ABSTRACT
Cathepsins have emerged as important targets in various tissues degenerative disorders due to their involvement in degradation of extracellular matrices and endogenous protein turnover. Elevated cathepsins levels vis-à-vis decreased concentration of endogenous inhibitors has been reported at different diseased sites. The design and synthesis of specific potential anti-cathepsin agents is therefore of great significance. Most of potential anti-cathepsin agents developed have peptide based structures with an active warhead. Due to oral instability and immunogenic problems related to peptidyl inhibitors drift the synthesis and evaluation of non-peptide cathepsin inhibitors in last two decades. The present work provides a detailed structure activity relationship for developing potential non-peptide anticathepsin agents based on in-vitro inhibition studies of a library of synthesized thiocarbamoyl- non-peptide inhibitors.
Subject(s)
Cathepsin B/antagonists & inhibitors , Cathepsin H/antagonists & inhibitors , Cathepsin L/antagonists & inhibitors , Protease Inhibitors/pharmacology , Thiocarbamates/pharmacology , Cathepsin B/isolation & purification , Cathepsin B/metabolism , Cathepsin H/isolation & purification , Cathepsin H/metabolism , Cathepsin L/isolation & purification , Cathepsin L/metabolism , Dose-Response Relationship, Drug , Humans , Molecular Structure , Protease Inhibitors/chemical synthesis , Protease Inhibitors/chemistry , Structure-Activity Relationship , Thiocarbamates/chemical synthesis , Thiocarbamates/chemistryABSTRACT
Cysteine Cathepsins well known to be involved in cancer, inflammation and regulation of degenerative processes like apoptosis have become specific targets in drug designing. The potential of quinazolines and their derivatives in medicinal chemistry led us to synthesise a novel series of seven compounds of quinazolines to evaluate their effect on cathepsins and cellular aspects of HepG2 cells. In the present work we report the solvent free microwave assisted synthesis of (E)-8-benzylidene-5,6,7,8-tetrahydro-2,4-diarylquinazolines as inhibitors of mammalian hepatic cysteine proteases viz. Cathepsins B, H and L. In vitro inhibition of Cathepsins B, H and L is correlated well with in vitro studies when tested using MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay on HepG2 cells, hepatocellular carcinoma cell line. The studies have been extended to evaluate the type of inhibition exhibited by the individual enzyme. Out of the seven compounds 1g i.e. (E)-8-(4-fluorobenzylidene)-4-(4-fluorophenyl)-2-phenyl-5, 6, 7, 8-tetrahydroquinazoline has been found to be most inhibitory for Cathepsins B, H and L to a maximum extent with the Ki values of 10-10M, 10-10M and 10-9M order respectively. In silico studies of all compounds have also been done at the active sites of Cathepsin B, H and L.
Subject(s)
Antineoplastic Agents/chemical synthesis , Cathepsin B/antagonists & inhibitors , Cathepsin H/antagonists & inhibitors , Cathepsin L/antagonists & inhibitors , Protease Inhibitors/chemical synthesis , Quinazolines/chemical synthesis , Animals , Antineoplastic Agents/pharmacology , Catalytic Domain , Cathepsin B/chemistry , Cathepsin B/isolation & purification , Cathepsin H/chemistry , Cathepsin H/isolation & purification , Cathepsin L/chemistry , Cathepsin L/isolation & purification , Cell Proliferation/drug effects , Cell Survival/drug effects , Drug Design , Goats , Hep G2 Cells , Humans , Kinetics , Liver/chemistry , Liver/enzymology , Microwaves , Molecular Docking Simulation , Protease Inhibitors/pharmacology , Quinazolines/pharmacology , Structure-Activity RelationshipABSTRACT
A direct correlation between cathepsin expression-cancer progression and elevated levels of cathepsins due to an imbalance in cellular inhibitors-cathepsins ratio in inflammatory diseases necessitates the work on the identification of potential inhibitors to cathepsins. In the present work we report the synthesis of some 2,3-dihydroquinazolin-4(1H)-ones followed by their evaluation as cysteine protease inhibitors in general and cathepsin B and cathepsin H inhibitors in particular. 2,3-Dihydroquinazolin-4(1H)-ones, synthesized by the condensation of anthranilamide and carbonyl compound in presence of PPA-SiO2 catalyst, were characterized by spectral analysis. The designed compounds were screened as inhibitors to proteolysis on endogenous protein substrates. Further, a distinct differential pattern of inhibition was obtained for cathepsins B and H. The inhibition was more to cathepsin B with Ki values in nanomolar range. However, cathepsin H was inhibited at micromolar concentration. Maximum inhibition was shown by compounds, 1e and 1f for cathepsin B and compounds 1c and 1f for cathepsin H. The synthesized compounds were established as reversible inhibitors of cathepsins B and H. The results were also compared with the energy of interaction between enzyme active site and compounds using iGemdock software.
