Anthocyanins: From plant pigments to health benefits at mitochondrial level

Anthocyanins are water-soluble pigments providing certain color for various plant parts, especially in edible berries. Earlier these compounds were only known as natural food colorants, the stability of which depended on pH, light, storage temperature and chemical structure. However, due to the increase of the in vitro, in vivo experimental data, as well as of the epidemiological studies, today anthocyanins and their metabolites are also regarded as potential pharmaceutical compounds providing various beneficial health effects on either human or animal cardiovascular system, brain, liver, pancreas and kidney. Many of these effects are shown to be related to the free-radical scavenging and antioxidant properties of anthocyanins, or to their ability to modulate the intracellular antioxidant systems. However, it is generally overlooked that instead of acting exclusively as antioxidants certain anthocyanins affect the activity of mitochondria that are the main source of energy in cells. Therefore, the aim of the present review is to summarize the major knowledge about the chemistry and regulation of biosynthesis of anthocyanins in plants, to overview the facts on bioavailability, and to discuss the most recent experimental findings related to the beneficial health effects emphasizing mitochondria

Modification of Permeability Transition Pore Arginine(s) by Phenylglyoxal Derivatives in Isolated Mitochondria and Mammalian Cells. Structure-function relationship of arginine ligands

Methylglyoxal and synthetic glyoxal derivatives react covalently with arginine residue(s) on the mitochondrial permeability transition pore (PTP). In this study, we have investigated how the binding of a panel of synthetic phenylglyoxal derivatives influences the opening and closing of the PTP. Using both isolated mitochondria and mammalian cells, we demonstrate that the resulting arginine-phenylglyoxal adduct can lead to either suppression or induction of permeability transition, depending on the net charge and hydrogen bonding capacity of the adduct. We report that phenylglyoxal derivatives that possess a net negative charge and/or are capable of forming hydrogen bonds induced permeability transition. Derivatives that were overall electroneutral and cannot form hydrogen bonds suppressed permeability transition. When mammalian cells were incubated with low concentrations of negatively charged phenylglyoxal derivatives, the addition of oligomycin caused a depolarization of the mitochondrial membrane potential. This depolarization was completely blocked by cyclosporin A, a PTP opening inhibitor, indicating that the depolarization was due to PTP opening. Collectively, these findings highlight that the target arginine(s) is functionally linked with the opening/ closing mechanism of the PTP and that the electric charge and hydrogen bonding of the resulting arginine adduct influences the conformation of the PTP. These results are consistent with a model where the target arginine plays a role as a voltage sensor

Modification of Permeability Transition Pore Arginine(s) by Phenylglyoxal Derivatives in Isolated Mitochondria and Mammalian Cells: Structure-Function Relationship of Arginine Ligands

Methylglyoxal and synthetic glyoxal derivatives react covalently with arginine residue(s) on the mitochondrial permeability transition pore (PTP). In this study, we have investigated how the binding of a panel of synthetic phenylglyoxal derivatives influences the opening and closing of the PTP. Using both isolated mitochondria and mammalian cells, we demonstrate that the resulting arginine-phenylglyoxal adduct can lead to either suppression or induction of permeability transition, depending on the net charge and hydrogen bonding capacity of the adduct. We report that phenylglyoxal derivatives that possess a net negative charge and/or are capable of forming hydrogen bonds induced permeability transition. Derivatives that were overall electroneutral and cannot form hydrogen bonds suppressed permeability transition. When mammalian cells were incubated with low concentrations of negatively charged phenylglyoxal derivatives, the addition of oligomycin caused a depolarization of the mitochondrial membrane potential. This depolarization was completely blocked by cyclosporin A, a PTP opening inhibitor, indicating that the depolarization was due to PTP opening. Collectively, these findings highlight that the target arginine(s) is functionally linked with the opening/ closing mechanism of the PTP and that the electric charge and hydrogen bonding of the resulting arginine adduct influences the conformation of the PTP. These results are consistent with a model where the target arginine plays a role as a voltage sensor