Alpha, beta-unsaturated lactones 2-furanone and 2-pyrone induce cellular DNA damage, formation of topoisomerase I- and II-DNA complexes and cancer cell death

• Numerous naturally occurring compounds contain the lactones 2-furanone and 2-pyrone.
• We report that 2-furanone and 2-pyrone induce cellular DNA damage.
• Both lactones induced the formation of topoisomerase-DNA complexes in cells.
• 2-Furanone and 2-pyrone were cytotoxic in leukemia and lung cancer cells.
• Compounds having these lactones may induce carcinogenic and/or anticancer effects.

The alpha, beta-unsaturated lactones 2-furanone and 2-pyrone are part of the chemical structure of a variety of naturally occurring compounds (e.g., cardenolides, bufadienolides, acetogenins, coumarins, and food-flavoring furanones), some of which have shown anticancer activity and/or DNA damaging effects. Here we report that 2-furanone and 2-pyrone induce cellular DNA damage (assessed by the comet assay and the gamma-H2AX focus assay) and the formation of topoisomerase I- and topoisomerase II-DNA complexes in cells (visualized and quantified in situ by the TARDIS assay). Cells mutated in BRCA2 (deficient in homologous recombination repair) were significantly hypersensitive to the cytotoxic activity of 2-pyrone, therefore suggesting that BRCA2 plays an important role in the repair of DNA damage induced by this lactone. Both lactones were cytotoxic in A549 lung cancer cells at lower concentrations than in MRC5 non-malignant lung fibroblasts. The possible involvement of 2-furanone and 2-pyrone in the anticancer and DNA-damaging activities of compounds containing these lactones is discussed.