Cytotoxic evaluation and chemical investigation of tomatoes from plants (Solanum lycopersicum L.) grown in uncontaminated and experimentally contaminated soils

Abstract

The aim of this study was to evaluate the cytotoxic activity and the chemical composition of the tomato extracts coming from, Pomodoro Giallo and San Marzano Cirio 3, and then to evaluate the potential changes when plants were grown in soils contaminated by cadmium, chromium and lead. Extracts were investigated by UHPLC-HRMS and UV-Vis. Cell viability (CellTiter-Glo Luminescent assay), enzyme aldehyde dehydrogenase activity (ALDEFLOUR Assay), cell cycle progression (Accuri C6 Flow Cytometer), apoptosis and necrosis (Annexin V-FITC assay) were evaluated on two gastric cancer (AGS and NCI-N87) and two colorectal cancer (HT-29 and HCT 116) cell lines. Different content of polyphenol and carotenoid constituents was observed. Extracts from uncontaminated soil induced cytotoxic activity towards all selected cancer cells, while extracts coming from contaminated soils showed the aberrant phenotype increased in colorectal cancer cells. Chloroform extracts exerted the highest cytotoxic activity. AGS and HT-29 were the most sensitive to cell cycle arrest and to apoptosis. No necrotic effect was observed in HCT 116. The contrasting effects on cancer cells were observed based on tomato variety, the extract polarity, heavy metal identity, and tested cell line. The investigation of potential adverse health effects due to Cd in the fruits should be explored.

Figure 1

UV–Vis spectra of lipophilic extracts. UV–Vis spectra of lipophilic extracts of PG (A) and PR (B) samples (CTR = plants grown in uncontaminated soils; Cd, Cr, Pb = plants grown in soils experimentally contaminated by cadmium, chromium and lead). The software used to generate this figure was PeakView—Analyst TF 1.7.

Figure 2

ALDH positive-cell population in AGS, NCI-N87, HT-29 and HCT 116 cells after 72-h. ALDH positive-cell population in AGS, NCI-N87, HT-29 and HCT 116 cells after 72-h treatment with IC50 of chloroform and methanol extracts of Pomodoro Giallo (PG) and San Marzano Cirio 3 (PR) fruits, grown with or without heavy metals (Cd, Cr, Pb) contamination. Results are expressed as means ± standard deviation of three independent experiments. Significant differences from the negative control (NC, untreated cells) are highlighted by letters (a: p < 0.05; b: p < 0.01; c: p < 0.0001—Dunnett’s test). Significant differences between uncontaminated and contaminated tomato extracts are highlighted by asterisks (*p < 0.05; **p < 0.01; ***p < 0.0001—Dunnett’s test). The software used to generate this figure was GraphPad Prism 5.

Figure 3

Histograms of AGS, NCI-N87, HT-29 and HCT 116 cell population distribution (in percent) in different cell cycle (G0/G1–S–G2/M) phases after 72-h treatment. Histograms of AGS, NCI-N87, HT-29 and HCT 116 cell population distribution (in percent) in different cell cycle (G0/G1–S–G2/M) phases after 72-h treatment with IC50 of cloroform and methanol extracts of Pomodoro Giallo (PG) and San Marzano Cirio 3 (PR) fruits, grown with or without heavy metals (Cd, Cr, Pb) contamination. Results are expressed as means ± SD of three separate experiments. Significant differences from the negative control (NC, untreated cells) are highlighted by letters (a: p < 0.05; b: p < 0.01; c: p < 0.0001—Dunnett’s test). Significant differences between uncontaminated and contaminated tomato extracts are highlighted by asterisks (*p < 0.05; **p < 0.01; ***p < 0.0001—Dunnett’s test). The software used to generate this figure was GraphPad Prism 5.

Figure 4

Histograms of apoptotic and necrotic AGS, NCI-N87, HT-29 and HCT 116 cell distribution (in percent) after 72-h treatment. Histograms of apoptotic and necrotic AGS, NCI-N87, HT-29 and HCT 116 cell distribution (in percent) after 72-h treatment with IC50 of chloroform and methanol extracts of Pomodoro Giallo (PG) and San Marzano Cirio 3 (PR) fruits, grown with or without heavy metals (Cd, Cr, Pb) contamination. Results are expressed as means ± SD of three separate experiments. Significant differences from the negative control (NC, untreated cells) are highlighted by letters (a: p < 0.05; b: p < 0.01; c: p < 0.0001—Dunnett’s test). Significant differences between uncontaminated and contaminated tomato extracts are highlighted by asterisks (*p < 0.05; **p < 0.01; ***p < 0.0001—Dunnett’s test). The software used to generate this figure was GraphPad Prism 5.