| Summary: | Traditional methods of nanoparticles synthesis frequently use toxics
chemicals and substantial energy, which may have detrimental effects on the
environment and human health. Recently, plant-based synthesis of nanoparticles
(AgNPs) has emerged as a promising green synthesis method. Herein, we reported
the green synthesis of AgNPs using the aqueous extract of A. angustiloba leaves and
assessed its antiproliferative mechanisms. Initially, the physiochemical properties of
A. angustiloba-AgNPs were characterised using UV–Vis spectrophotometry, FT-IR,
FESEM, EDX, TEM, XRD and zeta sizer analyses. The cytotoxicity of A.
angustiloba-AgNPs was examined by MTT assays against the A431 cancer cell line.
The morphology of the treated cells was examined using fluorescence microscopy
and the antiproliferative mechanisms of the nanoparticles in A431 cells were
investigated by annexin-FITC/propidium iodide (PI) staining and DNA cell cycle
analysis using flow cytometry. The intracellular ROS levels were measured using a
commercially available kit. The expression of apoptosis and cell cycle-related
proteins was determined by Western blotting. The results of SEM and TEM revealed
that the nanoparticles showed a spherical shape with the highest particle size
distribution was 11 to 14 nm, while a mean hydrodynamic size of 61.21 ±3.96 nm
and a zeta potential value of –18.67 ±3.12 mV that was measured by DLS. Besides
that, the XRD pattern showed that metallic Ag has a face-centred cubic structure
with the diffraction peak values at 2θ of 38.11°, 44.26°, 64.29°, and 77.07° corresponding to lattice planes at (111), (200), (220), and (311), respectively. FTIR
results revealed the presence of –OH, C=C and C-O may serve as a capping and
stabilising agent. The nanoparticles inhibited the growth of A431 cells with an IC50
value of 39.58 μg/mL after 72 h of treatment. Meanwhile, the IC50 values for extract
alone and commercial AgNPs were 164.3 ug/ml and 16.89 ug/ml, respectively.
Further investigation has shown that the nanoparticles induced both apoptosis and
cell cycle arrest at S-phase in A431 cancer cells. Western blotting analysis revealed
that A. angustiloba-AgNPs decreased the expression of Bcl-2 while increasing the
expression of cleaved caspase-3, 9 and Bax. Moreover, the downregulation of cyclin
E protein indicated impaired progression in the S phase of the cell cycle. In
summary, A. angustiloba-AgNPs inhibit cell proliferation and promote apoptosis in
A431 cancer cells through increasing intracellular ROS production and activating the
caspase-dependent apoptotic pathway and cell cycle arresting. These preliminary
findings provided an insight that A. angustiloba-AgNPs have high anti-neoplastic
potential, therefore further pharmacological studies should be conducted to unveil its
attractiveness as an anticancer agent.
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