Design and discovery of novel heteroaryl substituted pregnenolone derivatives as potent anti-neuroinflammatory agents targeting LPS-stimulated BV-2 microglial cells

Abstract

A new family of steroidal compounds based on a heteroaryl-4,5-dihydropyrazole thiazolinone core structure was designed and synthesized through structural modifications. The anti-neuroinflammatory activity of these compounds was evaluated in lipopolysaccharide (LPS)-stimulated murine microglial BV-2 cells in vitro. Among the synthesized compounds, 10b and 10d effectively inhibited nitric oxide (NO) production, with compound 10b emerging as the most potent anti-neuroinflammatory agent (IC₅₀ = 2.05 μM). Compound 10b demonstrated significantly greater inhibitory effects than progesterone (prog) (IC₅₀ = 3.23 μM) and reduced NO production in a concentration-dependent manner. Furthermore, compound 10b attenuated the release of pro-inflammatory mediators, including tumour necrosis factor (TNF)-α, interleukin-1β (IL-1β), interleukin-6 (IL-6), and prostaglandin E2 (PGE2). It also inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Mechanistic studies revealed that compound 10b significantly suppressed the transcriptional activity of nuclear factor kappa B (NF-κB) in activated microglial cells and prevented NF-κB p65 activation and IκBα degradation. These effects were likely mediated by the inhibition of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) signaling pathways. Additionally, molecular docking studies suggested that the anti-neuroinflammatory effects of compound 10b may result from its hydrophobic and hydrophilic interactions with iNOS and COX-2, supporting its proposed mechanism of action. In summary, these findings suggest that compound 10b exerts anti-neuroinflammatory effects in LPS-stimulated BV-2 microglial cells by modulating key inflammatory pathways, including NF-κB and MAPK signaling.