This study aimed to analyze the effects of salt stress on the growth physiology and plant-cell ultrastructure of Isatis indigotica Fort. (I. indigotica) to evaluate its adaptability under salt stress. The effects of different concentrations of salt (NaCl; 0, 25, and 300 mmol·L⁻¹) on the agronomic traits, activities of related enzymes, ion balance, and mesophyll-cell ultrastructure of I. indigotica were studied in a controlled pot experiment. Results showed that compared with those of the control group, the aerial-part fresh weight, underground fresh weight, tiller number, root length, root diameter, plant height, and leaf area of salt-stressed I. indigotica increased at 25 mmol·L⁻¹ and then decreased at 300 mmol·L⁻¹. The changes in levels of superoxide dismutase, peroxidase, ascorbate peroxidase, and catalase showed a similar trend, with significant differences compared with control group. Salt stress altered the ion balance of I. indigotica, resulting in a significant increase in Na⁺ content and a significant decrease in K⁺ content. The contents of Ca²⁺ and Mg²⁺ changed to varying degrees. The analysis of the microstructure of the root showed that under salt treatment, the epidermal cells of the root significantly thickened and the diameter of the xylem decreased. The results of ultrastructural analysis of mesophylls showed that salt stress can cause cell-membrane contraction, cell-gap enlargement, disorder in the structures of chloroplasts and mitochondria, and an increase in the number of osmiophilic particles. These changes were aggravated by the increase in NaCl concentration. This study reveals the response of I. indigotica to salt stress and provides a basis for further study on the salt-tolerance mechanism of I. indigotica.

Panaxadiol (PD) is a bioactive dammarane triterpenoid with limited antiproliferative potency, and systematic optimization of its C3 and C12 positions remains underexplored. Here, a stepwise, site-differentiated strategy was established by combining selective C3 esterification with late-stage C12 diversification through a chloroacetyl–piperazine linker, affording 23 PD derivatives and enabling complementary C3/C12 structure–activity analysis. Antiproliferative screening in AGS gastric cancer cells identified compounds 6, 11, and 17 as the most active analogues, with IC₅₀ values of 8.41, 5.08, and 6.78 μM, respectively, all outperforming 5-fluorouracil under identical conditions. Compound 6 provided a relatively favorable balance between low-micromolar activity and preservation of non-malignant GES-1 cells within a defined concentration range and was therefore selected for mechanistic investigation. Transcriptomic profiling identified 298 differentially expressed genes associated with cellular stress, cytokine signaling, epithelial growth regulation, and extracellular remodeling, whereas metabolomic analysis revealed marked perturbation of glycerophospholipid, choline, polyunsaturated fatty acid, and glutathione metabolism. Integrated analysis highlighted membrane-lipid remodeling, redox dysregulation, and ferroptosis-related processes as central features of the response. These findings establish a modular platform for PD optimization and identify compound 6 as a promising lead for further anti-gastric cancer development.