Cytotoxicity and insulin resistance reversal ability of biofunctional phytosynthesized MgO nanoparticles

Abstract

The present study investigates the cytotoxicity of hexagonal MgO nanoparticles synthesized via Amaranthus tricolor leaf extract and spherical MgO nanoparticles synthesized via Amaranthus blitum and Andrographis paniculata leaf extracts. In vitro cytotoxicity analysis showed that the hexagonal MgO nanoparticles synthesized from A. tricolor extract demonstrated the least toxicity to both diabetic and non-diabetic cells at 600 μl/ml dosage. The viability of the diabetic cells (3T3-L1) after incubation with varying dosages of MgO nanoparticles was observed to be 55.3%. The viability of normal VERO cells was 86.6% and this stabilized to about 75% even after exposure to MgO nanoparticles dosage of up to 1000 μl/ml. Colorimetric glucose assay revealed that the A. tricolor extract synthesized MgO nanoparticles resulted in ~ 28% insulin resistance reversal. A reduction in the expression of GLUT4 protein at 54 KDa after MgO nanopaSrticles incubation with diabetic cells was observed via western blot analysis to confirm insulin reversal ability. Fluorescence microscopic analysis with propidium iodide and acridine orange dyes showed the release of reactive oxygen species as a possible mechanism of the cytotoxic effect of MgO nanoparticles. It was inferred that the synergistic effect of the phytochemicals and MgO nanoparticles played a significant role in delivering enhanced insulin resistance reversal capability in adipose cells.

Keywords: Adipose cells; Diabetes; Insulin resistance; MgO nanoparticles; Phytosynthesis.

Fig. 1

Calibration curve to determine MgO nanoparticle concentration. Different concentrations (0.4–2 mg/ml) of MgO nanopowders were dissolved double distilled water and obtained an OD value at 322 nm wavelength and its subsequent linear fit equation for the determination of phytosynthesized MgO nanoparticle concentration

Fig. 2

TEM micrograph of MgO nanoparticles phytosynthesized using a A. tricolor (sample A) (Jeevanandam et al. 2019a); b A. blitum (sample B) and c A. paniculata (sample C). Reproduced with the permission from (Jeevanandam et al. 2017c), © The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS)

Fig. 3

The viability of adipose cells after treatment with samples A, B and C of MgO nanoparticles at varying dosages showing dose dependent toxicity of nanoparticles with IC₅₀ at 600 μl/ml

Fig. 4

Micrograph of 3T3-L1 cells after treatment with phytosynthesized MgO nanoparticles samples A, B and C, which reveals the alterations in the morphology of 3T3-L1 fibroblast cells due to the presence of nanoparticles

Fig. 5

Comparative cell viability analysis after treating diabetic (3T3-L1) and non-diabetic (VERO) cell lines with varying dosages of sample A, showing that the hexagonal MgO nanoparticles are less toxic towards non-diabetic cells

Fig. 6

Time-dependent glucose reduction profiles for control cells and phytosynthesized MgO nanoparticles treated cells at a dosage of 600 μl/ml

Fig. 7

Estimation of GLUT4 protein expression in a control and b Sample A, showing the reduced expression of GLUT4 protein in sample A incubated cells, compared to control indicating the insulin resistance reversal ability of MgO nanoparticles

Fig. 8

Fluorescence microscopic images of propidium iodide stained 3T3-L1 cells after 24 h a control cells, b cell treated with 600 μl/ml of MgO nanoparticles and acridine orange stained 3T3-L1 cells after 24 h c control cells and d cells treated with 600 μl/ml of MgO nanoparticles

Fig. 9

Schematics of the proposed mechanism of reversing insulin resistance in adipose cells. The stages of insulin resistance reversal by MgO nanoparticles may include: 1. diabetic adipose cells incubated with MgO nanoparticles, 2. nanoparticle binds to the cells, 3. dissociation of ions from nanoparticles, 4. internalization of magnesium ions into cells, 5. activation of intracellular enzymes, 6. reverses insulin resistance, 7. entry of insulin into the cells, 8. cytoplasmic expression of GLUT4 protein in plasma membrane, 9. GLUT4 allows glucose uptake into cells, 10. glucose reduction by insulin and 11. ATP formation in cells