N-substituted acetonitrile inhibitors of cathepsin L

These two applications claim small peptide and benzamide derivatives of acetonitrile, mostly a-substituted, as inhibitors of the Cathepsins. They are shown to be inhibitors of cathepsin L with potencies in the 40 nM range. They are claimed to be useful in treating chronic obstructive pulmonary disease (COPD) and diseases mediated by cathepsin L or cathepsin S.     

Carbamate-based reversible inhibitors of cathepsin S and cathepsin K

The preparation of a series of carbamate derivatives of dipeptide nitriles provides cathepsin inhibitors that, according to the P₃ residue employed, are reported to selectively inhibit cathepsin S or cathepsin K. The resulting inhibitors are claimed to be useful in the treatment of autoimmune diseases or bone diseases, respectively.     

Cysteine protease inhibitors as potential antiparasitic agents

Parasitic cysteine proteases have attracted considerable attention, primarily due to their essential roles in the maintenance of cellular homeostatic processes such as metamorphosis and organogenesis. They also regulate host-parasite interactions by modulating a variety of pathobiological events, including host tissue degradation, nutrient uptake and immune evasion. The specific inhibition of these enzymes, by either immunoprophylaxis or chemotherapy, may potentially impair the survival mechanisms of the parasites. Therefore, these proteases are promising targets for vaccines or chemotherapeutics. To date, a number of cysteine protease inhibitors, including fluoromethyl ketone, heterocyclic oxygen-containing peptidomimetics, or vinyl sulfones, have been introduced and evaluated for protozoan infections. Pioneer studies of parasitic cysteine protease inhibitors have employed irreversible inhibitors. However, recent trends show a use of reversible inhibitors, largely owing to the potential harm of non-selective irreversible inhibitors. Several non-peptide inhibitors that exhibit more drug-like properties have recently been developed, through which protease-mediated degradation can be impeded in living systems. These non-peptide inhibitors also appear to reveal potential for high in vivo activity and selectivity against parasites. This review focuses on the current understanding of the actions and properties of parasitic cysteine proteases and describes advances in the development of specific inhibitors for cysteine proteases, largely based on cathepsins B and L, which may be useful in the development of novel antiparasitic agents.     

Inhibitors of cathepsin C (dipeptidyl peptidase I)

Importance to the field: Cathepsin C (dipeptidyl peptidase I) plays a key role in the activation of several degradative enzymes linked to tissue destruction in inflammatory diseases. Thus, cathepsin C inhibitors could potentially be effective therapeutics for the treatment of such diseases as chronic obstructive pulmonary disease and cystic fibrosis.

Areas covered in this review: Although this article focuses on cathepsin C inhibitor patents, the journal literature concerning small molecule inhibitors of the enzyme is also covered comprehensively (1981 – 2009).

What the reader will gain: It is our aim to give the reader a complete overview of the cathepsin C inhibitor chemotypes that have been disclosed to date. In addition, key biological data have been included for both irreversible and reversible inhibitors.

Take home message: All known cathepsin C inhibitors are believed to have a covalent interaction with the Cys-234 residue of the enzyme. The electrophilic and sometimes peptidic nature of these molecules is associated with poor metabolic stability and is also a potential safety concern. Thus, overcoming developability issues is a serious hurdle for these compounds and there can be little doubt that this is the principal reason why no cathepsin C inhibitors appear to have reached clinical development so far.     

Lysosomotropism of basic cathepsin K inhibitors contributes to increased cellular potencies against off-target cathepsins and reduced functional selectivity

The lysosomal cysteine protease cathepsin K is a target for osteoporosis therapy. The aryl-piperazine-containing cathepsin K inhibitor CRA-013783/L-006235 (1) displays greater than 4000-fold selectivity against the lysosomal/endosomal antitargets cathepsin B, L, and S. However, 1 and other aryl-piperazine-containing analogues, including balicatib (10), are approximately 10-100-fold more potent in cell-based enzyme occupancy assays than against each purified enzyme. This phenomenon arises from their basic, lipophilic nature, which results in lysosomal trapping. Consistent with its lysosomotropic nature, 1 accumulates in cells and in rat tissues of high lysosome content. In contrast, nonbasic aryl-morpholino-containing analogues do not exhibit lysosomotropic properties. Increased off-target activities of basic cathepsin K inhibitors were observed in a cell-based cathepsin S antigen presentation assay. No potency increases of basic inhibitors in a functional cathepsin K bone resorption whole cell assay were detected. Therefore, basic cathepsin K inhibitors, such as 1, suffer from reduced functional selectivities compared to those predicted using purified enzyme assays.     

Recent developments of cathepsin inhibitors and their selectivity

Cathepsins play an important role in the degradation of host connective tissues, the generation of bioactive proteins and antigen processing. They have been implicated in osteoporosis, muscular dystrophy, rheumatoid arthritis, bronchitis, emphysema, viral infection, cancer metastasis and neurodegenerative diseases, such as Alzheimer’s disease and Huntington’s disease. Recently, increased interest in cathepsin inhibitors has been generated with potential therapeutic targets, such as cathepsin K or cathepsin L for osteoporosis and cathepsin S for immune modulation. Of the 53 patents assessed in this review, granted between March 1998 and February 2001, there were 40 patents related to cysteine proteinase inhibitors, 7 related to aspartic proteinase inhibitors and 6 related to serine proteinase inhibitors. Of the 40 patents, 14 disclosed the novel compounds that were more selective against cathepsin K or cathepsin S than cathepsin B and cathepsin L. The compounds, showing experimental evidences, were evaluated and their biological activities in animal models determined. However, only 4 patents presented significant results in vivo. These patents may be a basis for promoting further evaluation and developing second generation cathepsin inhibitors.     

Cathepsin B and L inhibitors: a patent review (2010 - present)

Introduction: Cathepsins play an important role in protein degradation and processing. Aberrant cathepsin B or L is closely associated with many serious diseases such as cancer, osteoporosis and autoimmune disorders. Therefore, development of potent and selective cathepsin B and L inhibitors has aroused much attention in recent years. Although several classes of cathepsin inhibitors are presently available, there are still some problems to solve, such as broad-spectrum inhibition to protease, specially cysteine proteases, which lead to unpredictable side effects in clinical trials. Therefore, it is very necessary to discovery new scaffolds and new application of cathepsin B and L inhibitors for developing therapeutic agents for treating diseases mediated by cathepsin B or L.

Areas covered: This updated review summarizes new patents on cathepsin B and L inhibitors from 2010 to present.

Expert opinion: The review gives the latest development in the area of inhibitors of cathepsin B and L, which have been considered key therapeutic targets for the development of drugs treating related diseases. This review puts emphasis on the discovery of novel small molecule inhibitors of cathepsin B and L, as well as their new application as new therapeutic agents.     

Characterization of P-glycoprotein Mediated Transport of K02, a Novel Vinylsulfone Peptidomimetic Cysteine Protease Inhibitor,Across MDR1-MDCK and Caco-2 Cell Monolayers

Purpose. Here we characterized the transport properties of morpholine-urea-phenylalanine- homophenylalanine-vinylsulfone-phenyl (K02), a newly developed peptidomimetic cysteine protease inhibitor, across monolayers of P-gp-expressed MDR1 transfected MDCK cells (MDR1-MDCK) and Caco-2 cells. Methods. MDR1-MDCK, MDCK and Caco-2 cells, grown to confluence on Transwell insert membranes, were used to investigate transcellular transport of [¹⁴C]-K02. Results. The basolateral to apical (B-A) flux of 10 M [^I4C]-K02 across MDR1-MDCK cells was markedly greater than its apical to basolateral (A-B) flux (ratio = 39). This specific B-A transport was temperature dependent and saturable, with an apparent Michaelis-Menten constant and maximum velocity of 69.1 ± 19.5 M and 148.9 ± 16.3 pmol/min/cm², respectively. This B-A flux was significantly inhibited by cyclosporine (IC₅₀ = 17.1 ± 0.7 M), vinblastine (IC₅₀ = 75.9 ± 13.0 M) and verapamil (IC₅₀ = 236 ± 63 M). In Caco-2 cell monolayers, the B-A flux was reduced about 50% compared to that in MDR1-MDCK and the A-B flux was increased about 8-fold. The apparent Michaelis-Menten constant and maximum velocity values for the B-A transport were 71.8 ± 45.9 M and 35.3 ± 9.0 pmol/min/ cm². This B-A flux was also significantly inhibited by P-gp substrates/ inhibitors. Western blots showed that the P-gp expression in MDR1-MDCK cells was about 10-fold that in Caco-2 cells. Conclusions. K02 is transported by P-gp in both MDR1-MDCK and Caco-2 cells, and the in vitro interactions between K02 and various P-gp substrates may provide strategies to overcome the bioavailability barrier by intestinal P-gp. __     

Synthesis of histidine-containing dipeptide affinity-labelling agents

Peptidyl diazomethyl ketones and fluoromethyl ketones containing histidine in the C-terminal position were synthesized to determine their properties as proteinase inactivators. These were examined chiefly with derivatives of Z-Ala-His. The protection of histidine during conversion of the C-terminal residue to the diazomethyl ketone required unblocking conditions which avoid acid due to the lability of this function. This was achievable with a Cbz-imidazole derivative since aminolysis provided deblocking without disturbance of the diazomethyl ketone function. In the case of the fluoromethyl ketone synthesis using fluoroacetic anhydride (Dakin-West procedure), the desired product could be isolated without ring blocking. The Z-Ala-His products showed enhanced selectivity for inactivation of cathepsin B over L when compared to analogous dipeptide inhibitors.     

Cathepsin K as a target for the treatment of osteoporosis

Cathepsin K is a recently discovered member of the papain superfamily of cysteine proteinases. This enzyme is highly expressed in human osteoclast cells where it plays an important role in the resorption processes in normal bone remodelling. The importance of cathepsin K in osteoclast-mediated resorption of the bone matrix provides a rationale for the design of inhibitors of cathepsin K as potential drugs for the treatment of diseases of excess bone remodelling such as osteoporosis. Successful application of modern methods of drug discovery, including genomics and structure-based methods of drug design, has resulted in the identification of this previously unknown therapeutic target and the rapid elucidation of novel, potent and selective inhibitors of human osteoclast cathepsin K. Several classes of inhibitors of cathepsin K that have been reported in the published literature and in recent patent filings are described in this review.     

Cathepsin K inhibitors for osteoporosis and potential off-target effects

Cathepsin K is a highly potent collagenase and the predominant papain-like cysteine protease expressed in osteoclasts. Cathepsin K deficiencies in humans and mice have underlined the central role of this protease in bone resorption and, thus, have rendered the enzyme as an attractive target for anti-resorptive osteoporosis therapy. In the past decade, a lot of efforts have been made in developing highly potent, selective and orally applicable cathepsin K inhibitors. Some of these inhibitors have passed preclinical studies and are presently in clinical trials at different stages of advancement. The development of the inhibitors and preliminary results of the clinical trials revealed problems and lessons concerning the in situ specificity of the compounds and their tissue targeting. In this review, we briefly summarize the history of cathepsin K research and discuss the current development of cathepsin K inhibitors as novel anti-resorptives for the treatment of osteoporosis. We also discuss potential off-target effects of cathepsin K inhibition and alternative applications of cathepsin K inhibitors in arthritis, atherosclerosis, blood pressure regulation, obesity and cancer.     

组织蛋白酶B与胃癌研究进展

组织蛋白酶B是细胞溶酶体内的一种半胱氨酸蛋白酶,其可分布于肿瘤细胞的胞浆内,可降解层连蛋白、纤连蛋白、Ⅳ型胶原等细胞外基质成分,并可促进肿瘤血管的形成,是恶性肿瘤侵袭转移的关键酶之一。组织蛋白酶抑B制剂CA-074Me等能有效抑制组织蛋白酶B的作用,有望成为胃癌治疗的新的靶点,对改善预后,延长生存期可能有帮助。     

Novel protease and polymerase inhibitors for the treatment of hepatitis C virus infection

Chronic hepatitis C virus (HCV) infection remains a global health concern with nearly 200 million carriers worldwide. Present treatment consists of the use of pegylated interferon plus the purine analogue ribavirin. Serious side effects and the fact that an overall 40 – 50% of patients do not accomplish sustained virological response with the present treatment warrant the need for novel anti-HCV therapies. The HCV serine protease and the RNA-dependent RNA polymerase have shown to be excellent targets for selective antiviral therapy. Early clinical studies have resulted in encouraging results. However, and not unexpectedly, preclinical evidence suggests that the virus may become rapidly resistant to such inhibitors. Therefore, combination therapy of drugs with different mode of action and resistance profiles may be required. This review focuses on the present status of these two families of HCV inhibitors that are in development.     

Novel cruzain inhibitors for the treatment of Chagas' disease

The protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas' disease, affects millions of individuals and continues to be an important global health concern. The poor efficacy and unfavorable side effects of current treatments necessitate novel therapeutics. Cruzain, the major cysteine protease of T. cruzi, is one potential novel target. Recent advances in a class of vinyl sulfone inhibitors are encouraging; however, as most potential therapeutics fail in clinical trials and both disease progression and resistance call for combination therapy with several drugs, the identification of additional classes of inhibitory molecules is essential. Using an exhaustive virtual-screening and experimental validation approach, we identify several additional small-molecule cruzain inhibitors. Further optimization of these chemical scaffolds could lead to the development of novel drugs useful in the treatment of Chagas' disease.     

Novel 16-substituted bifunctional derivatives of huperzine B： multifunctional cholinesterase inhibitors

Aim： To design novel bifunctional derivatives of huperzine B （HupB） based on the concept of dual binding site of acetylcholinesterase （ACHE） and evaluate their pharmacological activities for seeking new drug candidates against Alzheimer＇s disease （AD）. Methods： Novel 16-substituted bifunctional derivatives of HupB were synthesized through chemical reactions. The inhibitory activities of the derivatives toward AChE and butyrylcholinesterase （BuChE） were determined in vitro by modified EIIman＇s method. Cell viability was quantified by the reduction of MTT. Results： A new preparative method was developed for the generation of 16-substituted derivatives of HupB, and pharmacological trials indicated that the derivatives were multifunctional cholinesterase inhibitors targeting both AChE and BuChE. Among the derivatives tested, 9c, 9e, 9f, and 9i were 480 to 1360 times more potent as AChE inhibitors and 370 to 1560 times more potent as BuChE inhibitors than the parent HupB. Further preliminary pharmacological trials of derivatives 9c and 9i were performed, including examining the mechanism of AChE inhibition, the substrate kinetics of the enzyme inhibition, and protection against hydrogen peroxide （H2O2）-induced cytotoxicity in PC12 cells. Conclusion： Preliminary pharmacological evaluation indicated that 16-substituted derivatives of HupB, particularly 9c and 9i, would be potentially valuable new drug candidates for AD therapy, and further exploration is needed to evaluate their pharmacological and clini- cal efficacies.     

Serum and urine bone resorption markers and pharmacokinetics of the cathepsin K inhibitor ONO-5334 after ascending single doses in post menopausal women

Historically, much drug discovery and development in psychopharmacology tended to be empirical. However, over the last 20 years it has primarily been target oriented, with synthesis and selection of compounds designed to act at a specific neurochemical site. Such compounds are then examined in functional animal models of disease. There is little evidence that this approach (which we call 'targetophilia') has enhanced the discovery process and some indications that it may have retarded it. A major problem is the weakness of many animal models in mimicking the disease and the lack of appropriate biochemical markers of drug action in animals and patients. In this review we argue that preclinical studies should be conducted as if they were clinical studies in design, analysis, and reporting, and that clinical pharmacologists should be involved at the earliest stages, to help ensure that animal models reflect as closely as possible the clinical disease. In addition, their familiarity with pharmacokinetic-pharmacodynamic integration (PK-PD) would help ensure that appropriate dosing and drug measurement techniques are applied to the discovery process, thereby producing results with relevance to therapeutics. Better integration of experimental and clinical pharmacologists early in the discovery process would allow observations in animals and patients to be quickly exchanged between the two disciplines. This non-linear approach to discovery used to be the way research proceeded, and it resulted in productivity that has never been bettered. It also follows that occasionally 'look-see' studies, a proven technique for drug discovery, deserve to be reintroduced.     

Approved and emerging PI3K inhibitors for the treatment of chronic lymphocytic leukemia and non-Hodgkin lymphoma

ABSTRACT

Introduction

PI3K inhibition with idelalisib (at that time CAL-101) was at the forefront of the development of molecularly targeted therapies in Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Leukemia (SLL) and follicular lymphoma. However, after initial approval, subsequent trials identified specific immune-mediated and infectious toxicity that led to a reduced use and stopped the further development of this agent. PI3K inhibition as a treatment paradigm fell out of favor compared to other developments such as BTK or BCL2 inhibitors.     

The effect of monoamine oxidase A and B inhibitors on rat serum prolactin

Serum prolactin levels were assayed in rats treated with specific inhibitors of monoamine oxidase (MAO) A or B. Monoamine oxidase A was inhibited by MD780515, clorgyline and Lilly 51641, and MAO B by pargyline and deprenyl (all at 10 mg/kg, p.o.). Serum prolactin levels were significantly reduced 1 hour after treatment with MAO A inhibitors, but were unaltered by MAO B inhibitors. The time-course of the reduction in serum prolactin did not correspond to that of MAO A inhibition. When rats were treated with clorgyline, serum prolactin returned to control values by 6 hr after treatment, whereas MAO A was inhibited by 92–94% over the whole period. At a time when MAO A inhibitors produced no change in serum prolactin (5 hr after treatment) they abolished the rise in serum prolactin induced by reserpine (5 mg/kg, i.p.), indicating a continuing absence of MAO A activity in the neurones regulating prolactin release. Monoamine oxidase B inhibitors did not alter the effect of reserpine on serum prolactin. Possible reasons for the rapid recovery of serum prolactin levels are discussed.     

海滩马鞭草(Verbena littoralis H.B.K.)的组织构造显微鉴别

目的首次对海滩马鞭草的组织构造和显微特征进行鉴别。方法取干燥海滩马鞭草的茎、根茎、叶制成横切面永久切片 ,将全草粉末用水合氯醛透化、将根茎用铬酸 硝酸解离后 ,置光学显微镜下观察。结果绘制出海滩马鞭草的根茎、茎和叶的组织构造详图和全草粉末的显微特征详图。结论为鉴别海滩马鞭草药材提供科学的依据。     

Ligand-based virtual screening and molecular docking studies to identify the critical chemical features of potent cathepsin D inhibitors

Cathepsin D is a major component of lysosomes and plays a major role in catabolism and degenerative diseases. The quantitative structure-activity relationship study was used to explore the critical chemical features of cathepsin D inhibitors. Top 10 hypotheses were built based on 36 known cathepsin D inhibitors using HypoGen/Discovery Studio v2.5. The best hypothesis Hypo1 consists of three hydrophobic, one hydrogen bond acceptor lipid, and one hydrogen bond acceptor features. The selected Hypo1 model was cross-validated using Fischer's randomization method to identify the strong correlation between experimental and predicted activity value as well as the test set and decoy sets used to validate its predictability. Moreover, the best hypothesis was used as a 3D query in virtual screening of Scaffold database. Subsequently, the screened hit molecules were filtered by applying Lipinski's rule of five, absorption, distribution, metabolism, and toxicity, and molecular docking studies. Finally, 49 compounds were obtained as potent cathepsin D inhibitors based on the consensus scoring values, critical interactions with protein active site residues, and predicted activity values. Thus, we suggest that the application of Hypo1 could assist in the selection of potent cathepsin D leads from various databases. Hence, this model was used as a valuable tool to design new candidate for cathepsin D inhibitors.