Green Synthesis of Silver and Titanium Dioxide Nanoparticles Using Euphorbia prostrata Extract Shows Shift from Apoptosis to G ₀ /G ₁ Arrest followed by Necrotic Cell Death in Leishmania donovani

Abstract

The aim of the present study was to synthesize silver (Ag) and titanium dioxide (TiO 2 ) 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 TiO 2 NPs, synthesized Ag NPs were found to be most active against Leishmania parasites after 24 h exposure, with 50% inhibitory concentrations (IC 50 ) of 14.94 g/ml and 3.89 g/ml in promastigotes and intracellular amastigotes, respectively. A significant increase in G 0 /G 1 phase of the cell cycle with a subsequent decrease in S (synthesis) and G 2 /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 (G 0 /G 1 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 costeffective and safer alternative treatment against visceral leishmaniasis.

Mechanistic investigation of phytochemicals involved in green synthesis of gold nanoparticles using aqueous Elaeis guineensis leaves extract: Role of phenolic compounds and flavonoids

“… reported the strong association of the relative percentage amount of each component in GC/MS with the ratio of their average peak area to the total area. Several other bioactive compounds, such as 2,3‐dihydrobenzofuran and 3,4‐dimethylbenzamide containing N─H functional groups, may also contribute to reducing gold ions and stabilizing AuNPs, as reported in previous studies conducted on the synthesis of nanoparticles . Therefore, these Py–GC/MS findings disclosed the possible involvement of polyphenolic compounds along with benzofurans and amides in bioreduction of Au +3 and stabilization of AuNPs.…”

Green synthesis of silver nanoparticles: biomolecule-nanoparticle organizations targeting antimicrobial activity

“…This biogenic nanoparticles offered parasitic activity against Leishmania donovani with a IC 50 value of 3.89 and 14.94 mg ml À1 in amastigotes and promastigotes stage. 237 Similar study by Ahmad et al reported promising antileishmanial activity (IC 50 value 4.37) of green synthesized spherical AgNPs (3-8 nm) using phytochemicals from Sargentodoxa cuneata. 238 Lopes et al reported that green synthesized AgNPs using tannic acid (TA) officered antileishmanial activity.…”

Asteraceae Artemisia campestris and Artemisia herba-alba Essential Oils Trigger Apoptosis and Cell Cycle Arrest in Leishmania infantum Promastigotes

“…Antioxidant activity of EO may be beneficial for the antileishmanial activity of the plant metabolites. It was reported previously by Zahir et al, 2015 [50], that induced decrease of reactive oxygen species level by Euphorbia plant extract is implicated in the death mechanism of Leishmania parasites and could be responsible for the caspase-independent shift from apoptosis to massive necrosis. Furthermore, studies done previously by our team [51] have shown that increase in reactive oxygen species induced by Leishmania Eukaryotic Initiation Factor (LeIF) in murine macrophages is implicated in the enhancing resistance of macrophages J774 to Leishmania infection.…”