Pterostilbene Nanoparticles Downregulate Hypoxia-Inducible Factors in Hepatoma Cells Under Hypoxic Conditions

Figures & data

Table 1 Water Solubility, Yield, Encapsulation Efficiency, Particle Size, and PI of PTS and Its Nanoparticle Formulation

PTS:EE:PVA	Water Solubility (μg/mL)	Yield (%)	Encapsulation Efficiency (%)	Particle Size (nm)	PI
1:2:2	158.29 ± 5.65	29.34 ± 5.68	>99	123.53 ± 3.73*	0.22 ± 0.020*
1:4:4	482.49 ± 11.35	79.09 ± 4.63	>99	94.67 ± 0.81*	0.13 ± 0.010*
1:8:8	604.38 ± 49.37	86.33 ± 4.64	>99	102.77 ± 0.49*	0.14 ± 0.004*
PTS	<0.05	ND	ND	2816.53 ± 79.42	1.08 ± 0.020

Notes: Values are mean ± SD (n = 3). *P < 0.05: statistically significant difference compared with PTS.

Abbreviations: PTS, pterostilbene; PSN, PTS nanoparticles; PI, polydispersity index; SD, standard deviation; ND, not detected.

Figure 1 Transmission electron microscopy (TEM) image of PSN (A), scanning electron microscopy (SEM) images of raw PTS (B) and PSN (C).

Figure 2 In vitro drug release profiles of raw PTS and PSN in two phosphate buffer solutions.

Figure 3 Crystalline and amorphous transformation using powder XRD analysis. The ratio represents the content of PTS:EE:PVA in PSN and the Blank represents only EE and PVA.

Figure 4 Analysis of hydrogen bonding interactions. FT-IR (A) and ¹H NMR (B–F); (B) nanoparticle carrier, (C) PTS, (D) PSN1:2:2, (E) PSN1:4:4, (F) PSN1:8:8. The direction of the arrows represents the position of the hydrogen bond between PTS and EE-PVA.

Table 2 400 MHz ¹H Chemical Shift (δ, ppm) of PTS Protons in Raw State and Chemical Shift Displacements (Δδ, ppm) of PTS Prepared by EE and PVA

Proton Position	δPTS	With Nanocarrier
		δPSN	Δδ
Ha	6.364	6.357	−0.007
Hb	6.712	6.701	−0.011
Hc	7.131	7.121	−0.010
Hd	6.914	6.905	−0.009
He	7.422	7.392	−0.030
Hf	6.770	6.750	−0.020
Methyl	3.761	3.758	−0.003
Hydroxyl	9.617	ND	ND

Abbreviations: ND, not detected; Δδ, δ_PSN -δ_PTS.

Figure 5 Chemical structure of pterostilbene.

Figure 6 Expression of HIF-1α protein at different time points after hypoxia, and viability of HepG2 cells treated with PTS and PSN for 24 h. Viability of HepG2 cells and expression of HIF-1α protein (A). Cell viability following treatment with PTS (B) and PSN (C) under all hypoxia conditions. n = 3 of each group; *P < 0.05 compared with control.

Figure 7 Expression of hypoxia-induced and antiapoptotic proteins post-hypoxia (A) and pre-hypoxia (B). Protein was collected after treatment of HepG2 cells with 40 μM PTS or PSN containing 4 μM PTS. Protein expression was determined by Western blotting. Columns represent mean ± standard deviation (n = 3). P < 0.05: ^aNormoxia compared with control; ^$PTS compared with control; ^#PSN compared with control; *PTS compared with PSN.