Flavonoid profiling of Plumula nelumbinis and evaluation of their anti-inflammatory effects on lipopolysaccharide-induced RAW 264.7 macrophages

The lotus seed embryo, known as “Plumula nelumbinis,” holds significance in Chinese culture as a traditional medicinal and edible herb rich in beneficial bioactive compounds like flavonoids, alkaloids, and polyphenols. Using ultrahigh-performance liquid chromatography-quadrupole-exactive Orbitrap mass spectrometry, we meticulously analyzed the total flavonoids in Plumula nelumbinis (PNF) sourced from Hangzhou's West Lake. Our investigation preliminarily identified 29 flavonoid compounds, including 21 flavonoid O-glycosides, five flavonoid C-glycosides, and three aglycones, through comparisons with standards and literature references. Subsequent cellular anti-inflammatory experiments using lipopolysaccharide (LPS)-induced RAW264.7 cells demonstrated that treatment with 300 μg/mL of lotus seed flavonoids significantly reduced inflammatory factors' production, such as nitric oxide, prostaglandin E₂, tumor necrosis factor, interleukin-6, and interleukin-1β. Additionally, PNF effectively lowered intracellular reactive oxygen species levels, mitigated LPS-induced cell apoptosis, and nuclear translocation of nuclear factor-κB (NF-κB) p65 protein, collectively suppressing the NF-κB p65 inflammatory pathway and demonstrating potent anti-inflammatory properties. Crucially, the observed gene expression patterns of inflammatory factors aligned with their respective protein secretion levels. This study provides a comprehensive exploration of lotus seed flavonoids' anti-inflammatory potential, highlighting their significance in potential therapeutic applications and laying the groundwork for future advancements in related functional foods.