phomoxanthone A

Phomoxanthone A (PXA) is a natural tetrahydroxanthone dimer isolated from the endophytic fungus *Phomopsis longicolla*. It exhibits potent anti-tumor activity, particularly against cisplatin-resistant solid cancer cell lines such as ovarian and bladder cancer. The compound acts by inducing rapid depolarization of the mitochondrial membrane potential, which triggers the activation of executioner caspases 3 and 7, leading to programmed cell death (apoptosis). Notably, PXA maintains its efficacy in platinum-resistant cells, suggesting it bypasses common resistance mechanisms. Research indicates that PXA can penetrate the inner mitochondrial membrane without causing non-specific plasma membrane damage or altering intracellular reactive oxygen species (ROS) levels, positioning it as a potential lead compound for treating clinically resistant malignancies.