ABSTRACT
The group of 19 thiosemicarbazones (TSCs) were synthesized and its inhibitory activity toward mushroom tyrosinase and ability to inhibition of melanogenesis in B16 cells were investigated. Moreover, molecular docking of these compounds to the active site of the enzyme was performed. The obtained results allowed to make the structure-activity relationship (SAR) analysis. Kinetic studies revealed that TSCs 1, 2, 11 and 18 have better inhibitory properties than kojic acid, a reference compound, with the best inhibitory constant (Ki) value of 0.38⯵M for TSC 2. According to SAR analysis, the smaller and less branched molecules exhibit higher affinity to the enzyme. Melanin production in B16 cells was inhibited by all investigated compounds at micromolar level. Most of compounds studied in this work can be considered as potent inhibitors of tyrosinase and melanogenesis. They may have broad application in food preservatives and cosmetics. Combined results of molecular docking and SAR analysis can be helpful in designing novel tyrosinase inhibitors of desired properties.
Subject(s)
Agaricales/enzymology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Melanins/antagonists & inhibitors , Monophenol Monooxygenase/antagonists & inhibitors , Thiosemicarbazones/chemistry , Thiosemicarbazones/pharmacology , Agaricus/enzymology , Animals , Biosynthetic Pathways/drug effects , Cell Line, Tumor , Melanins/metabolism , Mice , Molecular Docking Simulation , Monophenol Monooxygenase/metabolismABSTRACT
Two series of dehydropeptides of the general formulae Boc-Gly-X-Phe-p-NA, Boc-Gly-Gly-X-Phe-p-NA, Gly-X-Gly-Phe-p-NA.TFA, and Boc-Gly-X-Gly-Phe-p-NA, with X = Delta(Z)Phe and DeltaAla, were studied with NMR in DMSO and CDCl(3)-DMSO, and with CD in MeOH, MeCN, and TFE. The NMR spectra measured in DMSO suggest that peptides with the DeltaPhe residue next to Phe are folded whereas peptides with Gly between DeltaPhe and Phe are less ordered. NMR spectra of DeltaAla-containing peptides indicate that these peptides are flexible and their conformational equilibria are populated by many different conformations. The CD spectra show that conformational properties of the peptides studied are distinctly influenced by a mutual position of the dehydroamino acid residue and the p-NA group. They indicate that all dehydropeptides with the DeltaPhe residue, Boc-Gly-DeltaAla-Phe-p-NA, and Boc-Gly-Gly-DeltaAla-Phe-p-NA adopt ordered conformations in all solvents studied, presumably of the beta-turn type. The last two peptides exhibit surprising chiroptical properties. Their spectra show exciton coupling-like couplets in the region of the p-NA group absorption. This shape of CD spectra suggests a rigid, chiral conformation with a fixed disposition of the p-NA group. The CD spectra indicate that Boc-Gly-DeltaAla-Gly-Phe-p-NA and Gly-DeltaAla-Gly-Phe-p-NA.TFA are unordered, independently of the solvent.
Subject(s)
Alanine/analogs & derivatives , Amides/chemistry , Dipeptides/chemistry , Models, Chemical , Phenylalanine/analogs & derivatives , Alanine/chemistry , Circular Dichroism , Crystallography , Magnetic Resonance Spectroscopy , Models, Molecular , Phenylalanine/chemistry , Protein Conformation , Spectroscopy, Fourier Transform InfraredABSTRACT
Synthesis, structural and biological studies of pentapeptides containing two DeltaPhe residues (Z and E isomers) in position 2 and 4 in peptide chain were performed. All the investigated peptides adopted bent conformation and majority of them could exist as two different conformers in solution. Only pentapeptides, containing free N-termini appeared to act as weak inhibitors of cathepsin C with the slow-binding, competitive mechanism of inhibition, free acids being bound slightly better than their methyl esters. Results of molecular modeling suggested significant difference between peptides, depending of the type of amino acid residue in position 5 in peptide chain. Dehydropeptides containing Gly residue in this position may act as competitive slow-reacting substrates and therefore exhibit inhibitory-like properties.
Subject(s)
Cathepsin C/antagonists & inhibitors , Cathepsin C/metabolism , Oligopeptides/chemistry , Oligopeptides/chemical synthesis , Phenylalanine/analogs & derivatives , Binding, Competitive/physiology , Magnetic Resonance Spectroscopy , Models, Molecular , Oligopeptides/physiology , Phenylalanine/chemistry , Phenylalanine/metabolism , Phenylalanine/physiology , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacology , Protein Structure, Secondary , Substrate Specificity/physiologyABSTRACT
Three dehydrotetrapeptides of rationally varying structure were prepared and tested as affectors of cathepsin C. These compounds appeared to be substrates of the enzyme, being equipotent with their classical counterparts. Thus, replacement of amino acid in a short peptide by corresponding dehydroamino acid does not prevent cathepsin C in recognizing dehydropeptide as its substrate.