N-Boc-L-tyrosine

In this study, we synthesized five N-Boc-L-tyrosine-based analogues to glitazars. The in vitro effects of compounds 1-5 on protein tyrosine phosphatase 1B (PTP-1B), peroxisome proliferator-activated receptor alpha and gamma (PPARα/γ), glucose transporter type-4 (GLUT-4) and fatty acid transport protein-1 (FATP-1) activation are reported in this paper. Compounds 1 and 3 were the most active in the in vitro PTP-1B inhibition assay, showing IC50s of approximately 44 μM. Treatment of adipocytes with compound 1 increased the mRNA expression of PPARγ and GLUT-4 by 8- and 3-fold, respectively. Moreover, both compounds (1 and 3) also increased the relative mRNA expression of PPARα (by 8-fold) and FATP-1 (by 15-fold). Molecular docking studies were performed in order to elucidate the polypharmacological binding mode of the most active compounds on these targets. Finally, a murine model of hyperglycemia was used to evaluate the in vivo effectiveness of compounds 1 and 3. We found that both compounds are orally active using an exploratory dose of 100 mg/kg, decreasing the blood glucose concentration in an oral glucose tolerance test and a non-insulin-dependent diabetes mellitus murine model. In conclusion, we demonstrated that both molecules showed strong in vitro and in vivo effects and can be considered polypharmacological antidiabetic candidates.

The developments in the use of plasmid DNA (pDNA) in gene therapy and vaccines have motivated the search and improvement of optimized purification processes. In this context, dipeptides l-tyrosine-l-tyrosine and l-tyrosine-l-arginine are synthetized to explore their application as affinity ligands for supercoiled (sc) plasmid DNA (pDNA) purification. The synthesis is based on the protection of N-Boc-l-tyrosine, followed by condensation with l-tyrosine or l-arginine methyl esters in the presence of dicyclohexylcarbodiimide (DCC), which after hydrolysis and acidification give the afforded dipeptides. The supports are then obtained by coupling l-tyrosine, l-tyrosine-l-tyrosine and l-tyrosine-l-arginine to epoxy-activated Sepharose and are characterized by high resolution magic angle spinning (HR-MAS) NMR and Fourier transform infrared spectroscopy (FTIR). Surface plasmon resonance (SPR) biosensor is used to establish the promising ligand to be used in the chromatographic experiments and ascertain experimental conditions. Sc isoform showed the highest affinity to the dipeptides, followed by linear (ln) pDNA, being the open circular (oc) the one that promoted the lowest affinity to l-tyrosine-l-arginine. Saturation transfer difference (STD)-NMR experiments show that the interaction is mainly hydrophobic with the majority of the 5'-mononucleotides, except for 5'-GMP with l-tyrosine-l-arginine Sepharose that is mainly electrostatic. The support l-tyrosine Sepharose used in chromatographic experiments promotes the separation of native pVAX1-LacZ and pcDNA3-FLAG-p53 samples (oc+sc) by decreasing the salt concentration. The results suggest that it is possible to purify different plasmids with the l-tyrosine Sepharose, with slight adjustments in the gradient conditions.

N,N'-diBoc-dityrosine (DBDY), which was synthesized by the oxidative C-C coupling of 2 N-Boc-L-tyrosine molecules, was conjugated with two isoniazid (INH) molecules. Due to the quenching effect of INH, DBDY-(INH)(2) lacks the fluorescence of DBDY. As such, it was tested for use in the detection of proteases by measuring fluorescence recovery. In this study, serine proteases (chymotrypsin, trypsin, subtilisin, and proteinase K), metalloproteases (thermolysin and carboxypeptidase A, dispase, and collagenase), aspartic proteases (pepsin and aspergillopepsin) and cysteine proteases (papain and chymopapain) were chosen. Reported optimum assay conditions were chosen for each enzyme. Only papain and chymopapain catalyzed the hydrolysis of DBDY-(INH)(2) and led to fluorescence recovery, possibly due to their extensive binding sites and the INH-mediated inhibition of metalloproteases and aspartic proteases.