(-)-Epi-Osmundalactone-Rich Fraction from Suppresses Proliferation and Induces Intrinsic Apoptosis in Non-Small Cell Lung Cancer Cells via MAPK Pathway Modulation.

Non-small cell lung cancers (NSCLCs), most notably adenocarcinoma and large cell carcinoma, have been the most frequently diagnosed lung cancer and continue to represent a leading cause of cancer-related mortality worldwide, largely due to its aggressive growth and limited therapeutic responsiveness. Natural products derived from traditional medicinal plants remain a valuable source for the discovery of novel anti-cancer agents. In this study, the anti-cancer potential of (G. Forst.) Hoffm., a medicinal fern widely used in Thai traditional medicine, was investigated in human NSCLC, A549 and H1299 cells. Subsequential solvent extraction yielded hexane, ethyl acetate, and ethanol fractions, among which the ethyl acetate extract (AE-EA) exhibited the strongest growth inhibitory activity. Bioactivity-guided fractionation of AE-EA by thin-layer chromatography generated an (-)-epi-osmundalactone-rich fraction (OLRF), which contained three closely related lactone/furanone derivatives, with (-)-epi-osmundalactone as the predominant constituent, as determined by NMR analysis. AE-EA and OLRF significantly suppressed NSCLC cell viability and clonogenic survival and induced G0/G1 cell cycle arrest, accompanied by downregulation of cyclin D1, cyclin E1, CDK-2, and CDK-4 ( < 0.05). Both treatments also triggered intrinsic apoptosis, as evidenced by mitochondrial membrane depolarization, reduced expression of Bcl-2, and Bcl-xL, and survivin, and activation of cleaved caspase-9 and caspase-3. Mechanistically, AE-EA and OLRF significantly suppressed mitogen-activated protein kinase (MAPK) signaling through inhibition of ERK1/2, JNK1/2, and p38 phosphorylation in both NSCLC cells ( < 0.05). Collectively, these findings demonstrate that AE-EA and OLRF exert pronounced anti-cancer effects in both NSCLC cells through coordinated inhibition of MAPK signaling, induction of cell-cycle arrest, and activation of intrinsic apoptosis, supporting their potential for further development as plant-derived anti-cancer agents.