Therapeutic potential of mitochonic acid (MA-5) in modulating mitochondrial function and inflammatory responses: A focus on carnitine/acylcarnitine carrier (SLC25A20) transport activity

The mitochondrial carnitine/acylcarnitine carrier (CAC, SLC25A20) is sensitive to mitochonic acid (MA-5), a synthetic derivative of the plant hormone indole-3-acetic acid. The effect of the drug on the transport activity of the native (rat liver mitochondrial extract) and recombinant CAC WT (wild-type) protein, overexpressed in E. coli, was tested using the proteoliposome tool together with computational analysis (molecular docking method and molecular dynamics simulation - MDS). Dose-response analysis of MA-5 inhibition on both the native and recombinant protein revealed IC50 values of 73 ± 4.4 μM and 58 ± 12 μM, respectively. Kinetic studies on the recombinant protein (WT) indicated a non-competitive inhibition, which was further confirmed by protection experiments. Additionally, the inhibition was reversible after a prolonged incubation time with MA-5; the rate of drug release was also dependent on the length of the carnitine derivatives (acetylcarnitine, decanoylcarnitine, palmitoylcarnitine). Protection of transport activity by MA-5 under conditions of oxidative stress (caused by H2O2 or atmospheric O2) was investigated. The potential therapeutic implications of MA-5 are discussed.