Abstract

The interaction between cytochrome c (Cyt c) and cardiolipin (CL) within the inner mitochondrial membrane is a critical event in the intrinsic apoptotic pathway, leading to the formation of a Cyt c–CL complex with potent peroxidase activity. This complex catalyzes the oxidation of CL, a key step in initiating mitochondrial outer membrane permeabilization and subsequent release of pro-apoptotic factors. Understanding the precise mechanisms that regulate this peroxidase activity is essential for developing therapeutic strategies targeting mitochondrial dysfunction. This study investigates the use of quinolizidine derivatives of coumarin as novel molecular probes to elucidate the action mechanisms of the Cyt c–CL complex. We hypothesize that these derivatives, known for their fluorescent and redox properties, can serve as substrates or inhibitors to characterize the enzymatic kinetics and structural changes of the complex. Using spectrophotometric and chemiluminescence methods, the study demonstrates that quinolizidine coumarins act as substrates for the peroxidase activity of the Cyt c–CL complex, with varying efficiencies dependent on their specific chemical structure. The results suggest that these compounds can effectively compete with endogenous substrates, providing a new tool for studying the active site and reaction pathway of the complex. Furthermore, the findings offer a foundation for the rational design of novel compounds that can modulate the peroxidase activity of the Cyt c–CL complex, potentially leading to new agents for regulating apoptosis and treating diseases associated with mitochondrial stress.