Developing Dual and Specific Inhibitors of Dimethylarginine Dimethylaminohydrolase-1 and Nitric Oxide Synthase: Toward a Targeted Polypharmacology To Control Nitric Oxide

Abstract

Molecules that block nitric oxide's (NO) biosynthesis are of significant interest. For example, nitric oxide synthase (NOS) inhibitors have been suggested as anti-tumor therapeutics, as have inhibitors of dimethylarginine dimethylaminohydrolase (DDAH), an enzyme that catabolizes endogenous NOS inhibitors. Dual-targeted inhibitors hold promise as more effective reagents to block NO biosynthesis than single-targeted compounds. In this study, a small set of known NOS inhibitors are surveyed as inhibitors of recombinant human DDAH-1. From these, an alkylamidine scaffold is selected for homologation. Stepwise lengthening of one substituent converts an NOS-selective inhibitor into a dual-targeted NOS/DDAH-1 inhibitor and then into a DDAH-1 selective inhibitor, as seen in the inhibition constants of N5-(1-iminoethyl)-, N5-(1-iminopropyl)-, N5-(1-iminopentyl)- and N5-(1-iminohexyl)-l-ornithine for neuronal NOS (1.7, 3, 20, >1,900 μM, respectively) and DDAH-1 (990, 52, 7.5, 110 μM, respectively). A 1.9Å X-ray crystal structure of the N5-(1-iminopropyl)-l-ornithine : DDAH-1 complex indicates covalent bond formation between the inhibitor's amidino carbon and the active-site Cys274, and solution studies show reversible competitive inhibition, consistent with a reversible covalent mode of DDAH inhibition by alkylamidine inhibitors. These represent a versatile scaffold for the development of a targeted polypharmacological approach to control NO biosynthesis.

The DDAH/NOS pathway in human prostatic cancer cell lines: Antiangiogenic effect of L-NAME

“…9). Moreover, since L-NAME was unable to reduce DDAH activity and expression, as reported by Wang et al (84), it is plausible to hypothesize the development of a targeted polypharmacological approach by developing dual and specific inhibitors of DDAH and NOS to better control NO biosynthesis.…”

A Novel and Potent Inhibitor of Dimethylarginine Dimethylaminohydrolase: A Modulator of Cardiovascular Nitric Oxide

“…*P , 0.05 versus 50 mM; **P , 0.05 between 100 and 1000 mM substrate concentration. The Michaelis constant (K M ) for SMTC is~3 mM (Wang et al, 2009). Fig.…”

“…We and others have applied high-throughput screening to discover small molecules that regulate the nitric oxide (NO) synthase (NOS)/dimethylarginine dimethylaminohydrolase (DDAH) pathway (Hartzoulakis et al, 2007;Kotthaus et al, 2008;Wang et al, 2009;Fast, 2011, 2012;Ghebremariam et al, 2012Ghebremariam et al, , 2013. This scientific interest stems from the essential biologic role that the NOS/ DDAH pathway plays in metabolic, cardiovascular, pulmonary, immune, and nervous systems (Palm et al, 2007;Leiper and Nandi, 2011).…”

Designing modulators of dimethylarginine dimethylaminohydrolase (DDAH): A focus on selectivity over arginase

“…Additionally, 2c and 2e represent potent DDAH inhibitors possessing a moderate selectivity over arginase; however, as for 1b these compounds are not selective over NOSs. Nevertheless, these compounds might represent interesting model compounds since other authors claim the dual inhibition of NOSs and DDAH as a promising pharmaceutical strategy 11 . 2b and 2d are other compounds that slightly more potently affected arginase activity limiting their applicability in further studies.…”

“…However, most of these l-arginine analogues additionally affect NOSs activity 7,[10][11][12] . In fact, it is still a matter of debate whether selectivity over NOSs is essentially needed, considering that inhibition of both NOSs and DDAH represents a dual mode of action and should increase potency of .…”