Abstract Background Ulcerative colitis (UC) is an inflammatory bowel disease characterized by the overproduction of reactive oxygen species (ROS) and the release of inflammatory mediators. Dihydroartemisinin (DHA) is a semi-synthetic active metabolite of artemisinin that has anti-inflammatory, antioxidant, and anti-fibrotic properties. Objective This study aimed to assess the therapeutic benefits of DHA on acetic acid(AA) -induced UC in rats, with particular emphasis on its anti-inflammatory effects and its influence on NFκB/TNF-α/RIPK1 necroptotic pathways. Methods Eighteen rats were allocated into control, acetic acid-induced colitis (AA), and DHA-treated (AA+DHA) groups. Colitis was caused by rectal instillation of 5 % acetic acid. DHA was supplied via intraperitoneal injection. Histological, biochemical studies of oxidative stress, inflammatory and anti-inflammatory mediators, Western blotting for TNF-α, RIPK1, and caspase 3, and immunohistochemical assessment of NFκB, TNF-α, and RIPK1, were conducted. Results DHA treatment markedly diminished macroscopic damage, disease activity index, histopathology scores, and malondialdehyde (MDA) levels, enhancing glutathione (GSH) levels. Additionally, DHA decreased serum TNF-α and IL-6 and increased IL-10. Western blotting and immunohistochemistry investigations validated the reduced expression of TNF-α, RIPK1, and caspase 3 in DHA-treated rats. Conclusion DHA demonstrates protective properties against acetic acid-induced UC by decreasing oxidative stress and inflammation, modifying TNF-α activity to regulate apoptotic and necroptotic pathways. So, DHA may be a favorable therapeutic alternative for the management of ulcerative colitis. Graphical Abstract Download: Download high-res image (169KB) Download: Download full-size image Graphical abstract showing the proposed protective mechanism of DHA against AA-induced ulcerative colitis. MDA; malondialdehyde; GSH: glutathione; TNF-α: tumor necrosis factor-α; IL-6: interleukin 6; and RIPK1: receptor-interacting protein kinase 1. Introduction Inflammatory bowel disease (IBD) is a significant global health concern, as reported by the WHO (Ng et al., 2017), it impacts many individuals globally, with a maximum occurrence in early adulthood (Zihlif et al., 2024). Ulcerative colitis (UC) is the predominant form of IBD globally, with a rapid increase in incidence. It primarily impacts the large intestine and is characterized by hemorrhage and superficial erosions and ulceration in the colonic mucosa (Sartor, 2006). Inflammation typically initiates at the rectum and spreads upwards continuously throughout the full length or partial parts of the colon (Gajendran et al., 2019), marked by episodes of relapse and remission (Baumgart and Sandborn, 2007). The symptoms of ulcerative colitis, such as colonic discomfort, hematochezia, electrolyte depletion, stomachache, cramping, and weight loss, can significantly reduce the quality of life (Zaghloul et al., 2022). Additionally, it can lead to potential complications such as intestine perforation, toxic megacolon, surgical issues, and an increased risk of colorectal malignancies (Motaghi et al., 2016). Current treatments for IBD essentially manage inflammation using anti-inflammatory and immune-suppressive agents. Nonetheless, these agents may result in significant adverse effects (D’Haens, 2007; van der Lelie et al., 2021; Zeng et al., 2022). The activation of NF-κβ regulated molecules demonstrates a significant correlation with IBD (Khor et al., 2011; Vereecke et al., 2009). Both intestinal epithelial cells and lamina propria macrophages within regions of active illness contain activated NF-κβ that start transcription of many genes involved in the pathophysiology IBD. One of these genes is TNF-α, which codes for the famous inflammatory cytokines TNF-α, that its downregulation is one of the primary therapeutic options in IBD (Kaser et al., 2010). The predominant cytokines involved in the pathophysiology of ulcerative colitis (UC) include tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and interleukin (IL)-6 (Guan and Zhang, 2017). TNF-α inhibition is one of the main therapeutic options in IBD (Wong et al., 2020). During UC, it has been observed that the epithelium of the colon participate in four distinct forms of cell death: apoptosis, pyroptosis, anoikis, and planned necrosis (necroptosis), depending on the specific cell subtypes involved (Negroni et al., 2015). upon TNF-α activation, a significant proinflammatory cytokine implicated in numerous inflammatory disorders, RIPK1 is a vital regulator of necroptosis (Holler et al., 2000; Bao et al., 2022). There is a high probability that necroptosis is a result of inflammation. The binding of ligands to tumor necrosis factor receptors (TNFR) initially triggers this inflammation, leading to the activation of receptor-interacting protein kinase 1 (RIPK1), initiating a variety of inflammatory processes (Pasparakis and Vandenabeele, 2015; Weinlich et al., 2017). The activation of RIPK1 can be initiated by the inflammatory process then it also impact inflammation by directly modulating necroptosis (Zhu et al., 2021). RIPK1 mostly regulates TNF-α induced inflammation, which, according to the cellular environment and interacting molecules, causes either necroptosis or apoptosis (Gong et al., 2019; Tao et al., 2021). In ulcerative colitis, the inflammatory response, reactive oxygen species (ROS),and NF-κB activation disrupt mucosal barrier function and intestinal integrity, resulting in apoptosis (Ashique et al., 2023). Apoptosis has been associated with the pathogenesis of inflammatory bowel disease (IBD) in numerous prior studies involving both humans and animals (Kouroumalis et al., 2023). Overproduction of the ROS seems to have a pivotal role in tissue damage and the inflammatory processes linked to ulcerative colitis. This suggests that using natural compounds could be a promising new way to treat the disease (Pastrelo et al., 2017; Tian et al., 2017). Dihydroartemisinin (DHA) is a semi-synthetic derivative and the principal active metabolite of artemisinin, a natural compound extracted from the Chinese herbal remedy Artemisia annua (Liu, 2017). DHA has proven to be an efficacious and rapid-acting antimalarial agent with minimal toxicity. In comparison to artemisinin, the solubility of DHA in water is exceptional and has enhanced antimalarial potency, demonstrating an efficacy almost 10 times greater than that of artemisinin (Dai et al., 2021). After DHA showed great promise in treating malaria in the early 1990s, Li and his colleagues started looking into its other uses (Li et al., 2006). Additionally, Liang et al. demonstrated that DHA has a protective role against IBD in mice, it suppresses the phosphorylation of p65 and p38, downregulates NLRP3 inflammasome expression, and consequently diminishes the levels of IL-1β, IL-6, and TNF-α (Liang et al., 2020). DHA has a wide range of therapeutic effects by acting on numerous organs in the body to exert anti-inflammatory, antioxidant, and anti-fibrotic effects (Li et al., 2022). So, this study aimed to investigate the effect of DHA on acetic acid-indued UC and evaluate its effect on apoptosis and TNF-α/RIPK1 necroptotic pathways via immunohistochemical staining and western blotting.