Protective effect of Lachnum polysaccharide on dextran sulfate sodium-induced colitis in mice

Qingzhuan dark tea polysaccharides-zinc alleviates dextran sodium sulfate-induced ulcerative colitis

BACKGROUND

Qingzhuan dark tea polysaccharides (QDTP) have been complexed with Zinc (Zn) to form the Qingzhuan dark tea polysaccharides-Zinc (QDTP-Zn) complex. The present study investigated the protective effects of QDTP-Zn on ulcerative colitis (UC) in mice. The UC mouse model was induced using dextran sodium sulfate (DSS), followed by oral administration of QDTP-Zn (0.2 and 0.4 g kg-1 day-1).

RESULTS

QDTP-Zn demonstrated alleviation of UC symptoms in mice, as evidenced by a decrease in disease activity index scores. QDTP-Zn also regulated colon tissue injury by upregulating ZO-1 and occludin protein expression, at the same time as downregulating tumor necrosis factor-α and interleukin-6β levels. Furthermore, QDTP-Zn induced significant alterations in the abundance of bacteroidetes and firmicutes and notably increased levels of short-chain fatty acids (SCFAs), particularly acetic acid, propionic acid, and butyric acid.

CONCLUSION

In summary, QDTP-Zn exhibits therapeutic potential in alleviating enteritis by fortifying the colonic mucosal barrier, mitigating inflammation and modulating intestinal microbiota and SCFAs levels. Thus, QDTP-Zn holds promise as a functional food for both the prevention and treatment of UC. © 2024 Society of Chemical Industry.

Alleviative effects of exopolysaccharides from Limosilactobacillus mucosae CCFM1273 against ulcerative colitis via modulation of gut microbiota and inhibition of Fas/Fasl and TLR4/NF-κB pathways

Ulcerative colitis (UC) has become a public health challenge as its global prevalence increases annually. The use of prebiotics in healthcare has grown in recent years. Thus, the present study was designed to explore the alleviating effects and mechanisms of exopolysaccharides (EPS) produced by Limosilactobacillus mucosae CCFM1273 on UC. The results indicated that CCFM1273 EPS mitigated the disease symptoms and colonic pathologic damage in DSS-induced colitis mice. Moreover, CCFM1273 EPS improved the intestinal barrier by restoring goblet cell numbers and MUC2 production, enhancing intercellular junctions, and inhibiting epithelial cell apoptosis. In addition, CCFM1273 EPS inhibited colonic inflammation and oxidative stress. Importantly, CCFM1273 EPS augmented short-chain fatty acid (SCFA) producers, leading to increased levels of SCFAs (especially propionic acid), which inhibited the Fas/Fasl pathway and consequently inhibited epithelial apoptosis, and diminished Gram-negative bacteria, further decreasing lipopolysaccharides (LPS), which suppressed the TLR4/NF-κB pathway and consequently suppressed colonic inflammation, eventually relieving UC in mice. This study provides theoretical support for the use of prebiotics in clinical practice for UC.

The protective effect of Schisandra chinensis (Turcz.) Baill. polysaccharide on DSS-induced ulcerative colitis in mice via the modulation of gut microbiota and inhibition of NF-κB activation

BACKGROUND

Schisandra chinensis (Turcz.) Baill, a fruit utilized in traditional Chinese medicine (TCM), has a long history of medical application. It has been used to treat diseases of the gastrointestinal tract. Schisandra chinensis (Turcz.) Baill polysaccharide (SACP) is an important biologically active ingredient that has been shown to have a variety of beneficial effects including immune regulation and anti-oxidative properties. Ulcerative colitis (UC) is a complicated gastrointestinal inflammatory disease. We explore the protective effect of SACP against UC.

RESULTS

Schisandra chinensis (Turcz.) Baill polysaccharide significantly reduced the disease activity index (DAI) and levels of myeloperoxidase(MPO) and malondialdehyde (MDA) in colonic tissue. It also alleviated weight loss and histopathological damage of mice. The expression of MUC2 and occludin proteins was increased and the barrier function of the colonic mucosa was enhanced by SACP treatment. NF-κB pathway activation was also inhibited and the production of pro-inflammatory cytokines was decreased whereas anti-inflammatory cytokines were increased. 16SrDNA sequencing of fecal flora showed that SACP increased the abundance of Muribaculaceaeunclassified, LachnospiraceaeNK4A136group and reduced the abundance of Bacteroides and Erysipelatoclostridium.

CONCLUSION

Schisandra chinensis (Turcz.) Baill polysaccharide can protect against Dextran Sulfate Sodium Salt (DSS)-induced ulcerative colitis in mice. © 2023 Society of Chemical Industry.

NOD-like receptors mediate homeostatic intestinal epithelial barrier function: promising therapeutic targets for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic gastrointestinal inflammatory disease that involves host genetics, the microbiome, and inflammatory responses. The current consensus is that the disruption of the intestinal mucosal barrier is the core pathogenesis of IBD, including intestinal microbial factors, abnormal immune responses, and impaired intestinal mucosal barrier. Cumulative data show that nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) are dominant mediators in maintaining the homeostasis of the intestinal mucosal barrier, which play critical roles in sensing the commensal microbiota, maintaining homeostasis, and regulating intestinal inflammation. Blocking NLRs inflammasome activation by botanicals may be a promising way to prevent IBD progression. In this review, we systematically introduce the multiple roles of NLRs in regulating intestinal mucosal barrier homeostasis and focus on summarizing the activities and potential mechanisms of natural products against IBD. Aiming to propose new directions on the pathogenesis and precise treatment of IBD.

Gallic acid ameliorates dextran sulfate sodium-induced ulcerative colitis in mice via inhibiting NLRP3 inflammasome

Background: Ulcerative colitis (UC) is a chronic recurrent inflammatory bowel disease (IBD). The conventional drugs for UC may induce severe side effects. Herbal medicine is considered as a complementary and alternative choice for UC. Purpose: This study aims to estimate the effect of natural polyphenol gallic acid (GA) on the NLRP3 inflammasome with dextran sulfate sodium (DSS)-induced colitis in mice. Study design: The body weights and symptoms of BALB/c mice were recorded. Histological evaluation, ELISA, q-PCR, immunohistochemistry, and western blotting were carried out to observe the morphology, cytokine contents, mRNA expressions, and protein expressions, respectively. Lipopolysaccharide (LPS)-induced RAW264.7 macrophage was used to probe GA's effect on relative protein expression. Results: GA attenuated weight loss (p < 0.05), relieved symptoms, and ameliorated colonic morphological injury (p < 0.05) in mice with colitis induced by DSS. GA also lowered the contents of TNF-α, IL-1β, IL-18, IL-33, and IFN-γ in the serum and colon of mice, which were elevated by DSS, downregulated protein, and mRNA expressions of the NLRP3 pathway in the colon tissue. Furthermore, GA downregulated the expressions of NLRP3 (p < 0.05), iNOS (p < 0.01), COX2 (p < 0.01), and P-p65 (p < 0.05), and suppressed NO release (p < 0.001) in LPS-induced RAW264.7 cells. Conclusion: GA ameliorated DSS-induced UC in mice via inhibiting the NLRP3 inflammasome. These findings furnish evidence for the anti-inflammatory effect of herbal medicines containing GA on UC.

Role of ER Stress Mediated Unfolded Protein Responses and ER Stress Inhibitors in the Pathogenesis of Inflammatory Bowel Disease

Previous investigations have increased the knowledge about the pathological processes of inflammatory bowel diseases. Besides the complex organization of immune reactions, the mucosal epithelial lining has been recognized as a crucial regulator in the commencement and persistence of intestinal inflammation. As the intestinal epithelium is exposed to various environmental factors, the intestinal epithelial cells are confronted with diverse cellular stress conditions. In eukaryotic cells, an imbalance in the endoplasmic reticulum (ER) might cause aggregation of unfolded or misfolded proteins in the lumen of ER, a condition known as endoplasmic reticulum stress. This cellular mechanism stimulates the unfolded protein response (UPR), which elevates the potential of the endoplasmic reticulum protein folding, improves protein production and its maturation, and also stimulates ER-associated protein degradation. Current analyses reported that in the epithelium, the ER stress might cause the pathogenesis of inflammatory bowel disease that affects the synthesis of protein, inducing the apoptosis of the epithelial cell and stimulating the proinflammatory reactions in the gut. There have been significant efforts to develop small molecules or molecular chaperones that will be potent in ameliorating ER stress. The restoration of UPR balance in the endoplasmic reticulum via pharmacological intervention might be a novel therapeutic approach for the treatment of inflammatory bowel diseases (IBDs). This review provides novel insights into the role of chemical chaperone UPR modulators to modify ER stress levels. We further discuss the future directions/challenges in the development of therapeutic strategies for IBDs by targeting the ER stress. Figure depicting the role of endoplasmic reticulum stress-mediated inflammatory bowel disease and the therapeutic role of endoplasmic reticulum stress inhibitors in alleviating the diseased condition.

Polysaccharide from Atractylodes macrocephala Koidz. ameliorates DSS-induced colitis in mice by regulating the Th17/Treg cell balance

Atractylodes macrocephala Koidz. is one of the most frequently used traditional Chinese medicines for the treatment of ulcerative colitis (UC). The beneficial effect of polysaccharide from Atractylodes macrocephala Koidz. (PAMK) on UC has been reported, while the underlying mechanism and target remain unclear. In this study, we systematically investigated the therapeutic effect and the underlying mechanism of PAMK in UC based on a mouse model of dextran sodium sulfate (DSS)-induced colitis. PAMK treatment (100 mg/kg, 200 mg/kg and 400 mg/kg) significantly ameliorated DSS-induced colitis, manifested as a reduction in weight loss, disease activity index (DAI), colon shortening, spleen index and histological score. Moreover, PAMK treatment inhibited inflammation and improved the integrity of the intestinal barrier in colitis mice. Mechanistically, microarray analysis determined the critical role of the immunoregulatory effect of PAMK in alleviating UC. Flow cytometry analysis further demonstrated that PAMK treatment regulated the balance between T helper (Th) 17 and regulatory T (Treg) cells in the mesenteric lymph nodes (MLN) and spleen in mice with colitis. In addition, PAMK treatment downregulated the expression of IL-6 and suppressed the phosphorylation of STAT3. Together, these data revealed that PAMK treatment alleviated DSS-induced colitis by regulating the Th17/Treg cell balance, which may be dependent on the inhibition of the IL-6/STAT3 signaling pathway. Our study is the first to elucidate that the underlying mechanism by which PAMK treatment alleviates DSS-induced colitis is associated with an improved the Th17/Treg cell balance. Collectively, the study provides evidence for the potential of PAMK to treat UC.

A Potential Role of Plant/Macrofungi/Algae-Derived Non-Starch Polysaccharide in Colitis Curing: Review of Possible Mechanisms of Action

Multiple in vitro and in vivo model investigations have suggested a broad spectrum of potential mechanisms by which plant/macrofungi-derived non-starch polysaccharides may play a role in the treatment of inflammatory bowel disease (IBD). This article reviews the in vivo and in vitro evidence of different plant-derived polysaccharides for IBD therapy. Their underlying mechanisms, particularly the molecular mechanisms associated with protective effects in the treatment and prevention of IDB, have been well summarized, including anti-inflammatory, epithelial barrier repair, and the regulation of intestinal flora. Emerging studies have observed the potent role of probiotics in IBD, particularly its ability to modulate gut microbiota, a well-known key factor for IBD. In summary, plant/macrofungi-derived polysaccharides have the potential to be a promising agent for the adjuvant treatment and prevention of IBD and will contribute to the design of well-designed clinical intervention trials that will ultimately improve the therapy of IBD.

Intervention and potential mechanism of non-starch polysaccharides from natural resources on ulcerative colitis: A review

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology that affects the colon and rectum. It has evolved into a global burden due to the high incidence in developed countries and the highly-increased incidence in developing countries. Non-starch polysaccharides (NSPs) from natural resources, as a type of functional carbohydrates, have a significant therapeutic effect on UC because of their good anti-inflammatory and immunomodulatory activities. Based on the etiology and pathogenesis of UC, this review summarizes the intervention effects and mechanisms of NSPs in the prevention and treatment of UC. The results showed that NSPs can improve UC by protecting the intestinal mucosal barrier, regulating the immune response of the intestinal mucosa, and remodeling the intestinal flora and metabolites. These contents provide theoretical basis for the application of polysaccharides in the prevention and treatment of UC.

Selenium-containing tea polysaccharides ameliorate DSS-induced ulcerative colitis via enhancing the intestinal barrier and regulating the gut microbiota

Both tea polysaccharides and selenium have certain remission potential for ulcerative colitis (UC), but few reports focused on natural selenium-containing tea polysaccharides. The purpose of this study was to isolate a selenium-containing tea polysaccharide (ASeTP) and determine its structure and effects on UC. Results showed that ASeTP was primarily composed of three purified, β-pyranoside-linked, protein-binding polysaccharides (SeTP-1, SeTP-2, and SeTP-3) with SeOC, OSeO, and SeO linkages. Specifically, SeTP-1 was a neutral heteropolysaccharide principally composed of mannose, glucose, galactose, xylose, and arabinose, while SeTP-2 and SeTP-3 were acidic heteropolysaccharides due to the existence of glucuronic acid. ASeTP effectively alleviated the symptoms of weight loss, colon shortens, and disease activity index scores increase in dextran sodium sulfate (DSS)-induced colitis mice. ASeTP attenuated the histological damage and maintained the colonic mucosal barrier via up-regulating the expression of occludin, claudin-1, and zona occludens-1 (ZO-1). ASeTP suppressed the levels of pro-inflammatory cytokines and enhanced the antioxidant capacity of colon tissue. Besides, ASeTP beneficially increased the selenium content of the colon. Furthermore, ASeTP remodeled the gut microbiota by accelerating the proliferation of beneficial bacteria and inhibiting pathogenic microorganisms. Thus, ASeTP has the potential to be a functional food against colitis.

Polysaccharides from Lachnum sp. Inhibited colitis-associated colon tumorigenesis in mice by modulating fecal microbiota and metabolites

It is still uncertain whether the consumption of Lachnum sp. polysaccharides (LEP) alleviates colorectal cancer (CRC) through the gut microbiota. In this study, our efforts are focused on the influence of LEP on CRC, intestinal barrier and inflammation, and fecal microbiota and the metabolites, in azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC mice. Results showed that LEP inhibited CRC mouse colon shortening and weight loss, decreased tumor incidence, restored intestinal barrier integrity, and reduced excessive inflammation. LEP consumption significantly altered microbiota overall structure and community, with reduced pernicious bacteria (such as Parabacteroides, Escherichia_Shigella, Desulfovibrio and Helicobacter), and increased beneficial bacterium (such as Alistipes, Alloprevotella and Ruminiclostridium). Fecal-metabolome profile indicated that a total of 43 metabolites were clearly changed, with 10 down-regulated and 33 up-regulated metabolites. In addition, short-chain fatty acids (SCFAs), including acetic acid, propionic acid and n-butyric acid, were significantly increased after LEP administration. Moreover, a strong correlation between the fluctuant gut microbiota and metabolites was found. These findings provided not only deeper insights into the responsibility of LEP for CRC alleviation, and but also the potential of LEP as a promising candidate for CRC prevention and treatment.

Protective effects of bioactive peptides in foxtail millet protein hydrolysates against experimental colitis in mice

It is of great significance to develop a dietary intervention strategy to prevent inflammatory bowel disease (IBD). A millet-rich diet can ameliorate IBD, but the active ingredients and mechanisms remain to be studied. Our results showed that the oral administration of foxtail millet protein hydrolysates (FMPH) reduced the disease activity index (DAI) score and improved the colon symptoms of dextran sulfate sodium (DSS)-induced colitis mice. FMPH reduced the serum LPS level, increased intestinal ZO-1 and occludin expression, inhibited NF-κB phosphorylation, and reduced the levels of TNF-α and IL-6. Further, FMPH inhibited Th17 cell differentiation, and inhibited inflammasome activation and IL-1β expression through the NLRP3/ASC/caspase-1 pathway. The results on Caco-2 cells confirmed the role of FMPH on tight junction and inflammasomes activation. A total of 2620 peptides were identified in FMPH by UPLC-MS/MS, of which 22 peptides were predicted as potential biopeptides, and the key sequences were LPF, ANP, PY, YW, and IPP. This study supports the effect of a diet rich in millet on the improvement of IBD and provides a scientific basis for the use of millet protein as a functional food to improve intestinal inflammation.

Modulatory Properties of Food and Nutraceutical Components Targeting NLRP3 Inflammasome Activation

Inflammasomes are key intracellular multimeric proteins able to initiate the cellular inflammatory signaling pathway. NLRP3 inflammasome represents one of the main protein complexes involved in the development of inflammatory events, and its activity has been largely demonstrated to be connected with inflammatory or autoinflammatory disorders, including diabetes, gouty arthritis, liver fibrosis, Alzheimer’s disease, respiratory syndromes, atherosclerosis, and cancer initiation. In recent years, it has been demonstrated how dietary intake and nutritional status represent important environmental elements that can modulate metabolic inflammation, since food matrices are an important source of several bioactive compounds. In this review, an updated status of knowledge regarding food bioactive compounds as NLRP3 inflammasome modulators is discussed. Several chemical classes, namely polyphenols, organosulfurs, terpenes, fatty acids, proteins, amino acids, saponins, sterols, polysaccharides, carotenoids, vitamins, and probiotics, have been shown to possess NLRP3 inflammasome-modulating activity through in vitro and in vivo assays, mainly demonstrating an anti-NLRP3 inflammasome activity. Plant foods are particularly rich in important bioactive compounds, each of them can have different effects on the pathway of inflammatory response, confirming the importance of the nutritional pattern (food model) as a whole rather than any single nutrient or functional compound.

Effects of Two Polysaccharides from Lepidium meyenii (Maca) on Intestinal Immunity and Inflammation in vitro

In our previous studies, two polysaccharides (MC-1 and MC-2) were identified in the roots of maca (Lepidium meyenii). In this study, the effects of these two polysaccharides on intestinal immunity...

Natural-Derived Polysaccharides From Plants, Mushrooms, and Seaweeds for the Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease impairing the gastrointestinal tract, and its incidence and prevalence have been increasing over time worldwide. IBD greatly reduces peoples' quality of life and results in several life-threatening complications, including polyp, toxic colonic dilatation, intestinal perforation, gastrointestinal bleeding, and cancerization. The current therapies for IBD mainly include drugs for noncritical patients and operation for critical patients. However, continuous use of these drugs causes serious side effects and increased drug resistance, and the demand of effective and affordable drugs with minimal side effects for IBD sufferers is urgent. Natural-derived polysaccharides are becoming a research hotspot for their therapeutic effects on IBD. This study focuses on the research progress of various natural polysaccharides from plants, seaweeds, and mushrooms for the treatment of IBD during recent 20 years. Regulation of oxidative stress, inflammatory status, gut microbiota, and immune system and protection of the intestinal epithelial barrier function are the underlying mechanisms for the natural-derived polysaccharides to treat IBD. The excellent efficacy and safety of polysaccharides make them promising candidates for IBD therapy.

Biological functions of NLRP3 inflammasome: A therapeutic target in inflammatory bowel disease

Cases of inflammatory bowel disease (IBD), a debilitating intestinal disorder with complex pathological mechanisms, have been increasing in recent years, straining the capacity of healthcare systems. Thus, novel therapeutic targets and innovative agents must be developed. Notably, the NLRP3 inflammasome is upregulated in patients with IBD and/or in animal experimental models. As an innate immune supramolecular assembly, the NLRP3 inflammasome is persistently activated during the pathogenesis of IBD by multiple stimuli. Moreover, this protein complex regulates pro-inflammatory cytokines. Thus, targeting this multiprotein oligomer may offer a feasible way to relieve IBD symptoms and improve clinical outcomes. The mechanisms by which the NLRP3 inflammasome is activated, its role in IBD pathogenesis, and the drugs administered to target this protein complex are reviewed herein. This review establishes that the use of inflammasome-targeting drugs are effective for IBD treatment. Moreover, this review suggests that the value and potential of naturally sourced or derived medicines for IBD treatment must be recognized and appreciated.

Inflammasome Regulation: Therapeutic Potential for Inflammatory Bowel Disease

Inflammasomes are multiprotein complexes formed to regulate the maturation of pro-inflammatory caspases, in response to intracellular or extracellular stimulants. Accumulating studies showed that the inflammasomes are implicated in the pathogenesis of inflammatory bowel disease (IBD), although their activation is not a decisive factor for the development of IBD. Inflammasomes and related cytokines play an important role in the maintenance of gut immune homeostasis, while its overactivation might induce excess immune responses and consequently cause tissue damage in the gut. Emerging studies provide evidence that some genetic abnormalities might induce enhanced NLRP3 inflammasome activation and cause colitis. In these cases, the colonic inflammation can be ameliorated by blocking NLRP3 activation or its downstream cytokine IL-1β. A number of natural products were shown to play a role in preventing colon inflammation in various experimental colitis models. On the other hand, lack of inflammasome function also causes intestinal abnormalities. Thus, an appropriate regulation of inflammasomes might be a promising therapeutic strategy for IBD intervention. This review aims at summarizing the main findings in these studies and provide an outline for further studies that might contribute to our understanding of the role of inflammasomes in the pathogenesis and therapeutic treatment of IBD.

The Inhibitory Effect of Artesunate on Excessive Endoplasmic Reticulum Stress Alleviates Experimental Colitis in Mice

Endoplasmic reticulum (ER) stress may contribute to the pathogenesis and perpetuation of ulcerative colitis (UC). Previous studies have shown artesuante (ARS) has the protective effect on experimental UC. Therefore, it can be assumed that ARS can regulate ER stress and its related reactions. Dextran sulfate sodium (DSS) induced UC model in mice was used to testify this hypothesis. The results clearly showed that DSS exposure caused excessive ER stress evidenced by a markedly increase of GRP78 and CHOP expression, and then activated the ER stress sensors PERK, IRE1, ATF6 and their respective signaling pathways, followed by upregulated caspases12 and lowered Bcl-2/Bax ratio. However, ARS treatment significantly inhibited the occurrence of ER stress via preventing the activation of PERK-eIF2α-ATF4-CHOP and IRE1α-XBP1 signaling pathways, concurrently ER-stress-associated apoptosis in colon tissues. Moreover, ARS treatment remarkably inhibited the activation of NF-κB and the expression levels of pro-inflammatory cytokines, improved the clinical and histopathological alterations as well as maintained the expression of claudin-1 and Muc2 in mucosal layer of colon. Notably, the classic ER stress inhibitor 4-phenyhlbutyric acid enhanced the beneficial effects of ARS; in contrast, the ER stress inducer 2-deoxy-d-glucose substantially abrogated the above-mentioned effects, uncovering the involvement of ER stress in the response. These findings indicated the protection of ARS on UC is associated with its suppressing excessive ER stress mediated intestinal barrier damage and inflammatory response. This study provides a novel aspect to understand the mechanism of ARS against UC.

Endoplasmic Reticulum Stress and Intestinal Inflammation: A Perilous Union

The intestinal tract encompasses the largest mucosal surface fortified with a fine layer of intestinal epithelial cells along with highly sophisticated network of the lamina propria immune cells that are indispensable to sustain gut homeostasis. However, it can be challenging to uphold homeostasis when these cells in the intestine are perpetually exposed to insults of both endogenous and exogenous origin. The complex networking and dynamic microenvironment in the intestine demand highly functional cells ultimately burdening the endoplasmic reticulum (ER) leading to ER stress. Unresolved ER stress is one of the primary contributors to the pathogenesis of inflammatory bowel diseases (IBD). Studies also suggest that ER stress can be the primary cause of inflammation and/or the consequence of inflammation. Therefore, understanding the patterns of expression of ER stress regulators and deciphering the intricate interplay between ER stress and inflammatory pathways in intestinal epithelial cells in association with lamina propria immune cells contribute toward the development of novel therapies to tackle IBD. This review provides imperative insights into the molecular markers involved in the pathogenesis of IBD by potentiating ER stress and inflammation and briefly describes the potential pharmacological intervention strategies to mitigate ER stress and IBD. In addition, genetic mutations in the biomarkers contributing to abnormalities in the ER stress signaling pathways further emphasizes the relevance of biomarkers in potential treatment for IBD.

Characterization of Low Molecular Weight Sulfate Ulva Polysaccharide and its Protective Effect against IBD in Mice

Inflammatory bowel disease (IBD) has been gradually considered a public health challenge worldwide. Sulfated polysaccharides, extracted from seaweed, have been shown to have an anti-inflammatory effect on the disease. In this study, LMW-ulvan, a unique sulfate Ulva polysaccharide with low molecular weight, was prepared using the enzymatic method. The structural characterization of LMW-ulvan and its protective effect on colitis induced by dextran sulfate sodium (DSS) were studied. The results showed that LMW-ulvan with molecular weight of 2.56 kDa consists of 57.23% rhamnose (Rha), 28.76% xylose (Xyl), 7.42% glucuronic acid (GlcA), and 1.77% glucose (Glc). Its backbone contains (1→3,4)-linked Rha, (1→4)-linked Xyl, and (1→4)-linked GlcA with small amounts of (1→4)-linked Rha residues; sulfate substitution was at C-3 of Rha. LMW-ulvan was found to reduce DSS-induced disease activity index, colon shortening, and colonic tissue damage, which were associated with decreased oxidative stresses and inflammation, thus improving the expression of tight junction proteins. These results indicate that LMW-ulvan is able to improve colitis and may be a promising application for IBD.