Title: Exposure to selected limonene oxidation products: 4-oxopentanal (4-OPA), 3-isopropenyl-6-oxo-heptanal (IPOH), 4-acetyl-1-methylcyclohexene (4-AMCH) induce oxidative stress and inflammation in human lung epithelial cell lines
Citation: CHEMOSPHERE vol. 191 p. 937-945
Publication Year: 2018
JRC N°: JRC106911
ISSN: 0045-6535
URI: http://www.sciencedirect.com/science/article/pii/S0045653517316466?via%3Dihub
DOI: 10.1016/j.chemosphere.2017.10.065
Type: Articles in periodicals and books
Abstract: Limonene oxidation products (LOPs) have gained interest owing to multiple reports on harmful health effects. Recently, it has been shown that the selected LOPs: 4-OPA, IPOH and 4-AMCH have sensory irritation effects in mice and increased inflammatory markers in human lung cells. The present study was therefore undertaken to investigate the potential capacity of 4-OPA, IPOH and 4-AMCH to cause cell membrane damage (by lactate dehydrogenase assay), oxidative stress (by fluorescence assay and liquid chromatography) and inflammation (by enzyme-linked immunosorbent assay) in human alveolar (A549) and bronchial (16HBE14o-) epithelial cell lines. The overall results suggest that 4-OPA, IPOH have cytotoxic effects on human pulmonary cells, and that this might be mediated by ROS: the highest concentration applied of IPOH [500 µM] enhanced ROS generation by 100-fold (A549) and a 230-fold change (16HBE14o-) compared to the baseline. 4-OPA [500 µM] increased ROS levels by 1.4-fold ± 0.3 (A549) and by 127-fold ± 10.5 (16HBE14o-), while treatment with 4-AMCH [500 µM] led to a 0.9-fold ± 0.2 (A549) and 49-fold ± 12.8 (16HBE14o-) increase. IPOH [500 µM] caused a decrease in the thiol-state balance (e.g. 2 h post-treatment, GSH : GSSG ratio was significantly reduced by 37% compared with the untreated 16HBE14o- cells). 4-OPA [500 µM] decreased the GSH:GSSG ratio by a 1.3-fold change in A549 cells and a 1.4-fold change in 16HBE14o- cells. No statistically significant decrease in the GSH:GSSG ratio in both A549 and 16HBE14o- cell lines was observed at 500 µM 4-AMCH. In addition, both IPOH and 4-OPA [31.2 µM] increased the amount of the inflammatory markers: RANTES, VEGF and EGF (e.g. 2.0-fold change of RANTES amount determined in 16HBE14o- cells treated with IPOH [31.2 µM]). On the other hand, neither cell lines treated with 4-AMCH [31.2 µM] released statistically significant amounts of the selected inflammatory markers.
JRC Directorate:Health, Consumers and Reference Materials

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