PI3K/AKT-IN-4 (compound 3), a diterpenoid extracted from the roots and rhizomes of Salvia castanea Dielsf., exhibits antitumor properties by inhibiting cell viability and proliferation (IC 50 =4.72 μM) and promoting apoptosis in Hep3B cells. This compound obstructs the G0/G1 phase of the cell cycle, triggers mitochondrial dysfunction, and induces oxidative stress. Moreover, PI3K/AKT-IN-4 combats hepatocellular carcinoma through the inhibition of the PI3K-Akt signaling pathway and by interacting with PARP1 and CDK2 targets.