In planta assimilation and characterization of metal nanoparticles in in vitro shoots of Withania somnifera and its therapeutic evaluation using Rotenone induced SH-SY5Y cells
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Date
2024-08
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Avinashilingam
Abstract
Withania somnifera is a predominant medicinal herb having
economically valuable secondary metabolites and high reduction potential.
Apart from being medicinal, W. somnifera also has hyper accumulation
capability especially with heavy metals. Initially, metal bioaccumulation and
metal reduction capability of field grown shoot tissues of W. somnifera was
analysed using elemental analysis and extract based green synthesis of silver
nanoparticles. The capability of W. somnifera to grow under the influence of
heavy metal stress and accumulation of secondary metabolites is studied using
in vitro shoot cultures. On confirmation of metal reduction capability, 45-days
old in vitro shoot cultures were treated with different concentrations of silver
nitrate and lead acetate salts at acute and chronic conditions. An Increase in
biomass, primary and secondary metabolites (withanolides) was found to be
accumulated in considerable amounts in metal salts treated in vitro shoots
compared to in vitro control. Among the metal treated shoots, 1mM AgNO3
treatment for 12 days period and 0.8mM PbAc treatment for 12 days period
was selected as the optimum treatment conditions and selected for the further
studies. Optimum AgNO3 and PbAc treated shoots along with control shoots
were analysed for its respective metal content using ICP MS analysis. The
concentration of Ag in optimum AgNO3 treated shoot is 50.8ppm and Pb in
optimum PbAc treated shoot is 405ppm. The nature of Ag and Pb within the
shoot was analysed by TEM with EDAX analysis. The presence of Ag and Pb
nanoparticles in spherical and rod shape was confirmed. In addition, the
neuroprotective activity of metal treated IVS along with field grown tissues of
W. somnifera was studied using Parkinson’s disease cell model (SH-SY5Y
cells). Compared to field grown tissues, AgNO3 treated IVS exhibited increased
neuroprotective activity against rotenone toxicity. Molecular docking study was
conducted to analyse the binding site of rotenone and selected withanolides in
mitochondrial complex I protein. Multiple ligand simultaneous docking revealed
a binding of rotenone with withaferin A leaves complex I protein uninhibited.
Thus, from the current study, we conclude that AgNO3 treated IVS along with
increased withaferin A content has higher neuroprotective activity which may
be used as a potential drug for toxins induced PD.
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Biochemistry