Development of a pharmacophore model for the catecholamine release-inhibitory peptide catestatin: Virtual screening and functional testing identify novel small molecule therapeutics of hypertension Igor F. Tsigelny a,b,c,⇑,  , Valentina L. Kouznetsova b,c,  , Nilima Biswas d,e , Sushil K. Mahata d,e,f , Daniel T. O’Connor d,e a Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093, United States b San Diego Supercomputer Center, University of California at San Diego, La Jolla, CA 92093, United States c Moores Cancer Center, University of California at San Diego, La Jolla, CA 92093, United States d Department of Medicine, University of California at San Diego, La Jolla, CA 92093, United States e Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, United States f Veterans Affairs San Diego Healthcare System, San Diego, CA 92161, United States article info Article history: Received 21 May 2013 Revised 27 June 2013 Accepted 3 July 2013 Available online 17 July 2013 Keywords: Catestatin Hypertension Pharmacophore Pharmacophore annotation Molecular database screening Molecular database search Molecular fingerprint Similarity clustering abstract The endogenous catecholamine release-inhibitory peptide catestatin (CST) regulates events leading to hypertension and cardiovascular disease. Earlier we studied the structure of CST by NMR, molecular mod- eling, and amino acid scanning mutagenesis. That structure has now been exploited for elucidation of interface pharmacophores that mediate binding of CST to its target, with consequent secretory inhibition. Designed pharmacophore models allowed screening of 3D structural domains. Selected compounds were tested on both cultured catecholaminergic cells and an in vivo model of hypertension; in each case, the candidates showed substantial mimicry of native CST actions, with preserved or enhanced potency and specificity. The approach and compounds have thus enabled rational design of novel drug candidates for treatment of hypertension or autonomic dysfunction. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Hypertension is the most common and lethal of cardiovascular risk factors, 1 yet despite pharmacological advances, it remains only partially controlled by antihypertensive medications. 2 Here we tar- geted the novel catecholamine storage/release hormone catestatin for therapeutic potential, by analysis of its pharmacophore fea- tures, yielding a family of small organic compounds with preserved potency and pathway specificity. Chromogranin A (CHGA, OMIM 118910), is the 48 kDa protein found in catecholamine secretory vesicles of chromaffin cells and postganglionic sympathetic axons. 3–7 CHGA contains characteristic sites for proteolytic cleavage 4 by which it is transformed to biolog- ically active peptides: pancreastatin (hCHGA 250–301 ), 8–10 prochro- macin (bCHGA 79–431 ), 11 vasostatin (hCHGA 1–76 ), 12 and catestatin (CST: bovine CHGA 344–364 : RSMRLSFRARGYGFRGPGLQL; human CHGA 352–372 : SSMKLSFRARGYGFRGPGPQL), 13,14 a well character- ized inhibitor of catecholamine release 14 working as antagonist at neuronal nicotinic acetylcholine receptors. 15 In human patients with hereditary hypertension, or their offspring, the concentration of CST in the plasma is diminished, suggesting that its deficiency can play a pathogenic role in development of hypertension. 16–18 Targeted ablation of the CHGA locus in the mouse results in unbri- dled hypertension 19 that can be ‘rescued’ by administration of CHGA’s catecholamine release-inhibitory catestatin fragment. 19 The catestatin fragment of CHGA exerts both antihypertensive 19–21 0968-0896/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.bmc.2013.07.008 Abbreviations: 3D, three-dimensional; AchR, acetylcholine receptor; ASA, water- accessible surface area; BP, blood pressure; CHGA, chromogranin A; CST, catestatin; DBP, diastolic blood pressure; DSI, Data Sciences International (St. Paul, MN); HR, heart rate; NMR, nuclear magnetic resonance; SBP, systolic blood pressure; SEM, standard error of the mean. ⇑ Corresponding author. Tel.: +1 (858) 822 0953; fax: +1 (858) 822 3631. E-mail address: itsigeln@ucsd.edu (I.F. Tsigelny).   These authors contributed equally to this work. Bioorganic & Medicinal Chemistry 21 (2013) 5855–5869 Contents lists available at SciVerse ScienceDirect Bioorganic & Medicinal Chemistry journal homepage: www.elsevier.com/locate/bmc