Galaxolide and Tonalide induce the degeneration of (A) human lung cancer A549 cells and (B) human neuroblastoma SH-SY5Y cells in a concentration-dependent manner. A549 cells (2.5 × 106 cells/mL) were cultured and seeded in 96-well plates containing serum-free RPMI 1640/F12 medium as described in the methods. The cells were initially treated with Tonalide and Galaxolide (1–200 µM) followed by supplementation with the same amounts of compounds at 0, 24, and 48 h. At 48 h after treatment with the indicated concentrations of the respective compounds, cell viability was measured by fluorescence using the resazurin reduction assay. Both compounds induced the degeneration of cells in a concentration-dependent manner. The results are expressed as the means (±SEM, N = 4) relative to the control untreated cells. *P < 0.05, **P < 0.01, and ***P < 0.001 versus untreated control cells compared by ANOVA, followed by the Dunnett’s post-test.