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.
Subject(s)
Antioxidants/administration & dosage , Drug Delivery Systems/methods , Mitochondria/metabolism , Organophosphorus Compounds/administration & dosage , Plastoquinone/analogs & derivatives , Ubiquinone/analogs & derivatives , Animals , Antioxidants/pharmacokinetics , Antioxidants/therapeutic use , Humans , Mitochondria/drug effects , Mitochondria/pathology , Organophosphorus Compounds/pharmacokinetics , Organophosphorus Compounds/therapeutic use , Oxidative Stress/drug effects , Plastoquinone/administration & dosage , Plastoquinone/pharmacokinetics , Plastoquinone/therapeutic use , Reactive Oxygen Species/metabolism , Ubiquinone/administration & dosage , Ubiquinone/pharmacokinetics , Ubiquinone/therapeutic useABSTRACT
The mitochondria-targeted antioxidant SkQR1 composed of a plastoquinone part covalently bound to a cationic rhodamine 19 moiety via a decane linker was previously shown to effectively protect brain and kidney from ischemia injury accompanying generation of reactive oxygen species. In the present paper the energy-dependent SkQR1 uptake by isolated rat liver mitochondria was studied by fluorescence correlation spectroscopy peak intensity analysis (FCS PIA). This approach can be used to measure the number of fluorescent molecules per single mitochondrion. A large portion of SkQR1 appeared to be taken up by mitochondria in an energy-independent fashion because of its high affinity to membranes. Liposomes were found to compete effectively with mitochondria for the energy-independent SkQR1 binding, thereby facilitating, as an "SkQR1-buffer", observation of energy-dependent SkQR1 accumulation in mitochondria. The rate of energy-dependent SkQR1 uptake by mitochondria observed in the presence of liposomes was rather low (minutes) which was apparently due to slow redistribution of SkQR1 between liposomal and mitochondrial membranes. This can explain the low rate of staining of mitochondria by SkQR1 in living cells containing, besides mitochondria, other membrane components (endoplasmic reticulum, Golgi membranes, endosomes, lysosomes, etc.) which can compete with mitochondria for the energy-independent SkQR1 binding.
