Study on enhanced serum protein protecting and anti-cathepsin activities of various curcumin formulations containing traditional excipients and bio-enhancers.

Cathepsins have emerged out as significant targets in variety of tissue degenerative disorders such as inflammation, alzeimers, tumerogenesis including metastasis and invasion. Elevated levels of cathepsins and reduced cellular inhibitors at the site of these diseased conditions suggest the exploration of novel inhibitors of cathepsins. In the search of effective novel inhibitors as anti-cathepsin agents different natural products are also screened. One such molecule, curcumin has been reported as potential anti-cathepsin agent in recent past. Low solubility of curcumin makes it an important subject for screening effect of different pharmaceutical excipients toward enhanced solubility. In the present work we report serum protein protecting and anti-cathepsin activities of 28 different formulations of curcumin. The formulations have been prepared using four ingredients used in traditional medicinal system. Milk has been found to enhance solubility to a significant level. Cow milk fat, sucrose and piperine exhibited positive cooperation. The results have been explained on the basis of chemical behavior of different ingredients.

Some thiocarbamoyl based novel anticathepsin agents.

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.

Effects of Five Substances with Different Modes of Action on Cathepsin H, C and L Activities in Zebrafish Embryos.

Cathepsins have been proposed as biomarkers of chemical exposure in the zebrafish embryo model but it is unclear whether they can also be used to detect sublethal stress. The present study evaluates three cathepsin types as candidate biomarkers in zebrafish embryos. In addition to other functions, cathepsins are also involved in yolk lysosomal processes for the internal nutrition of embryos of oviparous animals until external feeding starts. The baseline enzyme activity of cathepsin types H, C and L during the embryonic development of zebrafish in the first 96 h post fertilisation was studied. Secondly, the effect of leupeptin, a known cathepsin inhibitor, and four embryotoxic xenobiotic compounds with different modes of action (phenanthrene-baseline toxicity; rotenone-an inhibitor of electron transport chain in mitochondria; DNOC (Dinitro-ortho-cresol)-an inhibitor of ATP synthesis; and tebuconazole-a sterol biosynthesis inhibitor) on in vivo cathepsin H, C and L total activities have been tested. The positive control leupeptin showed effects on cathepsin L at a 20-fold lower concentration compared to the respective LC50 (0.4 mM) of the zebrafish embryo assay (FET). The observed effects on the enzyme activity of the four other xenobiotics were not or just slightly more sensitive (factor of 1.5 to 3), but the differences did not reach statistical significance. Results of this study indicate that the analysed cathepsins are not susceptible to toxins other than the known peptide-like inhibitors. However, specific cathepsin inhibitors might be identified using the zebrafish embryo.

Increased cystatin F levels correlate with decreased cytotoxicity of cytotoxic T cells.

Background Cystatin F is a protein inhibitor of cysteine peptidases, expressed predominantly in immune cells and localised in endosomal/lysosomal compartments. In cytotoxic immune cells cystatin F inhibits both the major pro-granzyme convertases, cathepsins C and H that activate granzymes, and cathepsin L, that acts as perforin activator. Since perforin and granzymes are crucial molecules for target cell killing by cytotoxic lymphocytes, defects in the activation of either granzymes or perforin can affect their cytotoxic potential. Materials and methods Levels of cystatin F were assessed by western blot and interactions of cystatin F with cathepsins C, H and L were analysed by immunoprecipitation and confocal microscopy. In TALL-104 cells specific activities of the cathepsins and granzyme B were determined using peptide substrates. Results Two models of reduced T cell cytotoxicity of TALL-104 cell line were established, either by treatment by ionomycin or by immunosuppressive transforming growth factor beta. Reduced cytotoxicity correlated with increased levels of cystatin F and with attenuated activities of cathepsins C, H and L and of granzyme B. Co-localisation of cystatin F and cathepsins C, H and L and interactions between cystatin F and cathepsins C and H were demonstrated. Conclusions Cystatin F is designated as a possible regulator of T cell cytotoxicity, similar to its role in natural killer cells.

SAR studies of some acetophenone phenylhydrazone based pyrazole derivatives as anticathepsin agents.

Cathepsins have emerged as promising molecular targets in a number of diseases such as Alzeimer's, inflammation and cancer. Elevated cathepsin's levels and decreased cellular inhibitor concentrations have emphasized the search for novel inhibitors of cathepsins. The present work is focused on the design and synthesis of some acetophenone phenylhydrazone based pyrazole derivatives as novel non peptidyl inhibitors of cathepsins B, H and L. The synthesized compounds after characterization have been explored for their inhibitory potency against cathepsins B, H and L. The results show that some of the synthesized compounds exhibit anti-catheptic activity with Ki value of the order of 10-10M. Differential inhibitory effects have been observed for cathepsins B, H and L. Cathepsin L is inhibited more pronounced than cathepsin B and cathepsin H in that order.

Quinazoline derivatives as cathepsins B, H and L inhibitors and cell proliferating agents.

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.

2,5-Diaryloxadiazoles and their precursors as novel inhibitors of cathepsins B, H and L.

High levels of cathepsins indicated in various pathological conditions like arthritis, cancer progressions, and atherosclerosis explains the need to explore potential inhibitors of these proteases which can be of great therapeutic significance. We, in the present work, report the synthesis of some 2,5-diaryloxadiazoles from N-subsitutedbenzylidenebenzohydrazides. The synthesized compounds were screened for their inhibitory potential on cathepsins B, H and L. Structure Activity Relationship studies show that 2,5-diaryloxadiazoles were less inhibitory than their precursors. 1i and 2k have been found to be most inhibitory to cathepsins B and L. Their Ki values have been calculated as 11.38×10(-8)M and 66.4×10(-8)M for cathepsin B and 4.2×10(-9)M and 47.31×10(-9)M for cathepsin L, respectively. However, cathepsin H activity was maximally inhibited by compounds, 1e and 2c with Ki values of 4.4×10(-7)M and 5.6×10(-7)M, respectively. Enzyme kinetic studies suggest that these compounds are competitive inhibitors to the enzymes. The results have been compared with docking results obtained using iGemDock.

2,3-Dihydroquinazolin-4(1H)-one derivatives as potential non-peptidyl inhibitors of cathepsins B and H.

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.

N-formylpyrazolines and N-benzoylpyrazolines as novel inhibitors of mammalian cathepsin B and cathepsin H.

Cathepsins, intracellular proteases, are known to be involved in a number of physiological processes ranging from degradation of extracellular proteins, prohormone processing, progressions of atherosclerosis, etc. High levels of cathepsins have been indicated in various pathological conditions like arthritis, cancer and other tissue degenerative disorders. One of the reasons attributed to these high levels is decrease in inhibitor concentration. Therefore, the work on the identification of small molecular weight compounds as inhibitors of cysteine proteases is of great therapeutic significance. Exploring this work in the same direction, we here present the synthesis of substituted N-formylpyrazolines and N-benzoylpyrazolines and study these as inhibitors to cysteine proteases. After a preliminary screening of the compounds as inhibitors to cysteine proteases in general, studies were carried out to study their inhibitory effects on cathepsin B and cathepsin H. SAR studies show that N-formylpyrazolines were better inhibitors than N-benzoylpyrazolines. The most potent inhibitors among the two series were nitro substituted compounds 1i and 2i with Ki values of ∼1.1×10(-9)M and 19.5×10(-8)M for cathepsin B and Ki values of ∼5.19×10(-8)M and 9.8×10(-7)M for cathepsin H, respectively. Docking experiments showing interaction between N-formylpyrazolines and N-benzoylpyrazolines with enzyme active sites structures also provided useful insights.

SAR studies of differently functionalized chalcones based hydrazones and their cyclized derivatives as inhibitors of mammalian cathepsin B and cathepsin H.

Cathepsins have emerged as potential drug targets for melanoma therapy and engrossed attention of researchers for development and evaluation of cysteine cathepsin inhibitors as cancer therapeutics. In this direction, we have designed, synthesized, and assayed in vitro a small library of 30 low molecular weight functionalized analogs of chalcone hydrazones for evaluating structure-activity relationship aspects and inhibitory potency against cathepsin B and H. The maximum inhibitory effect was exerted by chalcone hydrazones, which are open chain analogues followed by their cyclized derivatives, pyrazolines and pyrazoles. All the synthesized compounds were established as reversible inhibitors of these enzymes. Cathepsin B was selectively inhibited by the compounds in each series. Compounds 1d, 2d and 4d were recognized as most potent inhibitors of cathepsin B in this study with Ki values of 0.042 µM, 0.053 µM and 0.131 µM whereas 1b (Ki=1.111 µM), 2b (Ki=1.174 µM) and 4b (Ki=1.562 µM) inhibited cathepsin H activity effectively. And, preeminent cathepsin B inhibitors were -NO2 functionalized however, -Cl substituted moieties were the most persuasive inhibitors for cathepsin H among all the designed compounds. Molecular docking studies performed using iGemdock provided valuable insights.

SAR studies of o-hydroxychalcones and their cyclized analogs and study them as novel inhibitors of cathepsin B and cathepsin H.

Cathepsins have emerged as a potential target for anti-cancer drug development. In the present study, we have synthesized three structurally related series of flavanoids i.e., 2'-hydroxychalcones, flavanones and flavones and assayed in vitro to study their inhibitory potency against cathepsin B and H, promising drug candidate for cancer therapy. Enzyme kinetics studies were carried out in presence of these compounds after preliminary proteolytic studies on endogenous protein substrates. SAR studies suggested that open chain flavanoids were better inhibitors as compared to their cyclized analogs. The most potent inhibitors among the three series were nitro substituted compounds 1g, 2g and 3g with Ki values of ∼6.18×10(-8) M, 4.8×10(-7) M and 7.85×10(-7) M for cathepsin B and Ki values of ∼2.8×10(-7) M, 31.8×10(-6) M and 33.7×10(-6) M for cathepsin H, respectively. The relationship between chalcone, flavanones and flavone structures interpreted by docking studies on cathepsin B and H also provided useful insights.

Acyl hydrazides and triazoles as novel inhibitors of mammalian cathepsin B and cathepsin H.

In the past decade, the work on the identification of small molecular weight compounds as inhibitors of cysteine proteases has been in focus. In this direction, we here present the facile microwave assisted synthesis of some acyl hydrazides and triazoles, followed by their evaluation as protease inhibitors and inhibitory studies on cathepsin B and cathepsin H, two significant lysosomal cysteine proteases. The compounds were characterized by (1)H NMR, (13)C NMR, Mass and IR spectral data. The compounds which were found inhibitory to endogenous proteolysis in liver homogenate at pH 5.0 were further studied for determination of inhibition type and Ki values on purified cathepsin B and cathepsin H. The maximum inhibitory effect was exerted by 3-(3'-nitrophenyl)-5-(3'-nitrophenyl)-4-amino-1,2,4-triazoles (2c), 3-(4'-chlorophenyl)-5-(4'-chloro phenyl)-4-amino-1,2,4-triazoles (2h), 3-(3'-aminophenyl)-5-(3'-aminophenyl)-4-amino-1,2,4-triazoles (2i) and 4-methoxybenzohydrazide (1b).

Design, synthesis and docking studies of bischalcones based quinazoline-2(1H)-ones and quinazoline-2(1H)-thiones derivatives as novel inhibitors of cathepsin B and cathepsin H.

A direct correlation between cancer progression and cathepsin expression has engrossed extensive consideration of these enzymes as potential drug targets for anticancer therapies. The present work is emphasized on potential therapeutic impact of 27 compounds on cathepsin B and cathepsin H, two significant lysosomal cysteine cathepsins involved in tumor progression and invasion. Bischalcones and their quinazoline-2(1H)-one and quinazoline-2(1H)-thione derivatives have been evaluated as potent inhibitors of cathepsin B and cathepsin H. Results exposed that bischalcones and their quinazoline-2(1H)-thione derivative inhibited cathepsin B and cathepsin H in a competitive manner whereas both cathepsins were inhibited in a non-competitive manner by quinazoline-2(1H)-one derivative. The experimental studies were compared with in silico docking results conducted with the help of iGemdock. The compounds under investigation add to the existing knowledge of non-peptidyl inhibitors of cathepsins B and H for anticancer drug development and chemotherapy.