Subharekha Raghavan

Discovery of a Biaryl Cyclohexene Carboxylic Acid (MK-6892): A Potent and Selective High Affinity Niacin Receptor Full Agonist with Reduced Flushing Profiles in Animals as a Preclinical Candidate

Biaryl cyclohexene carboxylic acids were discovered as full and potent niacin receptor (GPR109A) agonists. Compound 1e (MK-6892) displayed excellent receptor activity, good PK across species, remarkably clean off-target profiles, good ancillary pharmacology, and superior therapeutic window over niacin regarding the FFA reduction versus vasodilation in rats and dogs.

Tetrahydro anthranilic acid as a surrogate for anthranilic acid : Application to the discovery of potent niacin receptor agonists

The design, synthesis, and biological activity of a series of cycloalkene acid-based niacin receptor agonists are described. This led to the discovery that tetrahydro anthranilic acid is an excellent surrogate for anthranilic acid. Several compounds were identified that were potent against the niacin receptor, had enhanced cytochrome P450 selectivity against subtypes CYP2C8 and CYP2C9, and improved oral exposure in mice.

Anthranilic acid replacements in a niacin receptor agonist.

Niacin is an effective drug for raising HDL cholesterol. However, niacin must be taken in large doses and significant side effects are often observed, including facial flushing, loss of glucose tolerance, and liver toxicity. An anthranilic acid was identified as an agonist of the niacin receptor. In order to improve efficacy and provide structural diversity, replacements for the anthranilic acid were investigated and several compounds with improved properties were identified.

Design and synthesis of highly potent HIV protease inhibitors with activity against resistant virus

A series of highly potent HIV protease inhibitors have been designed and synthesized. These compounds are active against various clinical viral isolates as well as wild-type virus. The synthesis and biological activity of these HIV protease inhibitors are discussed.

Pyrazole acids as niacin receptor agonists for the treatment of dyslipidemia.

Niacin is an effective drug for raising HDL cholesterol and reducing coronary risks, but patients show low compliance with treatment due to severe facial flushing upon taking the drug. A series of bicyclic pyrazole carboxylic acids were synthesized and tested for their ability to activate the niacin receptor. One analog, 23, showed improved potency and lacked flushing at doses that effectively altered the lipid profile of rats.

The discovery of high affinity agonists of GPR109a with reduced serum shift and improved ADME properties

Amino-anthranilic acid derivatives have been identified as a new class of low serum shifted, high affinity full agonists of the human orphan G-protein-coupled receptor GPR109a with improved ADME properties.

GPR109a agonists. Part 1: 5-Alkyl and 5-aryl-pyrazole–tetrazoles as agonists of the human orphan G-protein coupled receptor GPR109a

5-Alkyl and aryl-pyrazole-tetrazoles have been identified as a new class of selective, small-molecule, agonists of the human G-protein-coupled receptor GPR109a, a high affinity receptor for the HDL-raising drug nicotinic acid.

GPR109a agonists. Part 2: Pyrazole-acids as agonists of the human orphan G-protein coupled receptor GPR109a

5-Alkyl and aryl-pyrazole-acids have been identified as a new class of selective, small-molecule, agonists of the human orphan G-protein-coupled receptor GPR109a, a high affinity receptor for the HDL-raising drug nicotinic acid.

Targeting native and apo-sGC

Soluble guanylate cyclase (sGC), the receptor for nitric oxide (NO), is one component of the nitric oxide (NO)-sGC-cGMP signaling pathway, which plays a key role in the cardiovascular system regulating smooth muscle relaxation and vasodilation and has been implicated in remodeling events in the heart and vasculature. Triggered by the binding endothelial-derived NO to the prosthetic heme group, sGC in smooth muscle cells converts GTP to the secondary messenger cGMP. Small molecule activators of sGC have been identified that either have the ability to activate the native heme-containing form of the enzyme (Heme-Dependent activators) or have the ability to activate to heme-free or oxidized form of the enzyme (Heme-Independent activators). The therapeutic potential of activators of sGC is illustrated by the successful clinical evaluation by Bayer of a Heme-dependent activator riociguat in pulmonary arterial hypertension [1]. The characterization of both heme-dependent and heme-independent activators with regard to their biochemical interactions with the enzyme as well as preclinical in vivo activity in rodent models of systemic and pulmonary hypertension will be presented.

Selective Formation of Functionalized α-Quaternary Malononitriles toward 5,5-Disubstituted Pyrrolopyrimidinones

A modular, selective approach to complex α-tertiary substituted malononitriles is reported. The method takes advantage of β-ester-substituted α,α-dinitrile alkenes as highly reactive, chemoselective electrophiles for 1,4-additions with organometallic nucleophiles to produce functionally and sterically dense all-carbon quaternary centers. In the presence of a chiral ester auxiliary bearing an aromatic ring, the 1,4-addition occurs with good to excellent selectivity due to favorable cation-π interactions. The highly functionalized malononitriles represent versatile building blocks and can be applied toward efficient, highly selective syntheses of 5,5-disubstituted pyrrolopyrimidinones.