S-15176 is an inhibitor of the mitochondrial permeability transition pore (PTP). It effectively suppresses mitochondrial swelling induced by tert-butyl hydroperoxide, with an IC50 value of 45.7 μM. S-15176 prevents the opening of PTP, thus averting the dissipation of mitochondrial membrane potential and the oxidation of NAD(P)H, while enhancing mitochondrial calcium loading capacity. It holds potential for research into ischemia-reperfusion injury.