Therapeutic Potential of Allium cepa in Ulcerative Colitis: Mechanistic Insights, Preclinical Evidence and Future Perspectives

Ulcerative colitis (UC), a major subtype of inflammatory bowel disease, is a chronic inflammatory disorder characterized by continuous mucosal inflammation extending from the rectum through the colon. Its pathogenesis involves complex interactions among genetic susceptibility, environmental triggers, epithelial barrier dysfunction, immune dysregulation, and gut microbiota imbalance. Activation of NF-κB and MAPK signaling pathways promotes excessive production of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6, leading to sustained mucosal injury. Although conventional therapies, including 5-aminosalicylic acid derivatives and corticosteroids, effectively control inflammation, their long-term use is limited by adverse effects. Allium cepa (onion), particularly its major flavonoid quercetin, has emerged as a promising natural therapeutic candidate in ulcerative colitis management. Preclinical studies using DSS-induced colitis model, TNBS-induced colitis model, and acetic acid–induced colitis models demonstrate that quercetin-rich onion extracts attenuate disease severity by inhibiting NF-κB and MAPK activation, reducing pro-inflammatory cytokine production, suppresing oxidative stress, modulating apoptosis, enhancing short-chain fatty acid production, promoting beneficial gut microbiota such as Bifidobacterium and Lactobacillus species, and supporting epithelial barrier integrity. Collectively, these findings highlight the therapeutic potential of quercetin-rich Allium cepa in ulcerative colitis management