Antitumor effects of volatile components of Magnolia salicifolia essential oil against breast cancer cells are mediated via mitochondrial apoptosis

Background Plant essential oils exhibit anticancer properties. However, the antitumor effects of Magnolia salicifolia essential oil remain unexplored. Methods We evaluated the antitumor activities of M. salicifolia essential oil and its volatile components in 4T1 murine breast cancer cells. Cell viability was assessed using the MTT assay. The concentration of the volatile components was analyzed using gas chromatography (GC)-mass spectrometry (MS). Morphological changes in the cells were examined using fluorescence microscopy. The underlying mechanisms regarding the antitumor effects of M. salicifolia essential oil were investigated using western blotting. Results M. salicifolia essential oil exhibited potent antitumor activity with a Half maximal inhibitory concentration (IC50) of 1.05 µg/mL in 4T1 cells. The antitumor effects of the volatile components decreased in a distance-dependent manner. GC-MS analysis revealed that the oil contained high levels of citral (neral + geranial), 1,8-cineole, and transanethole. Citral demonstrated significantly stronger antitumor activity than 1,8-cineole (IC50 = 1.93 vs. 68.4 µg/mL; n=3 independent experiments per condition). In vivo , inhalation of M. salicifolia essential oil vapor significantly reduced tumor incidence (7 of 15 mice, 47% vs. 14 of 15 mice, 93% in controls; Fisher’s exact test, p=0.0142) and tumor area and weight (n=15 mice/group, p<0.005), without affecting body weight. Mechanistically, citral induced apoptosis via mitochondrial dysfunction, characterized by a decrease in membrane potential, increased cytochrome c levels, and activation of caspase-3 and caspase-9. Comparable antitumor activity was confirmed in the human breast cancer cell line MCF-7, with IC50 values of 1.021 µg/mL for the essential oil and 1.285 µg/mL for citral, supporting the translational relevance of these findings. In addition, M. salicifolia essential oil exhibited preferential cytotoxicity toward 4T1 cancer cells over the non-tumorigenic MCF-10A mammary epithelial cell line, indicating cancer-selective activity. Conclusion The volatile components of M. salicifolia essential oil exert strong antitumor effects primarily through citral-mediated mitochondrial apoptosis. These findings highlight the potential of inhaled phytochemicals as novel anticancer agents.