Publications by authors named "Suchitra Ravula"

7 Publications

  • Page 1 of 1

Lead Optimization of 5-Aryl Benzimidazolone- and Oxindole-Based AMPA Receptor Modulators Selective for TARP γ-8.

ACS Med Chem Lett 2018 Aug 13;9(8):821-826. Epub 2018 Jul 13.

Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121, United States.

Glutamate mediates fast excitatory neurotransmission via ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. The trafficking and gating properties of AMPA receptors (AMPARs) can be amplified by transmembrane AMPAR regulatory proteins (TARPs), which are often expressed in localized brain regions. Herein, we describe the discovery, lead optimization, and preclinical characterization of 5-arylbenzimidazolone and oxindole-based negative modulators of AMPARs associated with TARP γ-8, the primary TARP found in hippocampus. High-throughput screen lead was optimized for potency and brain penetration to provide benzimidazolone , JNJ-55511118.1 Replacement of the benzimidazolone core in with an oxindole mitigated reactive metabolite formation and led to the identification of (GluA1/γ-8 pIC = 9.7). Following oral dosing in rats, demonstrated robust target engagement in hippocampus as assessed by autoradiography (ED = 0.6 mg/kg, plasma EC = 9 ng/mL).
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http://dx.doi.org/10.1021/acsmedchemlett.8b00215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6088354PMC
August 2018

Discovery and Characterization of AMPA Receptor Modulators Selective for TARP-γ8.

J Pharmacol Exp Ther 2016 May 17;357(2):394-414. Epub 2016 Mar 17.

Janssen Research and Development, LLC, Neuroscience Therapeutic Area, San Diego, California (M.P.M., N.W., S.R., M.K.A., B.M.S., C.L., B.L., R.M.W., J.A.M., C.D., S.Y., A.D.W., N.I.C., T.W.L.); and Janssen Research and Development, a Division of Janssen Pharmaceutica NV, Neuroscience Therapeutic Area, Beerse, Belgium (L.V.D., T.S.).

Members of the α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid (AMPA) subtype of ionotropic glutamate receptors mediate the majority of fast synaptic transmission within the mammalian brain and spinal cord, representing attractive targets for therapeutic intervention. Here, we describe novel AMPA receptor modulators that require the presence of the accessory protein CACNG8, also known as transmembrane AMPA receptor regulatory protein γ8 (TARP-γ8). Using calcium flux, radioligand binding, and electrophysiological assays of wild-type and mutant forms of TARP-γ8, we demonstrate that these compounds possess a novel mechanism of action consistent with a partial disruption of the interaction between the TARP and the pore-forming subunit of the channel. One of the molecules, 5-[2-chloro-6-(trifluoromethoxy)phenyl]-1,3-dihydrobenzimidazol-2-one (JNJ-55511118), had excellent pharmacokinetic properties and achieved high receptor occupancy following oral administration. This molecule showed strong, dose-dependent inhibition of neurotransmission within the hippocampus, and a strong anticonvulsant effect. At high levels of receptor occupancy in rodent in vivo models, JNJ-55511118 showed a strong reduction in certain bands on electroencephalogram, transient hyperlocomotion, no motor impairment on rotarod, and a mild impairment in learning and memory. JNJ-55511118 is a novel tool for reversible AMPA receptor inhibition, particularly within the hippocampus, with potential therapeutic utility as an anticonvulsant or neuroprotectant. The existence of a molecule with this mechanism of action demonstrates the possibility of pharmacological targeting of accessory proteins, increasing the potential number of druggable targets.
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http://dx.doi.org/10.1124/jpet.115.231712DOI Listing
May 2016

Preclinical characterization of substituted 6,7-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-8(5H)-one P2X7 receptor antagonists.

Bioorg Med Chem Lett 2016 Jan 17;26(2):257-261. Epub 2015 Dec 17.

Janssen Pharmaceutical Research & Development L.L.C., 3210 Merryfield Row, San Diego, CA 92121, United States.

The synthesis, SAR, and preclinical characterization of a series of substituted 6,7-dihydro[1,2,4]triazolo[4,3]pyrazin-8(5H)-one P2X7 receptor antagonists are described. Optimized leads from this series comprise some of the most potent human P2X7R antagonists reported to date (IC50s<1nM). They also exhibit sufficient potency and oral bioavailability in rat to enable extensive in vivo profiling. Although many of the disclosed compounds are peripherally restricted, compound 11d is brain penetrant and upon oral administration demonstrated dose-dependent target engagement in rat hippocampus as determined by ex vivo receptor occupancy with radiotracer 5 (ED50=0.8mg/kg).
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http://dx.doi.org/10.1016/j.bmcl.2015.12.052DOI Listing
January 2016

Discovery of CX-6258. A Potent, Selective, and Orally Efficacious pan-Pim Kinases Inhibitor.

ACS Med Chem Lett 2012 Feb 27;3(2):135-9. Epub 2011 Dec 27.

Cylene Pharmaceuticals Inc. , 5820 Nancy Ridge Drive, Suite 200, San Diego, California 92121, United States.

Structure-activity relationship analysis in a series of 3-(5-((2-oxoindolin-3-ylidene)methyl)furan-2-yl)amides identified compound 13, a pan-Pim kinases inhibitor with excellent biochemical potency and kinase selectivity. Compound 13 exhibited in vitro synergy with chemotherapeutics and robust in vivo efficacy in two Pim kinases driven tumor models.
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http://dx.doi.org/10.1021/ml200259qDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4025662PMC
February 2012

Design and synthesis of Hsp90 inhibitors: exploring the SAR of Sansalvamide A derivatives.

Bioorg Med Chem 2010 Sep 22;18(18):6822-56. Epub 2010 Jul 22.

Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1030, United States.

Utilizing the structure-activity relationship we have developed during the synthesis of the first two generations and mechanism of action studies that point to the interaction of these molecules with the key oncogenic protein Hsp90, we report here the design of 32 new Sansalvamide A derivatives and their synthesis. Our new structures, designed from previously reported potent compounds, were tested for cytotoxicity on the HCT116 colon cancer cell line, and their binding to the biological target was analyzed using computational studies involving blind docking of derivatives using Autodock. Further, we show new evidence that our molecules bind directly to Hsp90 and modulate Hsp90's binding with client proteins. Finally, we demonstrate that we have integrated good ADME properties into a new derivative.
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http://dx.doi.org/10.1016/j.bmc.2010.07.042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2933939PMC
September 2010

Synthesis and biological evaluation of histone deacetylase inhibitors that are based on FR235222: a cyclic tetrapeptide scaffold.

Bioorg Med Chem Lett 2008 Apr 20;18(8):2549-54. Epub 2008 Mar 20.

Department of Chemistry and Biochemistry, 5500 Campanile Drive, San Diego State University, San Diego, CA 92182, USA.

We outline the synthesis of six novel derivatives that are based on a recently discovered HDAC inhibitor FR235222. Our work is the first report utilizing a novel binding element, guanidine, as metal coordinators in HDAC inhibitors. Further, we demonstrate that these compounds show cytotoxicity that parallels their ability to inhibit deacetylase activity, and that the most potent compounds maintain an L-Phe at position 1, and a D-Pro at position 4. Both inhibition of HDAC activity and cytotoxicity against the pancreatic cancer cell line BxPC3 are exhibited by these compounds, establishing that a guanidine unit can be utilized successfully to inhibit HDAC activity.
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http://dx.doi.org/10.1016/j.bmcl.2008.03.047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2593638PMC
April 2008

Synthesis of second-generation sansalvamide A derivatives: novel templates as potential antitumor agents.

J Org Chem 2007 Mar 22;72(6):1980-2002. Epub 2007 Feb 22.

Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, California 92182-1030, USA.

We report the synthesis of 34 second-generation Sansalvamide A derivatives. San A derivatives have unique anticancer properties and target multiple cancers, including colon, pancreatic, breast, prostate, and melanoma. As novel templates, the derivatives described herein explore the role of stereochemistry, amide bond geometry, transannular hydrogen bonding, and polarity on antitumor potency. Testing the chemotherapeutic activity of these derivatives against multiple cancer cell lines will provide clear structural motifs and identify conformational space that is important for cytotoxicity. The 34 compounds presented are divided into six series, where five series involve the insertion of D-amino acids in conjunction with four structural features at each of the five positions of the macrocycle. The sixth series involves comparison between all L- and all D-amino acid derivatives with N-methyls placed at each position around the macrocyclic core. The four structural features explored in conjunction with D-amino acids include N-methyl amino acids, aromatic amino acids, polar amino acids, and hydrophobic alkyl amino acids.
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http://dx.doi.org/10.1021/jo061830jDOI Listing
March 2007