Lipid Nanoparticles Loading Steroidal Alkaloids of Tomatoes Affect Neuroblastoma Cell Viability in an In Vitro Model

Abstract

Tomato by-products represent a good source of phytochemical compounds with health properties, such as the steroidal glycoalkaloid α-tomatine (α-TM) and its aglycone tomatidine (TD). Both molecules have numerous beneficial properties, such as potential anticancer activity. Unfortunately, their therapeutic application is limited due to stability and bioavailability issues. Therefore, a valid strategy seems to be their encapsulation into Solid Lipid Nanoparticles (SLN). The nanoformulations containing α-TM (α-TM-SLN) and TD (TD-SLN) were prepared by solvent-diffusion technique and subsequently characterized in terms of technological parameters (particle size, polydispersity index, zeta potential, microscopy, and calorimetric studies). To assess the effect of α-TM and TD on the percentage of cellular viability in Olfactory Ensheathing Cells (OECs), a peculiar glial cell type of the olfactory system used as normal cells, and in SH-SY5Y, a neuroblastoma cancer cell line, an MTT test was performed. In addition, the effects of empty, α-TM-SLN, and TD-SLN were tested. Our results show that the treatment of OECs with blank-SLN, free α-TM (0.25 µg/mL), and TD (0.50 µg/mL) did not induce any significant change in the percentage of cell viability when compared with the control. In contrast, in SH-SY5Y-treated cells, a significant decrease in the percentage of cell viability when compared with the control was found. In particular, the effect appeared more evident when SH-SY5Y cells were exposed to α-TM-SLN and TD-SLN. No significant effect in blank-SLN-treated SH-SY5T cells was observed. Therefore, SLN is a promising approach for the delivery of α-TM and TD.

Keywords: cellular viability; lipid nanoparticles; tomatidine; tomatine.

Figure 1

Chemical structure of (A) tomatine and (B) tomatidine.

Figure 2

Calibration curves for the quantification of (A) α-TM and (B) TD in SLNs.

Figure 2

Calibration curves for the quantification of (A) α-TM and (B) TD in SLNs.

Figure 3

(A) Mean particle size; (B) polydispersity index (PDI); and (C) Z-potential of empty, α-TM-SLN, and TD-SLN during storage at room temperature for 180 days.

Figure 4

Scanning electron microscopy images of α-TM-SLN and TD-SLN. The scale bar represents 200 nm.

Figure 5

Transmission electron microscopy images of α-TM-SLN and TD-SLN. The scale bar represents 200 nm.

Figure 6

Calorimetric curves, in heating mode, of empty SLN, α-TM-SLN, and TD-SLN.

Figure 7

α-TM and TD-loaded SLN release samples.

Figure 8

MTT tests were performed on OECs (blue) and SH-SY5Y (orange). (A) Untreated cell (CTR), α-TM at 0.25 µg/mL and 0.50 µg/mL for 24 h. (B) OECs and SH-SY5Y were treated with blank SLN, α-TM 0.25 µg/mL, and α-TM-SLN 0.25 µg/mL for 24 h. * p < 0.05 difference vs. CTR; ** p < 0.001 vs. CTR.

Figure 8

MTT tests were performed on OECs (blue) and SH-SY5Y (orange). (A) Untreated cell (CTR), α-TM at 0.25 µg/mL and 0.50 µg/mL for 24 h. (B) OECs and SH-SY5Y were treated with blank SLN, α-TM 0.25 µg/mL, and α-TM-SLN 0.25 µg/mL for 24 h. * p < 0.05 difference vs. CTR; ** p < 0.001 vs. CTR.

Figure 9

MTT tests were performed on OECs (blue) and SH-SY5Y (orange). (A) Untreated cell (CTR), TD at 0.25 µg/mL and 0.50 µg/mL for 24 h. (B) OECs and SH-SY5Y were treated with blank SLN, TD 0.25 µg/mL, and TD-SLN 0.25 µg/mL for 24 h. * p < 0.05 difference vs. CTR.