Antioxidant and Anti-Inflammatory Effects of Camellia nitidissima Chi Ethanolic Extract in DSS-Induced Ulcerative Colitis: Phenolic Profiling and In Silico Docking Insight Into Fisetin’s Molecular Targets

Abstract

This study investigated the effect of a polyphenolic ethanolic extract from Camellia nitidissima Chi (CNFC) flowers on the reduction of DSS-induced ulcerative colitis in a C57BL/6 mouse model by regulating antioxidant and anti-inflammatory mechanisms. The interaction of the fisetin molecule with essential anti-inflammatory proteins (NF-κB and NLRP3) and the antioxidant protein Keap1 was examined through molecular docking analysis. The phenolic content in CNFC was measured at 2.09 mg/g, while the flavonoid content was 2.80 mg/g. The ethanolic extract of CNFC showed IC₅₀ values of 0.605, 0.862, and 0.299 mg/mL against DPPH, ABTS, and OH·, respectively, indicating robust antioxidant activity. Three phenolic compounds have been identified for the first time in CNFC flowers: 6-hydroxyflavone, fisetin, and (2S,3S,4S,5R,6S)-6-[2-(3,4-dihydroxyphenyl)-5-hydroxy-4-oxochromen-7-yl]oxy-3,4,5-trihydroxyoxane-2-carboxylic acid. The model group mice experienced greater weight loss and had a colon length of 45 mm, much shorter than the intervention group’s 65 mm. The spleen inflammation index was 62.1 mg/10 g, markedly higher than the 44.2 mg/10 g in the intervention group. Additionally, the histopathology score of 7 exceeded that of the intervention group, as did the disease activity index score of 7, compared with the intervention group’s score of 1. The binding interactions of fisetin with NF-κB, Keap1, and NLRP3 proteins indicate a potential affinity for these proteins. CNFC exhibits notable antioxidant and anti-inflammatory properties, and this study offers a technical reference and theoretical foundation for advancing CNFC as a functional and therapeutic food. The present study was designed to elucidate the antioxidant and anti-inflammatory mechanisms of CNFC in DSS-induced colitis, which may serve as a reference for future studies of the multiomics profiles of CNFC’s therapeutic activity, such as gut microbiome profiling, Western blotting, and qPCR-based assessment of related gene expression, for a more detailed understanding.