Cell Reporter-Based Analysis of Anti-Inflammasome Activities of Flavonoids with Distinct Structures

Abstract

Flavonoids are natural compounds that have shown promise against chronic inflammation. Despite sharing a common core scaffold, flavonoids exhibit substantial structural heterogeneity, and comparisons of biological activities across subclasses remain limited. These studies are often constrained by the cost and sensitivity limitations of conventional analytical approaches. The main objective of this study was to validate a cell-based reporter system, HEK-Blue IL-1R cells, as an alternative to immunoassays for assessing flavonoid structure–activity relationships on the modulation of inflammasome-driven IL-1β secretion by macrophages. Under mild inflammatory stimulation with lipopolysaccharide (LPS), the reporter displayed sensitive and efficient detection of low-level IL-1β signaling. In a comparative analysis of three flavonoids differing in polarity and glycosylation, quercetin, a polar aglycone, and nobiletin, a methoxylated aglycone, significantly inhibited reporter responses relative to LPS-stimulated controls, with a trend toward greater inhibition detected for quercetin. In contrast, no inhibitory effect was detected for rutin, a glycosylated derivative of quercetin. These findings were consistent with the expression of NLRP3 inflammasome proteins responsible for IL-1β maturation and secretion. Collectively, these results support the potential of flavonoid aglycones against inflammasome-associated inflammation and highlight the HEK-Blue IL-1R reporter system as a sensitive and cost-effective platform for screening IL-1β signaling under conditions of low-grade inflammation.