Inhibitory Effects of N-Amido-3,3-difluoropyrrolidin-2-ones on LPS-induced Nitric Oxide Production in RAW 264.7 Macrophages

Abstract

Nitric oxide (NO) plays an important role in a variety of physiological processes such as platelet inhibition, blood pressure homeostasis, neurotransmission, immune responses, and especially, inflammation which is known as the central feature of many pathophysiological conditions in response to the tissue injuries and host defenses against the invading microbes. Macrophages are the main pro-inflammatory cells responsible for invading pathogens by releasing many pro-inflammatory molecules, especially the short-lived free radical NO, a product of the oxidation of L-arginine to Lcitrulline catalyzed by nitric oxide synthase (NOS). Three isoforms of NOS have been identified: two constitutive NOSs, such as endothelial NOS (eNOS) and neuronal NOS (nNOS) which are regulated by Ca, and one inducible NOS (iNOS) which is independent of Ca regulation. Activated macrophages transcriptionally express iNOS, responsible for the profound production of NO. The aberrant release of NO can lead to the amplification of inflammation as well as the tissue injury. Therefore, the pharmacological interference in the expression of iNOS presents a promising chemotherapeutic strategy to control the potentially harmful pro-inflammatory activity of macrophages. Although many anti-inflammatory agents have been investigated, there still remains a large demand for developing new and effective ones. As previously reported, the difluoromethylene-contained compounds showed the significant physiological activities such as antibiotic, anti-human immunodeficiency virus (HIV), antihypertensive, and anticancer effects. However, there has been no report about the synthesis and biological evaluation of N-amido-2-pyrrolidinones derivatives so far. The aim of this study is to investigate the inhibitory activity of N-amido-3,3-difluoropyrrolidin-2-ones derivatives against the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages with the hope that they would be recognized as the useful scaffolds for developing the new anti-inflammatory agents.