Search

Alkylphenols are byproducts of anthropogenic activities that widely contaminate waters, soils and air; among them, the most represented are 4-nonylphenol (4-NP) and 4-octylphenol (4-OP). These compounds tend to bioaccumulate in animal and plant tissues and also represent a risk to human health. Indeed, humans are constantly exposed to alkylphenols through ingestion of contaminated water and food, inhalation and dermal absorption. In the present work, we characterized the cytotoxic ability of 4-OP towards several human cell lines, representing the potential main targets in the human body, also comparing its effect with that of 4-NP and of a mixture of both 4-OP and 4-NP in a range of concentrations between 1 and 100 μM. Viability assays demonstrated that each cell type had a peculiar sensitivity to 4-OP and that, in some cases, a combination of the two alkylphenols displayed a higher cytotoxic activity with respect to the single compound. Then, we focused our attention on a liver cell line (HepG2) in which we observed that 4-OP increased cell death and also caused interference with protective physiological cell processes, such as the unfolded protein response, autophagy and the antioxidant response. Finally, our experimental data were compared and correlated with ADMET properties originating from an in silico analysis. Altogether, our findings highlight a possible contribution of this pollutant to deregulation of the normal homeostasis in human liver cells.

Pergularia tomentosa L., a milkweed tropical plant belonging to the family Asclepiadaceae, is a rich source of unusual cardiac glycosides, characterised by transfused A/B rings and a sugar moiety linked by a double link, generating a dioxanoid structure. In the present report, five cardenolides isolated from the aerial parts of the plant (calactin, calotropin, 12β-hydroxycalactin, 12β,6′-dihydroxycalotropin, and 16α-hydroxycalotropin) were investigated for their biological effects on a human hepatocarcinoma cell line. Cell viability was monitored by an MTT assay. The occurrence of apoptosis was evaluated by detecting caspase-3 activation and chromatin fragmentation. The ability of these compounds to induce autophagy was analysed by monitoring two markers of the autophagic process, LC3 and p62. Our results indicated that all cardenolides had cytotoxic effects, with IC50 ranging from 0.127 to 6.285 μM. All compounds were able to induce apoptosis and autophagy, calactin being the most active one. Some of them also caused a reduction in cell migration and a partial block of the cell cycle into the S-phase. The present study suggests that selected cardenolides from aerial parts of P. tomentosa, particularly calactin, possess potentially desirable properties for further investigation as anticancer agents. [ABSTRACT FROM AUTHOR]