Indigodole E from Strobilanthes cusia exhibits anti-IL-17A effect.

One new indazole alkaloid, indigodole E (1), was isolated from a traditional Chinese medicine Qing Dai prepared from the aerial parts of Strobilanthes cusia. The structure of 1 was elucidated by NMR, MS, UV, and IR spectra as well as optical rotation. Additionally, compound 1 could obviously inhibit not only IL-17A protein production at concentrations from 1.25 to 2.5 µg/mL, but also IL-17 gene expression at concentrations from 5.0 to 10.0 µg/mL without cytotoxicity toward Th17 and Jukat cells, respectively. Overall, indazole analogue 1 could be the anti-IL 17 A contributor of Qing Dai in this investigation.

Indigo enhances wound healing activity of Caco-2 cells via activation of the aryl hydrocarbon receptor.

Indigo Naturalis, also known as Qing Dai (QD) is a compound obtained from Indigofera tinctoria, Isatis tinctoria, and Polygonum tinctoria and is known to ameliorate refractory ulcerative colitis (UC) by an unknown mechanism. QD maintains both homeostasis and the integrity of colon epithelia in mice that have experimentally induced colitis. The primary component of QD, indigo, comprises 42.4% of the compound. Indigo efficiently suppresses rectal bleeding and reduces the erosion of the colon epithelium, whereas it does not reduce weight loss or increase survival in a certain condition. Indigo is a ligand of the aryl hydrocarbon receptor (AhR), which is involved in the anti-colitis activity of QD. Here we investigate the effects of indigo on wound (erosion) closure in colon epithelial cells. Oral administration of indigo induced expression of Cytochrome P450 1A1 (Cyp1a1) in the colon but not in the liver, suggesting that indigo stimulates AhR from the luminal side of the colon. The erosion-closure activity tested in the scratch assays using Caco-2 cells was accelerated by addition of QD and indigo to the culture medium. QD and indigo also induced nuclear localization of AhR and expression of CYP1A1 in the Caco-2 cells. Acceleration of scratch wound closure was abolished by addition of the AhR-antagonist CH223191. Cell proliferation and actin polymerization were also shown to contribute to erosion closure. The results suggest that indigo exerts its erosion-healing effects by increasing proliferation and migration of colon epithelial cells via activation of AhR in intestinal epithelia.

Aryl hydrocarbon receptor is essential for the pathogenesis of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a devastating disease characterized by arteriopathy in the small to medium-sized distal pulmonary arteries, often accompanied by infiltration of inflammatory cells. Aryl hydrocarbon receptor (AHR), a nuclear receptor/transcription factor, detoxifies xenobiotics and regulates the differentiation and function of various immune cells. However, the role of AHR in the pathogenesis of PAH is largely unknown. Here, we explore the role of AHR in the pathogenesis of PAH. AHR agonistic activity in serum was significantly higher in PAH patients than in healthy volunteers and was associated with poor prognosis of PAH. Sprague-Dawley rats treated with the potent endogenous AHR agonist, 6-formylindolo[3,2-b]carbazole, in combination with hypoxia develop severe pulmonary hypertension (PH) with plexiform-like lesions, whereas Sprague-Dawley rats treated with the potent vascular endothelial growth factor receptor 2 inhibitors did not. Ahr-knockout (Ahr-/- ) rats generated using the CRISPR/Cas9 system did not develop PH in the SU5416/hypoxia model. A diet containing Qing-Dai, a Chinese herbal drug, in combination with hypoxia led to development of PH in Ahr+/+ rats, but not in Ahr-/- rats. RNA-seq analysis, chromatin immunoprecipitation (ChIP)-seq analysis, immunohistochemical analysis, and bone marrow transplantation experiments show that activation of several inflammatory signaling pathways was up-regulated in endothelial cells and peripheral blood mononuclear cells, which led to infiltration of CD4+ IL-21+ T cells and MRC1+ macrophages into vascular lesions in an AHR-dependent manner. Taken together, AHR plays crucial roles in the development and progression of PAH, and the AHR-signaling pathway represents a promising therapeutic target for PAH.

IL-17A inhibitions of indole alkaloids from traditional Chinese medicine Qing Dai.

ETHNOPHARMACOLOGICAL RELEVANCE: Qing Dai, a famous traditional Chinese medicine (TCM), is prepared by a traditional fermentation process with the aerial part of Strobilanthes cusia. Currently, this TCM could treat various clinical inflammatory diseases, such as ulcerative colitis and psoriasis, however, the bioactive components of Qing Dai are unknown clearly. AIM OF THE STUDY: To isolate and identify the anti-IL-17A components of Qing Dai. MATERIALS AND METHODS: Silica, RP-18 gels, and size exclusion resin were used for column chromatography to isolate the pure compounds. The structures of isolates were elucidated by NMR, MS, UV, IR spectra, and optical rotation. IL-17A protein and gene expressions were also evaluated in the Th17 cell model and luciferase reporter assay, respectively. RESULTS: Two indole alkaloids, including one new indigodole D and cephalandole B, were isolated from Qing Dai. Indigodole D could inhibit IL-17A protein production during the Th17 polarization (EC50: 2.16 µg/mL) or after the polarization (EC50: 5.99 µg/mL) without cytotoxicity toward Th17 cells. Cephalandole B did not inhibit the IL-17A protein secretion. Nevertheless, both isolates notably inhibited IL-17A gene expression, especially cephalandole B, in a dose-dependent manner in Jukat cells with IL-17A luciferase reporter. CONCLUSIONS: Indole alkaloids, indigodoles A, C, D, tryptanthrin, and indirubin could contribute to anti-IL 17A properties of Qing Dai. The possible biogenetic mechanisms of above-mentioned indoles were also speculated in this investigation for further promising anti-IL-17 lead drugs development.

Comparison of the anti-colitis activities of Qing Dai/Indigo Naturalis constituents in mice.

Qing Dai/Indigo Naturalis (QD) has been shown to ameliorate ulcerative colitis (UC) in clinical trials; however, its mechanism remains elusive. This study investigates the effects of QD on murine dextran sulfate sodium salt-induced colitis. Oral administration of QD protected the animals from colitis as manifested by weight loss, diarrhea, and rectal bleeding. QD was distinguishingly more effective than 5-aminosalicylate. Focused microarray analysis of genes expressed in the distal colon suggested that QD influences the inflammatory pathway. Anti-inflammatory activity of QD was confirmed by the suppression of nitric oxide (NO) production in response to interleukin-1ß in cultured hepatocytes. Some of the constituents in QD, such as tryptanthrin (TRYP) and indigo, suppressed NO production. TRYP maintained body weight but did not inhibit bleeding. Indigo, on the other hand, partially ameliorated bleeding, but did not maintain body weight. The combination of TRYP and indigo did not show additive ameliorating activity. The methanol extract of QD showed an anti-colitis activity like that of TRYP. In contrast, the methanol-insoluble QD fraction moderately ameliorated diarrhea and bleeding. Combining these two fractions resulted in full anti-colitis activity. Further clarification of the active constituents will help in the discovery of a safe and potent prescription for UC.

Development of an Indigo Naturalis Suppository for Topical Induction Therapy in Patients with Ulcerative Colitis.

BACKGROUND: Indigo naturalis (IN) consists of ligands for the aryl hydrocarbon receptor and exhibits anti-inflammatory effects. Previously, we demonstrated that an 8-week treatment with oral IN is effective in inducing a clinical response in patients with ulcerative colitis (UC). Some UC patients with proctitis are refractory to topical mesalamine or corticosteroids and therefore require an alternative topical treatment. OBJECTIVES: We aimed to prospectively evaluate the safety and efficacy of IN suppositories in UC patients. METHOD: We performed an open-label, single-center, prospective pilot study from February 2018 to October 2018. A total of 10 patients with active UC, who had moderate to severe inflammation from the rectum to the sigmoid colon, were enrolled. The patients received a daily dose of 50 mg IN suppository for 4 weeks. The primary endpoint was safety at week 4. RESULTS: Although 1 patient experienced anal pain, no serious adverse events were observed. At week 4, the rates of clinical remission and mucosal healing were 30 and 40%, respectively. Mayo rectal bleeding subscores significantly improved after treatment (1.80 ± 0.13 vs. 0.90 ± 0.28; p = 0.009). Approximately 80% of the patients with a baseline Mayo endoscopic subscore in the rectum (r-MES) of 2 achieved mucosal healing, but those with a baseline r-MES of 3 did not. CONCLUSIONS: We found that 4 weeks of IN suppository can be tolerated by UC patients, but its efficacy was limited by the severity of the disease. Further investigation will be needed in order to confirm the optimum dose of IN suppository for patients with UC.

Short-term and long-term outcomes of indigo naturalis treatment for inflammatory bowel disease.

BACKGROUND AND AIM: Indigo naturalis (IN) is a traditional Chinese herbal medicine reported to be effective in inducing remission in ulcerative colitis (UC). We conducted a retrospective observational study to investigate the efficacy and safety of IN for induction and maintenance therapy in patients with inflammatory bowel disease. METHODS: Data were collected from the electric medical records of patients with inflammatory bowel disease who had started IN treatment between March 2015 and April 2017 at Kyushu University Hospital. Clinical response and remission rates were assessed based on the clinical activity index determined by Rachmilewitz index or Crohn's disease (CD) activity index. Cumulative IN continuation rates were estimated using the Kaplan-Meier method. Overall adverse events (AEs) during follow-up were also analyzed. RESULTS: Seventeen UC patients and eight CD patients were enrolled. Clinical response and remission rates at week 8 were 94.1% and 88.2% in UC patients and 37.5% and 25.0% in CD patients, respectively. Clinical remission rates, as assessed through non-responders imputation analyses at weeks 52 and 104, were 76.4% and 70.4% in UC patients and 25.0% and 25.0% in CD patients, respectively. Ten patients (40%) experienced AEs during follow-up. Three patients (12%) experienced severe AEs, including acute colitis requiring hospitalization in two patients and acute colitis with intussusception requiring surgery in one patient. CONCLUSIONS: Indigo naturalis showed favorable therapeutic efficacy in UC, whereas its therapeutic efficacy in CD appeared to be modest. The risk of severe AEs should be recognized for IN treatment.

Efficacy of Indigo Naturalis Therapy for Ulcerative Colitis: A Case Series.

Objective Indigo naturalis (IN) is a traditional Chinese medicine that has recently been reported to be effective for ulcerative colitis (UC). The aim of this study was to evaluate the efficacy and safety of IN. Methods We performed a retrospective observational study for 14 patients with UC treated with IN from October 2015 to December 2016. Results After 8 weeks of oral administration of IN, the partial Mayo score decreased from 4 (2-5) to 1.5 (0-4) [median, interquartile range (IQR), p=0.015]. Among 10 active UC patients, 5 (50%) showed a clinical response, and 4 (40%) achieved clinical remission. Serial changes of endoscopic activity were evaluated in nine patients using the Mayo endoscopic subscore (MES), Rachmilewitz endoscopic index (REI), and UC endoscopy index of severity (UCEIS). The MES decreased from 2 (2-3) to 1 (1-2) [median (IQR), p=0.005], the REI decreased from 7 (5.5-11) to 3 (1-7) [median (IQR), p=0.008], and the UCEIS decreased from 3 (3-4.5) to 1 (0.5-3.5) [median (IQR), p=0.039]. One patient developed acute right-sided colitis with wall thickening and edematous change, and the remaining 13 showed no adverse events. Conclusion We conclude that IN is effective for patients with UC as a therapy for inducing remission.

Treatment with indigo naturalis for inflammatory bowel disease and other immune diseases.

Indigo naturalis (IN) is a herbal medicine extracted from leaves and stems of plants and is a component of crude drugs used in China. Recently, IN was reported to be effective for treating (UC) and psoriasis. The mechanisms of IN for UC is not clear, but aryl hydrocarbon receptor ligand, the active components of IN, can promote mucosal healing by inducing the production of interleukin-22 from type-3 innate lymphocytes cells. Although IN is effective even for refractory cases, critical adverse effects including IN-induced colitis and pulmonary arterial hypertension should be concerned. Due to adverse effects of IN, topical treatment of IN is useful for distal UC as well as psoriasis to secure patients' safeties. Many refractory patients may be helped by IN if it becomes available in appropriate forms for clinical practice. In the near future, the mechanism that underlies the adverse effects of IN needs to be determined, and extraction of active ingredients with fewer side effects, investigated.

Chinese herbal medicine Qing-Dai-induced pulmonary arterial hypertension in a patient with ulcerative colitis: A case report and experimental investigation.

A recent case report described a case of pulmonary arterial hypertension (PAH) associated with use of the Chinese herbal medicine Qing-Dai; however, the clinical course and possible mechanisms have not been characterized. We present the case of a man with ulcerative colitis who was diagnosed with idiopathic PAH. After initiating oral beraprost therapy, the patient showed significant hemodynamic improvements and an unusual course of clinical recovery. In 2016, the Japanese Ministry of Health, Labour, and Welfare issued a warning regarding the possible side effects of Qing-Dai. We learned that our patient had been taking self-purchased Qing-Dai for 2 years. Therefore, we performed an experimental study and determined that Qing-Dai may cause PAH through a mechanism involving nitric oxide synthase inhibition and pulmonary artery endothelial dysfunction.

Indole alkaloids indigodoles A-C from aerial parts of Strobilanthes cusia in the traditional Chinese medicine Qing Dai have anti-IL-17 properties.

Qing Dai (Naturalis Indigo) is a traditional Chinese medicine (TCM) used as a topical agent in moderate psoriasis, targeting interleukin-17 (IL-17). In this study, it was prepared from the aerial parts of Strobilanthes cusia. Three undescribed indole alkaloid derivatives, indigodoles A-C, along with seven known compounds were isolated from this preparation of Qing Dai and their structures were elucidated from spectroscopic data, including NMR, MS, UV, IR, optical rotation, and CD. As well, most compounds were tested against IL-17. Indigodole C and tryptanthrin could significantly inhibit IL-17 production of Th17 cells. In addition, indigodole A and indirubin showed notably anti-IL-17 gene expression in dose-dependent effects without cytotoxicities toward Th17 and Jurkat cells, respectively. Overall, our studies indicate that the aforementioned indole alkaloids could contribute to anti-IL 17 properties of Qing Dai.

The preventive effect of Qing Dai on bisphosphonate-induced gastric cellular injuries.

The Chinese herbal medicine Qing Dai has been traditionally used for the treatment of various inflammatory diseases. We previously reported that reactive oxygen species play an important role in bisphosphonate-induced gastrointestinal injuries and that Qing Dai improved ulcerative colitis by scavenging reactive oxygen species. In this study, we investigated whether Qing Dai prevented bisphosphonate-induced gastric cellular injuries. Risedronate (a bisphosphonate) was added to rat gastric mucosal cells. Risedronate-induced cellular injury, cellular lipid peroxidation, mitochondrial membrane potential, and reactive oxygen species production in rat gastric mucosal cells were examined via viable cell counting, specific fluorescent indicators, and electron spin resonance. Pretreatment with Qing Dai attenuated the fluorescence intensity of diphenyl-1-pyrenylphosphine and MitoSox as well as the signal intensities of electron spin resonance. Cell viability improved from 20% to 80% by pretreatment with Qing Dai. Thus, Qing Dai prevented this injury by suppressing mitochondrial reactive oxygen species production, which is the main cause of cellular lipid peroxidation. Qing Dai also maintained mitochondrial potential, reducing reactive oxygen species production. We conclude that Qing Dai has protective effects on bisphosphonate-induced gastrointestinal injury and thus has the potential for clinical application.

Development of Pulmonary Arterial Hypertension in a Patient Treated with Qing-Dai (Chinese Herbal Medicine).

Pulmonary arterial hypertension (PAH) is a rare, devastating disease, characterized by elevated pulmonary arterial pressure due to pulmonary microvascular obstruction, which can result in heart failure and death. PAH can be associated with exposure to certain drugs or toxins. We herein report a case in which PAH developed in a patient with refractory ulcerative colitis during treatment with "Qing-Dai," a Chinese herbal medicine. The patient's PAH improved after the discontinuation of Qing-Dai.

Indirubin, a Constituent of the Chinese Herbal Medicine Qing-Dai, Attenuates Dextran Sulfate Sodium-induced Murine Colitis.

BACKGROUND: Indirubin, a constituent of the Chinese herbal medicine "Qing-Dai," has anti-cancer and anti-inflammatory activities. We aimed to evaluate the efficacy of indirubin for ameliorating colonic inflammation in a mouse model of inflammatory bowel disease. METHODS: Mice with dextran sulfate sodium (DSS)-induced acute and chronic colitis were treated with indirubin in their diet. Clinical and histologic changes were evaluated. In addition, colon levels of interleukin-6, a critical pro-inflammatory mediator, was detected by enzyme-linked immunosorbent assay. RESULTS: In the model of acute colitis, indirubin treatment improved the loss of body weight. Histology of colonic tissue revealed that indirubin treatment improved the histology grading of colitis (P = 0.02), the extent of submucosal fibrosis (P = 0.018), the number of mucosal toluidine blue-positive cells (P = 0.004) and colon length (P = 0.01). In the model of chronic colitis, indirubin treatment had no significant effect on pathologic findings except for colon length (P = 0.003). However, indirubin administration significantly reduced colon levels of interleukin-6 in the chronic-colitis model (P = 0.001). CONCLUSION: Our study clearly showed that oral intake of indirubin can improve murine DSS-induced colitis (which mimics human inflammatory bowel disease).

Colitis with wall thickening and edematous changes during oral administration of the powdered form of Qing-dai in patients with ulcerative colitis: a report of two cases.

Orally administered Qing-dai, called indigo naturalis in Latin, is reportedly useful for the treatment of ulcerative colitis. We herein describe two patients with ulcerative colitis who developed colitis with wall thickening and edematous changes during oral administration of the powdered form of Qing-dai. In Case 1, a 35-year-old man developed colitis similar to ischemic colitis with bloody stool that recurred each time he ingested Qing-dai. He had no signs of recurrence upon withdrawal of Qing-dai. In Case 2, a 43-year-old woman underwent ileocecal resection for treatment of an intussusception 2 months after beginning oral administration of Qing-dai. Edema and congestion but no ulceration were present in the mucosa of the resected specimen. Both patients exhibited abdominal pain with bloody diarrhea, and abdominal computed tomography showed marked wall edema affecting an extensive portion of the large bowel.

Efficacy of Indigo Naturalis in a Multicenter Randomized Controlled Trial of Patients With Ulcerative Colitis.

BACKGROUND & AIMS: Indigo naturalis (IN) is a traditional Chinese medicine that contains ligands for the aryl hydrocarbon receptor and promotes regeneration of the mucosa by inducing production of interleukin 22. IN might induce mucosal healing in patients with ulcerative colitis (UC). We performed a randomized controlled trial to investigate the safety and efficacy of IN in patients with UC. METHODS: We performed a multicenter, double-blind trial evaluating the safety of 86 patients in Japan with active UC (Mayo scores of 6 or more), enrolled from March 30 through December 27, 2016. Patients were randomly assigned to groups and given a daily dose of 0.5, 1.0, or 2.0 g IN or placebo (1:1:1:1 ratio) for 8 weeks. The primary endpoint was the rate of clinical response at week 8, defined as a 3-point decrease in the Mayo score and a decrease of at least 30% from baseline, with a decrease of at least 1 point for the rectal bleeding subscore or absolute rectal bleeding score of 0-1. The main secondary endpoint was the rate of clinical remission at week 8, defined as a Mayo score or ≤2 and no subscores with a value >1. Mucosal healing was also assessed at week 8. RESULTS: The trial was terminated because of an external reason: a report of pulmonary arterial hypertension in a patient who used self-purchased IN for 6 months. In the intent-to-treat analysis, we observed a significant, dose-dependent linear trend in proportions of patients with clinical responses (13.6% with a clinical response to placebo; 69.6% to 0.5 g IN; 75.0% to 1.0 g IN; and 81.0% to 2.0 g IN) (Cochran-Armitage trend test P < .0001 compared with placebo). Proportions of patients in clinical remission at week 8 were significantly higher in the 1.0 g IN group (55.0%, P = .0004) and the 2.0 g IN group (38.1%, (P = .0093) than in the placebo group (4.5%). Proportions of patients with mucosal healing were 13.6% in the placebo group, 56.5% in the 0.5 g IN group, 60.0% in the 1.0 g IN group, and 47.6% in the 2.0 g IN group (P = .0278 compared with placebo). Although mild liver dysfunction was observed in 10 patients who received IN, no serious adverse events were observed. CONCLUSIONS: In a randomized, placebo-controlled trial, we found 8 weeks of IN (0.5-2.0 g per day) to be effective in inducing a clinical response in patients with UC. However, IN should not yet be used because of the potential for adverse effects, including pulmonary arterial hypertension. Clinical Trials Registry no: UMIN000021439 (http://www.umin.ac.jp/ctr/).

Indigo Naturalis Ameliorates Oxazolone-Induced Dermatitis but Aggravates Colitis by Changing the Composition of Gut Microflora.

BACKGROUND: Indigo naturalis (IND) is an herbal medicine that has been used as an anti-inflammatory agent to treat diseases including dermatitis and inflammatory bowel disease in China. However, the mechanism by which IND exerts its immunomodulatory effect is not well understood. METHODS: A murine model of dermatitis and inflammatory bowel disease, both induced by oxazolone (OXA), was treated with IND. The severity of dermatitis was evaluated based on ear thickness measurements and histological scoring. The severity of colitis was evaluated by measuring body weight, histological scoring, and endoscopic scoring. The expression of inflammatory cytokines in ear and colon tissue was evaluated using real-time PCR. 16S rRNA DNA sequencing of feces from OXA-induced colitis mice was performed before and after IND treatment. The effects of IND on OXA-induced colitis were also evaluated after depleting the gut flora with antibiotics to test whether alteration of the gut flora by IND influenced the course of intestinal inflammation in this model. RESULTS: IND treatment ameliorated OXA dermatitis with a reduction in IL-4 and eosinophil recruitment. However, OXA colitis was significantly aggravated in spite of a reduction in intestinal IL-13, a pivotal cytokine in the induction of the colitis. It was found that IND dramatically altered the gut flora and IND no longer exacerbated colitis when colitis was induced after gut flora depletion. CONCLUSIONS: Our data suggest that IND could modify the inflammatory immune response in multiple ways, either directly (i.e., modification of the allergic immune cell activity) or indirectly (i.e., alteration of commensal compositions).

Qing Dai attenuates nonsteroidal anti-inflammatory drug-induced mitochondrial reactive oxygen species in gastrointestinal epithelial cells.

Treatments with nonsteroidal anti-inflammatory drugs (NSAIDs) have increased the number of patients with gastrointestinal complications. Qing Dai has been traditionally used in Chinese herbal medicine for various inflammatory diseases such as ulcerative colitis. We previously reported that Qing Dai suppressed inflammations by scavenging reactive oxygen species (ROS) in ulcerative colitis patients. Thus, Qing Dai can attenuate the production of ROS, which play an important role in NSAID-induced gastrointestinal injuries. In this study, we aimed to elucidate whether Qing Dai decreased mitochondrial ROS production in NSAID-treated gastrointestinal cells by examining cellular injury, mitochondrial membrane potentials, and ROS production with specific fluorescent indicators. We also performed electron paramagnetic resonance measurement in isolated mitochondria with a spin-trapping reagent (CYPMPO or DMPO). Treatments with indomethacin and aspirin induced cellular injury and mitochondrial impairment in the gastrointestinal cells. Under these conditions, mitochondrial alterations were observed on electron microscopy. Qing Dai prevented these complications by suppressing ROS production in gastrointestinal cells. These results indicate that Qing Dai attenuated the ROS production from the NSAID-induced mitochondrial alteration in the gastrointestinal epithelial cells. Qing Dai treatment may be considered effective for the prevention NSAID-induced gastrointestinal injury.

Therapeutic efficacy of the Qing Dai in patients with intractable ulcerative colitis.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that may become intractable when treated with conventional medications such as aminosalicylates, corticosteroids, and azathioprine. The herbal medicine Qing Dai has traditionally been used in Chinese medicine to treat UC patients, but there is a lack of published data on the efficacy of Qing Dai in UC treatment. We report several cases of patients with intractable UC who take Qing Dai in a retrospective observational study. Furthermore, we explore the mechanisms of action of Qing Dai. Nine patients with active UC who received conventional medications but wished to receive Qing Dai as an alternative medication were included in our analysis. The UC severity level was determined based on the clinical activity index (CAI). Additionally, 5 of the 9 patients were endoscopically evaluated according to the Matts grading system. Each patient received 2 g/d of Qing Dai orally and continued taking other medications for UC as prescribed. Electron spin resonance was applied to explore the mechanisms of action of Qing Dai. After 4 mo of treatment with Qing Dai, the CAI score decreased from 8.3 ± 2.4 to 2.4 ± 3.4 (mean ± SD; P < 0.001). Similarly, the endoscopic Matts grade decreased from 3.4 ± 0.5 to 2.2 ± 0.8 (P = 0.02). Six of 7 patients who were on prednisolone upon enrollment in the study were able to discontinue this corticosteroid. Electron spin resonance revealed that Qing Dai possesses strong hydroxyl radical scavenging activity. Qing Dai showed significant clinical and endoscopic efficacy in patients who failed to respond to conventional medications. Scavenging of hydroxyl radicals appears to be a potential mechanism through which Qing Dai acts, but the significance of the scavenging ability of Qing Dai with respect to the anti-inflammatory effect in UC patients warrants further investigation.