Background:
Cigarette smoke is harmful to human health at both cellular and genetic levels. Recently, a unique bioassay for smoke cytotoxicity using air pollution-sensitive plant cells (tobacco) has been proposed.

Methods:
Model plant cells (tobacco Bel-W3 cells) and human cells (alveolar epithelial A549 cells) suspended in fresh culture media were exposed to cigarette smoke sampled after lighting the tip of cigarettes (with vs. without menthol capsules) which were attached to a glass pipe connected to the cell-containing plastic tubes. Control cultures were also assessed.

Results:
After exposing tobacco plant cells to cigarette smoke, cell death occurred in a dose-dependent manner. Cell death was significantly enhanced by mentholated smoke, while menthol alone was shown to be inert suggesting that menthol synergistically contributes to the enhancement of cell death, initiated by smoke-associated compounds. The enhanced toxicity of mentholated smoke was confirmed in human alveolar epithelial A549 cells.

Conclusions:
Cigarette smoke cytotoxicity leading to cell death assessed in plant and human model cells was enhanced by menthol. Further research into these findings is encouraged.