptosis (G0/G1 arrest) to massive necrosis. High-molecular-weight DNA fragmentation as a positive consequence of necrotic cell death was also visualized. We also report that the unique trypanothione/trypanothione reductase (TR) system of Leishmania cells was significantly inhibited by synthesized Ag NPs. The green-synthesized Ag NPs may provide promising leads for the development of cost-effective and safer alternative treatment against visceral leishmaniasis.
authors.affiliation: Unit of Nanotechnology and Bioactive Natural Products, Post Graduate and Research Department of Zoology, C. Abdul Hakeem College, Melvisharam, Vellore District, Tamil Nadu, India.
authors.forename: Abdul Abduz
authors.initials: AA
authors.lastname: Zahir
authors.affiliation: Biochemistry Division, CSIR Central Drug Research Institute, Jankipuram Extension, Lucknow, India.
authors.forename: Indira Singh
authors.initials: IS
authors.lastname: Chauhan
authors.affiliation: Unit of Nanotechnology and Bioactive Natural Products, Post Graduate and Research Department of Zoology, C. Abdul Hakeem College, Melvisharam, Vellore District, Tamil Nadu, India.
authors.forename: Asokan
authors.initials: A
authors.lastname: Bagavan
authors.affiliation: Unit of Nanotechnology and Bioactive Natural Products, Post Graduate and Research Department of Zoology, C. Abdul Hakeem College, Melvisharam, Vellore District, Tamil Nadu, India.
authors.forename: Chinnaperumal
authors.initials: C
authors.lastname: Kamaraj
authors.affiliation: Unit of Nanotechnology and Bioactive Natural Products, Post Graduate and Research Department of Zoology, C. Abdul Hakeem College, Melvisharam, Vellore District, Tamil Nadu, India.
authors.forename: Gandhi
authors.initials: G
authors.lastname: Elango
authors.affiliation: Transmission Electron Microscopy, CSIR Indian Institute of Toxicology Research, Lucknow, India.
authors.forename: Jai
authors.initials: J
authors.lastname: Shankar
authors.affiliation: Transmission Electron Microscopy, CSIR Indian Institute of Toxicology Research, Lucknow, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Arjaria
authors.affiliation: Organic & Medicinal Chemistry Research Laboratory, Organic Chemistry Division, School of Advanced Sciences, VIT University, Vellore, Tamil Nadu, India.
authors.forename: Selvaraj Mohana
authors.initials: SM
authors.lastname: Roopan
authors.affiliation: Unit of Nanotechnology and Bioactive Natural Products, Post Graduate and Research Department of Zoology, C. Abdul Hakeem College, Melvisharam, Vellore District, Tamil Nadu, India abdulrahuman6@hotmail.com neeloo888@yahoo.com.
authors.forename: Abdul Abdul
authors.initials: AA
authors.lastname: Rahuman
authors.affiliation: Biochemistry Division, CSIR Central Drug Research Institute, Jankipuram Extension, Lucknow, India abdulrahuman6@hotmail.com neeloo888@yahoo.com.
authors.forename: Neeloo
authors.initials: N
authors.lastname: Singh
mesh_terms: D000981:Antiprotozoal Agents / Q000737:chemistry / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D028481:Euphorbia / Q000737:chemistry*; D016193:G1 Phase / Q000187:drug effects; D007893:Leishmania donovani / Q000187:drug effects*; D007898:Leishmaniasis, Visceral / Q000188:drug therapy / Q000378:metabolism; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D009336:Necrosis / Q000188:drug therapy; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D012834:Silver / Q000737:chemistry / Q000494:pharmacology*; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000981:Antiprotozoal Agents; D010936:Plant Extracts; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D020169:Caspases