Design, synthesis, and biological evaluation of phenyl thiazole-based AR-V7 degraders.

Multiple Splice variants of AR have been reported in the past few years. These splice variants are upregulated in most cases of CRPC resulting in poor prognosis. Most of these variants lack the ligand binding domain (LBD) but still bind to DNA resulting in constitutive activation of downstream targets. The AR-V7 splice variant has been characterized extensively and current clinical trials in CRPC are exploring the use of AR-V7 as a biomarker. New therapeutic molecules that selectively target AR-V7 are also being explored. However, there is a dearth of information available on the selectivity, phenotypic responses in AR-V7 dependent cell lines and pharmacokinetic properties of such molecules. Using our proprietary computational algorithms and rational SAR optimization, we have developed a potent and selective AR-V7 degrader from a known AR DNA binding domain (DBD) binder. This molecule effectively degraded AR-V7 in a CRPC cell line and demonstrated good oral bioavailability in mouse PK studies. This tool compound can be used to evaluate the pharmacological effects of AR-V7 degraders. Further exploration of SAR can be pursued to develop more optimized lead compounds.

Structural and binding studies of cyclin-dependent kinase 2 with NU6140 inhibitor.

Cyclin-dependent kinase 2 (CDK2) is an established target protein for therapeutic intervention in various diseases, including cancer. Reported inhibitors of CDK2 target the ATP-binding pocket to inhibit the kinase activity. Many small molecule CDK2 inhibitors have been discovered, and their crystal structure with CDK2 or CDK2-cyclin A complex has been published. NU6140 is a CDK2 inhibitor with moderate potency and selectivity. Herein, we report the cocrystal structure determination of NU6140 in complex with CDK2 and confirmation of the binding using various biophysical methods. Our data show that NU6140 binds to CDK2 with a Kd of 800 nM as determined by SPR and stabilizes the protein against thermal denaturation (ΔTm -5°C). The cocrystal structure determined in our study shows that NU6140 binds in the ATP-binding pocket as expected for this class of compounds and interacts with Leu83 and Glu81 with regular hydrogen bonds and with Asp145 via water-mediated H-bond. Based on these data, we propose structural modifications of NU6140 to introduce new interactions with CDK2 that can improve its potency while retaining the selectivity.

Plasmodium chitinases: revisiting a target of transmission-blockade against malaria.

Malaria is a life-threatening disease caused by one of the five species of Plasmodium, among which Plasmodium falciparum cause the deadliest form of the disease. Plasmodium species are dependent on a vertebrate host and a blood-sucking insect vector to complete their life cycle. Plasmodium chitinases belonging to the GH18 family are secreted inside the mosquito midgut, during the ookinete stage of the parasite. Chitinases mediate the penetration of parasite through the peritrophic membrane, facilitating access to the gut epithelial layer. In this review, we describe Plasmodium chitinases with special emphasis on chitinases from P. falciparum and P. vivax, the representative examples of the short and long forms of this protein. In addition to the chitinase domain, chitinases belonging to the long form contain a pro-domain and chitin-binding domain. Amino acid sequence alignment of long and short form chitinase domains reveals multiple positions containing variant residues. A subset of these positions was found to be conserved or invariant within long or short forms, indicating the role of these positions in attributing form-specific activity. The reported differences in affinities to allosamidin for P. vivax and P. falciparum were predicted to be due to different residues at two amino acid positions, resulting in altered interactions with the inhibitor. Understanding the role of these amino acids in Plasmodium chitinases will help us elucidate the mechanism of catalysis and the mode of inhibition, which will be the key for identification of potent inhibitors or antibodies demonstrating transmission-blocking activity.

Discovery of CA-4948, an Orally Bioavailable IRAK4 Inhibitor for Treatment of Hematologic Malignancies.

Small molecule potent IRAK4 inhibitors from a novel bicyclic heterocycle class were designed and synthesized based on hits identified from Aurigene's compound library. The advanced lead compound, CA-4948, demonstrated good cellular activity in ABC DLBCL and AML cell lines. Inhibition of TLR signaling leading to decreased IL-6 levels was also observed in whole blood assays. CA-4948 demonstrated moderate to high selectivity in a panel of 329 kinases as well as exhibited desirable ADME and PK profiles including good oral bioavailability in mice, rat, and dog and showed >90% tumor growth inhibition in relevant tumor models with excellent correlation with in vivo PD modulation. CA-4948 was well tolerated in toxicity studies in both mouse and dog at efficacious exposure. The overall profile of CA-4948 prompted us to select it as a clinical candidate for evaluation in patients with relapsed or refractory hematologic malignancies including non-Hodgkin lymphoma and acute myeloid leukemia.

Structure of cyclin-dependent kinase 2 (CDK2) in complex with the specific and potent inhibitor CVT-313.

CVT-313 is a potent CDK2 inhibitor that was identified by screening a purine-analogue library and is currently in preclinical studies. Since this molecule has the potential to be developed as a CDK2 inhibitor for cancer therapy, the potency of CVT-313 to bind and stabilize CDK2 was evaluated, together with its ability to inhibit aberrant cell proliferation. CVT-313 increased the melting temperature of CDK2 by 7°C in thermal stabilization studies, thus indicating its protein-stabilizing effect. CVT-313 inhibited the growth of human lung carcinoma cell line A549 in a dose-dependent manner, with an IC50 of 1.2 µM, which is in line with the reported biochemical potency of 0.5 µM. To support the further chemical modification of CVT-313 and to improve its biochemical and cellular potency, a crystal structure was elucidated in order to understand the molecular interaction of CVT-313 and CDK2. The crystal structure of CDK2 bound to CVT-313 was determined to a resolution of 1.74 Šand clearly demonstrated that CVT-313 binds in the ATP-binding pocket, interacting with Leu83, Asp86 and Asp145 directly, and the binding was further stabilized by a water-mediated interaction with Asn132. Based on the crystal structure, further modifications of CVT-313 are proposed to provide additional interactions with CDK2 in the active site, which may significantly increase the biochemical and cellular potency of CVT-313.

Design, synthesis and pharmacological screening of novel nitric oxide donors containing 1,5-diarylpyrazolin-3-one as nontoxic NSAIDs.

Various substituted 1,5-diarylpyrazol-3-one derivatives were synthesized and screened for analgesic, anti-inflammatory activities, ulcerogenic potential and for their ability to release nitric oxide. Most compounds exhibited significant analgesic and anti-inflammatory activities. It was interesting to note that out of ten compounds, 7j (59.64%) was found to have anti-inflammatory activity greater than the standard drug Indomethacin (57.89%), whereas compound 7b (57.89%) was found to be equipotent to that of standard, Indomethacin. The pharmacological studies suggested that the presence of 4-nitro and 2-methoxy on phenyl ring at C(5) of pyrazole has a significant anti-inflammatory activity and 4-chloro substitution on same phenyl ring was found to have decreased activity. However only a phenyl substituted derivative was found to have most potent activity. Compound 7j containing plane phenyl at C(5) of pyrazole was found to have significant analgesic activity (56.86%) in acetic acid induced writhing model. Compounds 7d and 7i having 4-chloro substituted phenyl ring showed least analgesic activity (10.78%) and (6.86%) respectively. The compounds also showed significantly reduced GI-ulcerogenicity and gastroprotective results in histopathological studies i.e. they were found to be causing no mucosal injury. All the synthesized compounds were found to exhibit significant nitric oxide releasing activity, in both in vitro and in vivo models. Molecular docking studies served to be an important tool for the study of binding of compounds with that of a COX-2 enzyme. The results of the docking studies were found to endorse the result of experimental work. Thus, the rationale used to design the NCEs was found to produce the promising results as anticipated. Therefore it can be said that the strategy employed can serve as an important tool in future for the design and development of novel therapeutic agents of various categories too.

Novel 4-(morpholin-4-yl)-N'-(arylidene)benzohydrazides: synthesis, antimycobacterial activity and QSAR investigations.

A series of 4-(morpholin-4-yl)-N'-(arylidene)benzohydrazides were synthesized using appropriate synthetic route. Antimycobacterial activity of the synthesized compounds (5a-5j) was carried out and percentage reduction in relative light units (RLU) was calculated using luciferase reporter phages (LRP) assay. Percentage reduction in relative light units (RLU) for isoniazid was also calculated. The test compounds showed significant antitubercular activity against Mycobacterium tuberculosis H37Rv and clinical isolates: S, H, R, and E resistant M. tuberculosis, when tested in vitro. Quantitative structure-activity relationship (QSAR) investigation with 2D-QSAR analysis was applied to find a correlation between different experimental or calculated physicochemical parameters of the compounds studied and 3D-QSAR analysis and to indicate the exact steric and electronic requirements in the ranges at various positions around pharmacophore. In general Schiff bases exhibit antimycobacterial activity and morpholine ring is important for antimicrobial activity. So we have synthesized 10 different 4-(morpholin-4-yl)-N'-(arylidene)benzohydrazides. The structures of new compounds were characterized by TLC, FTIR, (1)H NMR, mass spectral data and elemental analysis. Amongst the compounds tested 5d and 5c were found to be the most potent, while 5i, 5e, and 5j were found to have an average activity against M. tuberculosis H37Rv and 5a, 5f, 5h, 5g, and 5b were found to have a greater activity against clinical isolates: S, H, R, and E resistant M. tuberculosis as compared to M. tuberculosis H37Rv.

Design, synthesis and pharmacological screening of novel antihypertensive agents using hybrid approach.

Eight derivatives of general formula 2-(2-(4-(3-((5-substituted methylene)-4-oxo-2-(phenylimino)thiazolidin-3-yl)-2-hydroxypropylamino)benzoyl)hydrazinyl)-2-oxoethyl nitrate were synthesized and tested for electrocardiographic, antiarrhythmic, vasorelaxing and antihypertensive activity as well as for in-vitro nitric oxide (NO) releasing ability. Compound 8b 2-(2-(4-(3-(5-benzyliden-4-oxo-2-(phenylimino)thiazolidin-3-yl)-2-hydroxypropylamino)benzoyl)hydrazinyl)-2-oxoethyl nitrate, was the most potent in this series. The pharmacological results suggested that the antiarrhythmic effects of these compounds were related to their adrenolytic properties which are believed to be due to the presence of the 5-(substituted)methylen-2-(phenylimino)thiazolidin-4-one moiety with less bulky, electron donating substituent on the phenyl ring at 5th position of the thiazolidin-4-one. In conclusion, most of the synthesized compounds were significantly potent as antiarrhythmic and antihypertensive; this might be due to the presence of different pharmacopores which might act at different locations with different mode of action. Further insights of the same can be obtained by doing investigation at receptor level. The potency of compounds 8a-8h were promising enough to continue further experiments.