Rat liver sub-mitochondrial particles produce hydroxyl radicals when exposed to NADH and Rifamycin S, with NADH dehydrogenase (complex I) playing a key role in Rifamycin S reduction. NADH is nearly as effective as NADPH in catalyzing the interaction of these antibiotics with rat liver microsomes. Rifamycin S undergoes reduction to Rifamycin SV, a hydroquinone, by Fe(II), forming a detectable Fe(II)-(Rifamycin S)3 complex. Rifamycin S inhibits Fe:ATP-induced lipid peroxidation completely. It undergoes redox-cycling with rat liver microsomes, leading to hydroxyl radical production in the presence of iron complexes ^[1].

The bacteriostatic effect of Rifamycin SV stems from the generation of active oxygen species through its oxidation-reduction cycle within cells. Metal ions, including Mn²⁺, Cu²⁺, and Co²⁺, induce the aerobic oxidation of Rifamycin SV to Rifamycin S, with Mn²⁺ being the most potent catalyst ^[2].