2',6'-dimethylphenylalanine: a useful aromatic amino Acid surrogate for tyr or phe residue in opioid peptides

Synthesis of 2,6-Dimethyltyrosine-Like Amino Acids through Pinacolinamide-Enabled C-H Dimethylation of 4-Dibenzylamino Phenylalanine

The synthesis of a small library of NH-Boc- or NH-Fmoc-protected l-phenylalanines carrying methyl groups at positions 2 and 6 and diverse functionalities at position 4 has been achieved. The approach, which took advantage of a Pd-catalyzed directed C-H dimethylation of picolinamide derivatives, allowed the electronic and steric properties of the resulting amino acid derivatives to be altered by appending a variety of electron-withdrawing, electron-donating, or bulky groups.

The Role Of Amino Acid Arginine And Nitric Oxide System In Implementing Cardioprotective Effect Of Non-Opioid Analogue Of Leu-Enkephalin In Newborn Albino Rats After Intrauterine Hypoxia

Objective ― to evaluate the role of the amino acid arginine in the structure of the non-opioid analogue of leu-enkephalin (NALE) and the involvement of the nitric oxide system in the implementation of its cardioprotective effect in newborn albino rats subjected to intrauterine hypoxia. Material and Methods ― Pregnant female rats were subjected daily to 4-hour hypobaric hypoxia (oxygen partial pressure – 65 mm Hg) on days 15-19 of their gestation. The 7-day-old offspring of hypoxified female rats were examined. The progeny of intact animals served the control. We studied body and heart weights; activity of proliferative processes and autophagy in the myocardium of subendocardial parts of the left ventricle, expressed via the immunohistochemical detection of Ki-67 and Beclin-1 proteins, respectively; karyometric and nucleolometric indicators of cardiomyocytes (CMC); intensity of free radical processes in the tissues of the heart by chemiluminescence parameters. Correction of post-hypoxic changes in newborn rats was carried out by intraperitoneal injection of two peptides (Phe–D-Ala–Gly–Phe–Leu–Arg – non-opioid analogue of leu-enkephalin, or NALE, and Phe–D-Ala–Gly–Phe–Leu–Gly – G peptide) daily from day 2 through day 6 of their lives at a dose of 100 μg/kg. To assess the involvement of the nitric oxide system in the implementation of the NALE effects, the NO synthase inhibitor – N-nitro-L-arginine methyl ester (L-NAME) was additionally administered at a dose of 50 mg/kg. Results ― Intrauterine hypoxia led to a decrease in body weights of 7-day-old animals, an increase in the number of CMC expressing the Beclin-1 protein, reduction in the size of CMC nuclei, activation of free radial oxidation, and a decrease in antiradical protection in the heart tissues. The administration of NALE to newborn animals, subjected to intrauterine hypoxia (IUH), normalized their body weight and size of the CMC nuclei, and partially corrected changes in Beclin-1 expression and in chemiluminescence parameters. In 7-day-old animals, subjected to IUH and neonatal administration of NALE and L-NAME, a lower body weight was observed than in the control. Against the background of nitric oxide blockade, the antioxidant effect of NALE diminished, but the corrective effect of NALE on the karyometric index and Beclin-1 expression remained. G peptide, which differs from NALE by the substitution of the C-terminal amino acid Arg for the amino acid Gly, exhibited a corrective effect similar to NALE on the consequences of IUH. Conclusion ― Administration of NALE and G peptides to newborn albino rats after IUH has a pronounced cardioprotective effect. The mechanisms of the NALE peptide effects are, in part, associated with the activation of the NOS-NO system. However, the affinity of this peptide for opioid-like receptors may be of greater importance.

Mitochondria-Targeted Triphenylphosphonium-Based Compounds: Syntheses, Mechanisms of Action, and Therapeutic and Diagnostic Applications

Mitochondria are recognized as one of the most important targets for new drug design in cancer, cardiovascular, and neurological diseases. Currently, the most effective way to deliver drugs specifically to mitochondria is by covalent linking a lipophilic cation such as an alkyltriphenylphosphonium moiety to a pharmacophore of interest. Other delocalized lipophilic cations, such as rhodamine, natural and synthetic mitochondria-targeting peptides, and nanoparticle vehicles, have also been used for mitochondrial delivery of small molecules. Depending on the approach used, and the cell and mitochondrial membrane potentials, more than 1000-fold higher mitochondrial concentration can be achieved. Mitochondrial targeting has been developed to study mitochondrial physiology and dysfunction and the interaction between mitochondria and other subcellular organelles and for treatment of a variety of diseases such as neurodegeneration and cancer. In this Review, we discuss efforts to target small-molecule compounds to mitochondria for probing mitochondria function, as diagnostic tools and potential therapeutics. We describe the physicochemical basis for mitochondrial accumulation of lipophilic cations, synthetic chemistry strategies to target compounds to mitochondria, mitochondrial probes, and sensors, and examples of mitochondrial targeting of bioactive compounds. Finally, we review published attempts to apply mitochondria-targeted agents for the treatment of cancer and neurodegenerative diseases.