Mitochondria-Targeted Drugs

Abstract

Background: Targeting of drugs to the subcellular compartments represents one of the modern trends in molecular pharmacology. The approach for targeting mitochondria was developed nearly 50 years ago, but only in the last decade has it started to become widely used for delivering drugs. A number of pathologies are associated with mitochondrial dysfunction, including cardiovascular, neurological, inflammatory and metabolic conditions.

Objective: This mini-review aims to highlight the role of mitochondria in pathophysiological conditions and diseases, to classify and summarize our knowledge about targeting mitochondria and to review the most important preclinical and clinical data relating to the antioxidant lipophilic cations MitoQ and SkQ1.

Methods: This is a review of available information in the PubMed and Clinical Trials databases (US National Library of Medicine) with no limiting period.

Results and conclusion: Mitochondria play an important role in the pathogenesis of many diseases and possibly in aging. Both MitoQ and SkQ1 have shown many beneficial features in animal models and in a few completed clinical trials. More clinical trials and research efforts are needed to understand the signaling pathways influenced by these compounds. The antioxidant lipophilic cations have great potential for the treatment of a wide range of pathologies.

Keywords: Mitochondria; antioxidants; metabolic syndrome; reactive oxygen species; targeted drug delivery; uncouplers of oxidative phosphorylation..

Fig. (1)

Scheme of mitochondrial electron transport chain (ETC). Electron flow (black arrows) from NADH or FADH₂ substrates through complexes I - IV of ETC is accompanied by pumping of protons. This results in a proton gradient between the inner mitochondrial membrane (IMM) and the outer mitochondrial membrane (OMM). This proton-motive force is used by ATP synthase (complex V) to make ATP from ADP and a phosphate (Pi). Abbreviations: Q - coenzyme Q10, c - cytochrome c.

Fig. (2)

Three main types of mitochondrial targeting. Mitochondrial uptake of lipophilic cations such as triphenylphosphonium (TPP) occurs due to the transmembrane potential (ΔΨm), and the cations are accumulated at the inner mitochondrial membrane. Peptides penetrating mitochondria and binding to the mitochondrial phospholipid cardiolipin (CL). Cellular proteins with N-terminal mitochondrial targeting sequences are imported into mitochondria via TOM and TIM channels.

Fig. (3)

Chemical structures of the lipophilic cations triphenylphosphonium (TPP), MitoQ and SkQ1. MitoQ and SkQ1 are shown in the oxidized (quinone) forms.