Discovery of small-molecule candidates against inflammatory bowel disease

Synthetically Feasible De Novo Molecular Design of Leads Based on a Reinforcement Learning Model: AI-Assisted Discovery of an Anti-IBD Lead Targeting CXCR4

Artificial intelligence (AI) de novo molecular generation provides leads with novel structures for drug discovery. However, the target affinity and synthesizability of the generated molecules present critical challenges for the successful application of AI technology. Therefore, we developed an advanced reinforcement learning model to bridge the gap between the theory of de novo molecular generation and the practical aspects of drug discovery. This model utilizes chemical reaction templates and commercially available building blocks as a starting point and employs forward reaction prediction to generate molecules, while real-time docking and drug-likeness predictions are conducted to ensure synthesizability and drug-likeness. We applied this model to design active molecules targeting the inflammation-related receptor CXCR4 and successfully prepared them according to the AI-proposed synthetic routes. Several molecules exhibited potent anti-CXCR4 and anti-inflammatory activity in subsequent in vitro and in vivo assays. The top-performing compound XVI alleviated symptoms related to inflammatory bowel disease and showed reasonable pharmacokinetic properties.

The Mechanism of Catalpol to Improve Oxidative Damage of Dermal Fibroblasts Based on Nrf2/HO-1 Signaling Pathway

Objective

Catalpol, as a natural medicine small-molecule drug, has been proven to have anti-inflammatory and antioxidant pharmacological effects.

Methods

The effect of catalpol on oxidative damage of mouse epidermal fibroblast L929 model and its mechanism were investigated by using hydrogen peroxide model, CCK8 method, flow cytometry, and Western blot.

Results

The effect of catalpol on Nrf2/HO-1 signaling pathway was further studied to improve oxidative stress in cell models. The results showed that catalpol had no cytotoxicity to L929 cells, and inhibited the apoptosis of L929 cells after oxidative damage in a concentration-dependent manner, thus playing a role in cell protection. The oxidative damage of cells was inhibited by up-regulating the expression of the signature protein of Nrf2/HO-1 signaling pathway and inhibiting the interstitial formation of cells.

Conclusion

This study is a preliminary study on the protective function of catalpol against oxidation and apoptosis in dermal fibroblasts, which can provide a theoretical basis and drug guidance for promoting skin wound healing in the later stage.

CXCR4/CXCL12 axis: "old" pathway as "novel" target for anti-inflammatory drug discovery

Inflammation is the body's defense response to exogenous or endogenous stimuli, involving complex regulatory mechanisms. Discovering anti-inflammatory drugs with both effectiveness and long-term use safety is still the direction of researchers' efforts. The inflammatory pathway was initially identified to be involved in tumor metastasis and HIV infection. However, research in recent years has proved that the CXC chemokine receptor type 4 (CXCR4)/CXC motif chemokine ligand 12 (CXCL12) axis plays a critical role in the upstream of the inflammatory pathway due to its chemotaxis to inflammatory cells. Blocking the chemotaxis of inflammatory cells by CXCL12 at the inflammatory site may block and alleviate the inflammatory response. Therefore, developing CXCR4 antagonists has become a novel strategy for anti-inflammatory therapy. This review aimed to systematically summarize and analyze the mechanisms of action of the CXCR4/CXCL12 axis in more than 20 inflammatory diseases, highlighting its crucial role in inflammation. Additionally, the anti-inflammatory activities of CXCR4 antagonists were discussed. The findings might help generate new perspectives for developing anti-inflammatory drugs targeting the CXCR4/CXCL12 axis.

Discovery and Optimization of Novel Nonbile Acid FXR Agonists as Preclinical Candidates for the Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a multifactorial chronic inflammation of the intestine and has become a global public health concern. A farnesoid X receptor (FXR) was recently reported to play a key role in hepatic-intestinal circulation, intestinal metabolism, immunity, and microbial regulation, and thus, it becomes a promising therapeutic target for IBD. In this study, we identified a series of nonbile acid FXR agonists, in which 33 novel compounds were designed and synthesized by the structure-based drug design strategy from our previously identified hit compound. Compound 33 exhibited a potent FXR agonistic activity, high intestinal distribution, good anti-inflammatory activity, and the ability to repair the colon epithelium in a DSS-induced acute enteritis model. Based on the results of RNA-seq analysis, we further investigated the therapeutic potential of the combination of compound 33 with 5-ASA. Overall, the results indicated that compound 33 is a promising drug candidate for IBD treatment.

Fabrication of the Rapid Self-Assembly Hydrogels Loaded with Luteolin: Their Structural Characteristics and Protection Effect on Ulcerative Colitis

Luteolin (LUT) is a fat-soluble flavonoid known for its strong antioxidant and anti-inflammatory properties. Nonetheless, its use in the food industry has been limited due to its low water solubility and bioavailability. In this study, hyaluronic acid, histidine, and luteolin were self-assembled to construct tubular network hydrogels (HHL) to improve the gastrointestinal stability, bioavailability, and stimulation response of LUT. As anticipated, the HHL hydrogel's mechanical strength and adhesion allow it to withstand the challenging gastrointestinal environment and effectively extend the duration of drug presence in the body. In vivo anti-inflammatory experiments showed that HHL hydrogel could successfully alleviate colitis induced by dextran sulfate sodium (DSS) in mice by reducing intestinal inflammation and restoring the integrity of the intestinal barrier. Moreover, HHL hydrogel also regulated the intestinal microorganisms of mice and promoted the production of short-chain fatty acids. The HHL hydrogel group demonstrated a notably superior treatment effect compared to the LUT group alone. The hydrogel delivery system is a novel method to improve the absorption of LUT, increasing its bioavailability and enhancing its pharmaceutical effects.

Linker-Based Pharmacophoric Design and Semisynthesis of Labdane Conjugates Active against Multi-Faceted Inflammatory Targets

Prolonged inflammation leads to the genesis of various inflammatory diseases such as atherosclerosis, cancer, inflammatory bowel disease, Alzheimer's, etc. The uncontrolled inflammatory response is characterized by the excessive release of pro-inflammatory mediators such as nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1alpha (IL-1α), and inflammatory enzymes such as cyclooxygenase-2 (COX-2). Hence, the downregulation of these inflammatory mediators is an active therapy to control aberrant inflammation and tissue damage. To address this, herein, we present the rational design and synthesis of novel phytochemical entities (NPCEs) through strategic linker-based molecular hybridization of aromatic/heteroaromatic fragments with the labdane dialdehyde, isolated from the medicinally and nutritionally significant rhizomes of the plant Curcuma amada. To validate the anti-inflammatory potential, we employed a comprehensive in vitro study assessing its inhibitory effect on the COX-2 enzyme and other inflammatory mediators, viz., NO, TNF-α, IL-6, and IL-1α, in bacterial lipopolysaccharide-stimulated macrophages, as well as in-silico molecular modeling studies targeting the inflammation regulator COX-2 enzyme. Among the synthesized novel compounds, 5f exhibited the highest anti-inflammatory potential by inhibiting the COX-2 enzyme (IC50 = 17.67 ± 0.89 μM), with a 4-fold increased activity relative to the standard drug indomethacin (IC50 = 67.16 ± 0.17 μM). 5f also significantly reduced the levels of LPS-induced NO, TNF-α, IL-6, and IL-1α, much better than the positive control. Molecular mechanistic studies revealed that 5f suppressed the expression of COX-2 and pro-inflammatory cytokine release dose-dependently, which was associated with the inhibition of the NF-κB signaling pathway. This infers that the labdane derivative 5f is a promising lead candidate as an anti-inflammatory agent to further explore its therapeutic landscape.

The single-cell modification strategies for probiotics delivery in inflammatory bowel disease: A review

Oral probiotic therapy has become an increasingly attractive method for treating various diseases, including intestinal barrier dysfunction, inflammatory bowel disease (IBD), and colorectal cancer due to its safety and convenience. However, only a few probiotics after oral gavage can survive the acidic and bile salt conditions of the gastrointestinal tract and colonize the colon to have a nutritional effect on the host. To address these challenges, encapsulation technology has been applied to protect probiotics from harsh gastrointestinal conditions, improve gut adhesion, and reduce immunogenicity. In addition, some of the functional polysaccharides are used to endow probiotics with exogenous functions as prebiotics. In this review, we systematically introduced the advancements of emerging single-cell modification strategies for probiotics in IBD applications. Additionally, we discussed the limitations and perspectives of single-cell modification strategies for probiotics. This review contributed to the development of probiotic delivery systems with higher therapeutic efficacy against colitis.

Recent advances in anti-inflammatory active components and action mechanisms of natural medicines

Inflammation is a series of reactions caused by the body's resistance to external biological stimuli. Inflammation affects the occurrence and development of many diseases. Anti-inflammatory drugs have been used widely to treat inflammatory diseases, but long-term use can cause toxic side-effects and affect human functions. As immunomodulators with long-term conditioning effects and no drug residues, natural products are being investigated increasingly for the treatment of inflammatory diseases. In this review, we focus on the inflammatory process and cellular mechanisms in the development of diseases such as inflammatory bowel disease, atherosclerosis, and coronavirus disease-2019. Also, we focus on three signaling pathways (Nuclear factor-kappa B, p38 mitogen-activated protein kinase, Janus kinase/signal transducer and activator of transcription-3) to explain the anti-inflammatory effect of natural products. In addition, we also classified common natural products based on secondary metabolites and explained the association between current bidirectional prediction progress of natural product targets and inflammatory diseases.

Discovery and Optimization of Novel hDHODH Inhibitors for the Treatment of Inflammatory Bowel Disease

As a key rate-limiting enzyme in the de novo synthesis of pyrimidine nucleotides, human dihydroorotate dehydrogenase (hDHODH) is considered a known target for the treatment of autoimmune diseases, including inflammatory bowel disease (IBD). Herein, BAY 41-2272 with a 1H-pyrazolo[3,4-b]pyridine scaffold was identified as an hDHODH inhibitor by screening an active compound library containing 5091 molecules. Further optimization led to 2-(1-(2-chloro-6-fluorobenzyl)-1H-pyrrolo[2,3-b]pyridin-3-yl)-5-cyclopropylpyrimidin-4-amine (w2), which was found to be the most promising and drug-like compound with potent inhibitory activity against hDHODH (IC50 = 173.4 nM). Compound w2 demonstrated acceptable pharmacokinetic characteristics and alleviated the severity of acute ulcerative colitis induced by dextran sulfate sodium in a dose-dependent manner. Notably, w2 exerted better therapeutic effects on ulcerative colitis than hDHODH inhibitor vidofludimus and Janus kinase (JAK) inhibitor tofacitinib. Taken together, w2 is a promising hDHODH inhibitor for the treatment of IBD and deserves to be developed as a preclinical candidate.

Treatment Effects of Natural Products on Inflammatory Bowel Disease In Vivo and Their Mechanisms: Based on Animal Experiments

Inflammatory bowel disease (IBD) is a chronic, non-specific inflammatory disease of the intestine that can be classified as ulcerative colitis (UC) and Crohn's disease (CD). Currently, the incidence of IBD is still increasing in developing countries. However, current treatments for IBD have limitations and do not fully meet the needs of patients. There is a growing demand for new, safe, and highly effective alternative drugs for IBD patients. Natural products (NPs) are used in drug development and disease treatment because of their broad biological activity, low toxicity, and low side effects. Numerous studies have shown that some NPs have strong therapeutic effects on IBD. In this paper, we first reviewed the pathogenesis of IBD as well as current therapeutic approaches and drugs. Further, we summarized the therapeutic effects of 170 different sources of NPs on IBD and generalized their modes of action and therapeutic effects. Finally, we analyzed the potential mechanisms of NPs for the treatment of IBD. The aim of our review is to provide a systematic and credible summary, thus supporting the research on NPs for the treatment of IBD and providing a theoretical basis for the development and application of NPs in drugs and functional foods.

Exposure to dechlorane 602 induces perturbation of gut immunity and microbiota in female mice

The homeostasis of gut immunity and microbiota are associated with the health of the gut. Dechlorane 602 (Dec 602) with food web magnification potential has been detected in daily food. People who were orally exposed to Dec 602 may encounter increased risk of health problems in the gut. In order to reveal the influence of short-term exposure of Dec 602 on gut immunity and microbiota, adult female C57BL/6 mice were administered orally with Dec 602 (low/high doses: 1.0/10.0 μg/kg body weight per day) for 7 days. Lymphocytes were examined by flow cytometry. Gut microbiota was measured by 16S rRNA gene sequencing. Results showed that fecal IgA was upregulated after exposure to the high dose of Dec 602, suggesting that there might be inflammation in the gut. Then, changes of immune cells in mesenteric lymph nodes and colonic lamina propria were examined. We found that exposure to the high dose of Dec 602 decreased the percentages of the anti-inflammatory T regulatory cells in mesenteric lymph nodes. In colonic lamina propria, the production of gut protective cytokine interleukin-22 by CD4⁺ T cells was decreased, and a decreased trend of interleukin-22 production was also observed in type 3 innate lymphoid cells in the high dose group. Furthermore, an altered microbiota composition toward inflammation in the gut was observed after exposure to Dec 602. Additionally, the altered microbiota correlated with changes of immune parameters, suggesting that there were interactions between influenced microbiota and immune parameters after exposure to Dec 602. Taken together, short-term exposure to Dec 602 induced gut immunity and microbiota perturbations, and this might be the mechanisms for Dec 602 to elicit inflammation in the gut.

MSX-122: Is an effective small molecule CXCR4 antagonist in cancer therapy?

Chemokines, a subgroup of cytokines along with their receptors, are involved in various biologic processes and regulation of a wide range of immune responses in different physiologic and pathologic states such as tissue repair, infection, and inflammation. C-X-C motif chemokine receptor 4 (CXCR4), a G-protein-coupled receptor (GPCR), has one identified natural ligand termed stromal-derived factor-1(SDF-1 or CXCL12). Evidence demonstrated that the ligation of SDF-1 to CXCR4 initiates several intracellular signaling pathways, regulating cell proliferation, survival, chemotaxis, migration, angiogenesis, adhesion, as well as bone marrow (BM)-resident cells homing and mobilization. Additionally, CXCR4 is expressed by tumor cells in blood malignancies and solid tumors. Therefore, CXCR4 is considered a potential therapeutic target in cancer therapy, and CXCR4 antagonists, including AMD3100, MSX-122, BPRCX807, WZ811, Motixafortide, TN14003, AMD3465, and AMD1170, have been employed in experimental and clinical studies to enhance cancer therapy. MSX-122 is a specific small-molecule antagonist of CXCR4/CXCL12 and the only orally available non-peptide CXCR4 antagonist with promising anti-cancer properties. Studies have shown that MSX-122 is particularly important in treating metastatic cancers and has great therapeutic potential. Accordingly, this review summarized the characteristics of MSX-122 and its effects on the CXCL12/CXCR4 axis as well as cancer therapy.

Polydopamine Nanoparticle-Mediated Dopaminergic Immunoregulation in Colitis

Despite immunosuppression is critical for reducing immune overactivation, existing immunosuppressive agents are largely restricted by low inhibition efficiencies and unpredictable off-target toxicities. Here, the use of the dopaminergic system is reported to suppress hyperactive immune responses in local inflamed tissues. A polydopamine nanoparticular immunosuppressant (PDNI) is synthesized to stimulate regulatory T (Treg) cells and directly inhibit T helper 1 (Th1), Th2, and Th17 cells. Moreover, PDNI can inhibit the activation of dendritic cells to upregulate the ratio of Treg/Th17, which assists the reversion of inflammatory responses. The application of dopaminergic immunoregulation is further disclosed by combining with gut microbiota modulation for treating inflammations. The combination is implemented by coating living beneficial bacteria with PDNI. Following oral delivery, coated bacteria not only suppress the hyperactive immune responses but also positively modulate the gut microbiome in mice characterized with colitis. Strikingly, the combination demonstrates enhanced treatment efficacies in comparison with clinical aminosalicylic acid in two murine models of colitis. The use of the dopaminergic system opens a window to intervene immune responses and provides a versatile platform for the development of new therapeutics for treating inflammatory diseases.

Discovery of Orally Available Retinoic Acid Receptor-Related Orphan Receptor γ-t/Dihydroorotate Dehydrogenase Dual Inhibitors for the Treatment of Refractory Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a multifactorial autoimmune disease, representing a major clinical challenge. Herein, a strategy of dual-targeting approach employing retinoic acid receptor-related orphan receptor γ-t (RORγt) and dihydroorotate dehydrogenase (DHODH) was proposed for the treatment of IBD. Dual RORγt/DHODH inhibitors are expected not only to reduce RORγt-driven Th17 cell differentiation but also to mitigate the expansion and activation of T cells, which may enhance anti-inflammatory effects. Starting from 2-aminobenzothiazole hit 1, a series of 2-aminotetrahydrobenzothiazoles were discovered as potent dual RORγt/DHODH inhibitors. Compound 14d stands out with IC₅₀ values of 0.110 μM for RORγt and of 0.297 μM for DHODH. With acceptable mouse pharmacokinetic profiles, 14d exhibited remarkable in vivo anti-inflammatory activity and dose-dependently alleviated the severity of dextran sulfate sodium (DSS)-induced acute colitis in mice. Taken together, the present study provides a novel framework for the development of therapeutic agents for the treatment of IBD.

Glycogen-based pH and redox sensitive nanoparticles with ginsenoside Rh2 for effective treatment of ulcerative colitis

The purpose of this study is to construct a pH and redox sensitive nanoparticle to effectively deliver ginsenoside Rh₂ for the treatment of ulcerative colitis (UC). Herein, glycogen was modified by urocanic acid and α-lipoic acid (α-LA) to obtain an amphiphilic polymer (LA-UaGly). Such polymer LA-UaGly could self-assemble to form nanoparticles (Blank NPs) in water with excellent stability, which could also successfully encapsulated ginsenoside Rh₂ to form Rh₂ nanoparticles (Rh₂ NPs) with encapsulation efficiency of 74.36 ± 0.34%. DLS analysis indicated Rh₂ NPs were spherical with a particle size of 128.9 ± 0.3 nm. As expected, Rh₂ NPs exhibited typical pH and redox dual response release behaviour as well as the excellent in vivo safety. In vitro tests showed that Rh₂ NPs could effectively internalize and release Rh₂ into RAW264.7 cells, and protect cells from apoptosis (p < 0.05). More interestingly, Rh₂ NPs exhibited strong anti-inflammatory activity via significantly inhibiting the overproduction of nitric oxide (NO) and inflammatory cytokines (TNF-α, IL-1β and IL-6) (p < 0.05). In vivo experiments suggested that Rh₂ NPs significantly ameliorated the weight loss, colon length, disease activity index (DAI) score, and myeloperoxidase (MPO) activity in mice caused by dextran sulfate sodium salt (DSS) (p < 0.05). Simultaneously, pathological analysis proved that Rh₂ NPs could significantly reduce histological damage and inflammatory infiltration in mice. Rh₂ NPs could also effectively regulate the intestinal flora of mice by improving the species uniformity and abundance of the intestinal flora of mice and restoring the species diversity of the intestinal flora. In addition, both in vivo and in vitro experiments proved that Rh₂ NPs had stronger anti-inflammatory activity than Rh₂. This study provides a promising strategy for the effective treatment of UC.

Sesquiterpene Lactones from Sigesbeckia glabrescens Possessing Potent Anti-inflammatory Activity by Directly Binding to IKKα/β

Chromatographic fractionation of Sigesbeckia glabrescens led to the identification of 10 new sesquiterpene lactones, named siegesbeckialides I-O (1-7) and glabrescones A-C (8-10), along with 14 known analogues. An anti-inflammatory activity assay showed that siegesbeckialide I (1) most potently inhibited LPS-induced NO production in RAW264.7 murine macrophages. Furthermore, siegesbeckialide I suppressed the protein expression of iNOS and COX2, as well as the release of PGE₂, IL-1β, IL-6, and TNF-α in LPS-stimulated RAW264.7 cells. Mechanistically, siegesbeckialide I directly binds to inhibitors of IKKα/β and suppresses their phosphorylation. This leads to the inhibition of IKKα/β-mediated phosphorylation and degradation of inhibitor α of NF-κB (IκBα), as well as the activation of NF-κB signaling.

Target-Based Small Molecule Drug Discovery Towards Novel Therapeutics for Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a class of severe and chronic diseases of the gastrointestinal (GI) tract with recurrent symptoms and significant morbidity. Long-term persistence of chronic inflammation in IBD is a major contributing factor to neoplastic transformation and the development of colitis-associated colorectal cancer. Conversely, persistence of transmural inflammation in CD is associated with formation of fibrosing strictures, resulting in substantial morbidity. The recent introduction of biological response modifiers as IBD therapies, such as antibodies neutralizing tumor necrosis factor (TNF)-α, have replaced nonselective anti-inflammatory corticosteroids in disease management. However, a large proportion (~40%) of patients with the treatment of anti-TNF-α antibodies are discontinued or withdrawn from therapy because of (1) primary nonresponse, (2) secondary loss of response, (3) opportunistic infection, or (4) onset of cancer. Therefore, the development of novel and effective therapeutics targeting specific signaling pathways in the pathogenesis of IBD is urgently needed. In this comprehensive review, we summarize the recent advances in drug discovery of new small molecules in preclinical or clinical development for treating IBD that target biologically relevant pathways in mucosal inflammation. These include intracellular enzymes (Janus kinases, receptor interacting protein, phosphodiesterase 4, IκB kinase), integrins, G protein-coupled receptors (S1P, CCR9, CXCR4, CB2) and inflammasome mediators (NLRP3), etc. We will also discuss emerging evidence of a distinct mechanism of action, bromodomain-containing protein 4, an epigenetic regulator of pathways involved in the activation, communication, and trafficking of immune cells. We highlight their chemotypes, mode of actions, structure-activity relationships, characterizations, and their in vitro/in vivo activities and therapeutic potential. The perspectives on the relevant challenges, new opportunities, and future directions in this field are also discussed.

Discovery of Novel Pterostilbene-Based Derivatives as Potent and Orally Active NLRP3 Inflammasome Inhibitors with Inflammatory Activity for Colitis

Studies have shown that the abnormal activation of the NLRP3 inflammasome is involved in a variety of inflammatory-based diseases. In this study, a high content screening model targeting the activation of inflammasome was first established and pterostilbene was discovered as the active scaffold. Based on this finding, total of 50 pterostilbene derivatives were then designed and synthesized. Among them, compound 47 was found to be the best one for inhibiting cell pyroptosis [inhibitory rate (IR) = 73.09% at 10 μM], showing low toxicity and high efficiency [against interleukin-1β (IL-1β): half-maximal inhibitory concentration (IC50) = 0.56 μM]. Further studies showed that compound 47 affected the assembly of the NLRP3 inflammasomes by targeting NLRP3. The in vivo biological activity showed that this compound significantly alleviated dextran sodium sulfate (DSS)-induced colitis in mice. In general, our study provided a novel lead compound directly targeting the NLRP3 protein, which is worthy of further research and structural optimization.

Colon-targeted delivery of tacrolimus using pH-responsive polymeric nanoparticles for murine colitis therapy

The present study aimed at constructing an oral nanoparticle delivery system loaded with tacrolimus (FK506) for effective treatment of inflammatory bowel disease. A FK506/HP-β-CD inclusion compound was prepared by grinding to increase drug solubility. To address the side- effects in non-target organs and systemic toxicity of FK506, pH-responsive Eudragit S100 (ES100) and hyaluronic acid (HA) with high affinity to CD44 receptor were adsorbed onto the surface of chitosan (CS) nanoparticles loaded with FK506/HP-β-CD through electrostatic interactions to obtain FK506@ES100/HA/CS/HP-β-CD nanoparticles (FK506@EHCh NPs). Caco-2 cells and Raw 264.7 macrophages were used to confirm the lack of cytotoxicity and good uptake ability of the newly generated nanoparticles. FK506@EHCh NPs significantly suppressed secretion of TNF-α, IL-1β and IL-6 by LPS-activated Raw 264.7 macrophages. A dextran sodium sulfate (DSS)-induced inflammatory bowel disease (IBD) murine model was established to further confirm the colon targeting and in vivo efficacy of oral IR-775@EHCh NPs. Based on the collective results, we conclude that packaging FK506 into active targeting nanocarriers sensitive to pH facilitates concentration of the drug within the sites of intestinal inflammation and improves the drug levels in target tissues, thus avoiding systemic side-effects and improving efficacy. In view of the promising results obtained in this study, the potential of EHCh nanoparticles for drug delivery and targeted treatment of inflammatory bowel disease warrants further investigation.

Polyphenols from food by-products: An alternative or complementary therapy to IBD conventional treatments

Inflammatory bowel diseases (IBD) are illnesses characterized by chronic intestinal inflammation and microbial dysbiosis that have emerged as a public health challenge worldwide. It comprises two main conditions: Crohn's disease and ulcerative colitis. Currently, conventional therapy to treat IBD are not free from side effects, such as liver and kidney toxicity, drug resistance, and allergic reactions. In view of this, there is growing research for alternative and complementary therapies that, in addition to acting in the prevention or the control of the disease, do not compromise the quality of life and health of individuals. In this sense, a growing body of evidence has confirmed the benefits of natural phenolic compounds in intestinal health. Phenolic compounds or polyphenols are molecules widely distributed throughout the plant kingdom (flowers, vegetables, leaves, and fruits), including plant materials remaining of the handling and food industrial processing, referred to in the scientific literature as by-products, food waste, or bagasse. Since by-products are low-cost, abundant, easily accessible, safe, and rich in bioactive compounds, it becomes an exciting option to extract, concentrate or isolate phenolic compounds to be posteriorly applied in the therapeutic approach of IBD. In this article, we have reviewed the main phenolic compounds present in various plants and by-products that have shown beneficial and/or promising effects in experimental pre-clinical, clinical, and in vitro research with IBD. In addition, we have mentioned and suggested several plants and by-products originated and produced in Latin America that could be part of future research as good sources of specific phenolic compounds to be applied in the prevention and development of alternative treatments for IBD. This review may offer a valuable reference for studies related to IBD administering phenolic compounds from natural, cheap, and easily accessible raw and undervalued materials.