Glioma, a common primary brain tumor, is highly infiltrative and invasive, often leading to drug resistance and recurrence. Therefore, the development of novel therapeutic agents is urgently needed. Pseudellone C is a novel marine triindole alkaloid. Screening of its antiproliferative activity against 55 cell lines revealed its anti-CNS cancer potential. A total of 42 derivatives of Pseudellone C were designed and synthesized, and their inhibitory activities against two human glioma cell lines (U-87MG and LN-229) were evaluated using the CCK-8 assay. Ten derivatives exhibited potent antiproliferative activity with IC50 values below 10 mu mol, which are 18- to 39fold more potent than Pseudellone C. Among these, derivative 4o demonstrated favorable blood-brain barrier permeability. Mechanistic studies revealed that 4o induces apoptosis primarily by activating the downstream caspase 3 cascade via the TNF/TNFR pathway. Structure-activity relationship correlations were systematically analyzed, and a pharmacophore model for further rational design was constructed.