1 Introduction

Ulcerative colitis (UC) is a common non-specific chronic protracting and relapsing inflammatory disease, which relates the large intestine mucosa and submucosa, and its most important clinical manifestations are characterized by diarrhoea, abdominal pain, mucus pus, and blood in the stool [1, 2]. And with its recurrent ymptoms, long-time treatment and significant morbidity [3, 4]. the effective treatment of UC is becoming more and more important.

At present, the precise cause of UC is unclear, and it may related to genetics, environment, leucocyte recruitment, disruption of colon barrier function and mucosal immune response [5]. The clinical treatment is mainly focus on medicine therapy, interleukin antagonist, immunosuppressive agents, corticosteroids and salicylates. Through previous studies, with various side effects in the treatment, it is necessary to explore more safe and effective ways to treat UC [6].

Traditional Chinese medicine (TCM) has developed for thousands of years, it is one of the greatest treasures of Chinese culture, and it is the crystallization of medical wisdom and experience of the Chinese nation which accumulated from large numbers of theories and rich clinical experience [7]. According to the theory of TCM, UC belongs to the category of dysentery, diarrhoea, and hematochezia, etc. TCM symptoms of UC include mainly types of dampness-heat in large intestine, excessive heat-toxin, dampness stagnancy due to spleen deficiency, Yang deficiency of spleen and kidney, cold-heat complicated symptom and so on, and the chief symptom of UC is dampness-heat in large intestine [8]. On the one hand, when evil heat attacks blood vessels, it will cause abnormal blood circulation, then it lead to force the blood to act recklessly, therefore, the patients with UC of dampness-heat symptom characterized by bloody stool. On the other hand, “Su Wen” has recorded that “Predominant dampness causing diarrhea”, and “Yizong Bidu” said “No diarrhea without dampness”. The dampness is heavy, turbid, sticky and stagnant, and it tends to move downward, so the intestinal symptoms of UC patients occurs repeatedly with protracted process [2.

Table 1 The information of 46 candidate compounds in Ermiaosan
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Fig. 1
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The result of drug-compound-target network (Light blue ellipses represent the drugs of Ermiaosan, fuchsia diamonds represent compounds of Ermiaosan, yellow round rectangles represent potential targets of Ermiaosan)

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Table 2 Top 3 candidate compounds of Ermiaosan
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Fig. 2
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Venny diagram of Ermiaosan (medicine gene) and ulcerative colitis (disease gene) intersection targets. 408 overlap** targets represent the candidate targets of Ermiaosan against ulcerative colitis

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3.2 Network of intersection targets

3.2.1 PPI network of targets

To get further understanding about the interaction of these 408 overlap** targets, the STRING tool was applied to construct PPI network of the relationships of herb compounds-disease-tergets for these targets. We set the confidence score > 0.7, the analysis of PPI network shown that there were 408 nodes and the number of edges was 9421, the average node degree was 46.2, and the average local clustering coefficient was 0.534 ( As shown in Fig. 3).

Fig. 3
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Protein–protein interaction networks of Ermiaosan and ulcerative colitis

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3.2.2 Result of cytoscape network of targets and the hub genes

We used Cytoscape3.8.2 software to visualise the combined score of the STRING database of Ermiaosan and ulcerative colitis ( As shown in Fig. 4), and then we set the node size and color to map the degree value and score value to construct drug-target interaction of the drug and disease, it contained 411 nodes and the number of edges was 951, the average node degree was 92.6, with the methods Degree greater than fourfold above the average was set to select core genes by cytoHubba plugin, these top 7 targets were the key targets of Ermiaosan against ulcerative colitis, the darker the color, the higher the correlation. ( As shown in Fig. 5 and Table 3).

Fig. 4
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Drug-disease-tergets interaction of Ermiaosan and ulcerative colitis. (Red diamonds represent ulcerative colitis, light blue ellipses represent the drug of Ermiaosan, grass green round rectangles represent potential common targets of Ermiaosan and ulcerative colitis.)

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Fig. 5
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Top 7 key targets in PPI network

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Table 3 Key targets in PPI network that are Degree greater than fourfold above the average (Top 7)
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3.3 The results of enrichment analysis

The multiple potential mechanisms of Ermiaosan against ulcerative colitis through Bioinformatic analysis which was performed using the OECloud tools at https://cloud.oebiotech.cn., with the default option was P value < 0.05. And the results of top 10 main items of each categories of GO terms were: protein phosphorylation, positive regulation of cell proliferation, positive regulation of angiogenesis, inflammatory response, vascular endothelial growth factor receptor signaling pathway, positive regulation of gene expression, negative regulation of apoptotic process and so on ( As shown in Fig. 6a), and then top 20 important GO enrichment analysis items were selected (As shown in Fig. 6b, Table 4). As for KEGG enrichment analysis, the top 20 key pathways were identified (As shown in Fig. 7, Table 5), and the main pathways included PI3K–Akt, TNF and HIF-1 signaling pathway, the detail targets of regulation roles of these pathways are shown in Fig. 8a–f. The maps of KEGG pathway showed that the related targets of regulation roles were AKT, TNF, IL6, P53, VEGF, IL1B and so on.

Fig. 6
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a Results of biological process (top 10), cellular components (top 10), molecular function (top 10). b Top 20 items of GO enrichment analysis

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Table 4 Results of KEGG enrichment analysis (top 20)
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Fig. 7
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Top 20 items of KEGG enrichment analysis

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Table 5 The binding energies of top 3 main active compounds with top 7 key targets
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Fig. 8
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a KEGG pathway annotations of PI3K-Akt signaling pathway of Ermiaosan in the regulation of ulcerative colitis. Red rectangles represent the targets of regulation roles. b KEGG pathway annotations of PI3K-Akt signaling pathway of Ermiaosan in the regulation of ulcerative colitis. Green rectangles represent the targets of potential roles. c KEGG pathway annotations of TNF signaling pathway of Ermiaosan in the regulation of ulcerative colitis. Red rectangles represent the targets of regulation roles. d KEGG pathway annotations of TNF signaling pathway of Ermiaosan in the regulation of ulcerative colitis. Green rectangles represent the targets of potential roles. e KEGG pathway annotations of HIF-1 signaling pathway of Ermiaosan in the regulation of ulcerative colitis.Red rectangles represent the targets of regulation roles. f KEGG pathway annotations of HIF-1 signaling pathway of Ermiaosan in the regulation of ulcerative colitis.Green rectangles represent the targets of potential roles.

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3.4 The results of molecular docking verification

The top three main active compounds dihydroniloticin, quercetin, and beta-sitosterol 3-O-glucoside_qt had a tight linkage with ulcerative colitis verified through molecular docking, Among all docking of protein–ligands, the results showed that these 3 compounds had a strong affinity with the selected top 7 key targets, except for CTNNB1(PDB ID:6o9c), the binding energy with quercetin and beta-sitosterol 3-O-glucoside_qt were -4.29 kcal/mol and -4.89 kcal/mol, the rest target proteins are all less than -5 kcal/mol, all the detail information of binding energy with these 3 compounds of top 7 key targets are shown in Table 4, and the docking conformations of these targets of regulation roles AKT1, TNF, IL6,TP53, VEGFA, IL1B and CTNNB1 are shown in Fig. 9a–u.

Fig. 9
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a Dihydroniloticin with AKT1. b Dihydroniloticin with TNF. c Dihydroniloticin with IL6. d Dihydroniloticin with TP53. e Dihydroniloticin with VEGFA. f. Dihydroniloticin with IL1B. g Dihydroniloticin with CTNNB1. h Quercetin with AKT1. i Quercetin with TNF. j Quercetin with IL6. k Quercetin with TP53. l Quercetin with VEGFA. m Quercetin with IL1B. n Quercetin with CTNNB1. o Beta-sitosterol 3-O-glucoside_qt with AKT1. p Beta-sitosterol 3-O-glucoside_qt with TNF. q Beta-sitosterol 3-O-glucoside_qt with IL6. r Beta-sitosterol 3-O-glucoside_qt with TP53. s Beta-sitosterol 3-O-glucoside_qt with VEGFA. t Beta-sitosterol 3-O-glucoside_qt with IL1B. u Beta-sitosterol 3-O-glucoside_qt with CTNNB1

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4 Discussion

The incidence of UC is increasing year by year around the world, and it is listed as one of the most challenge and refractory diseases by World Health Organization [45, 46]. Pharmacotherapy is still the main measure in the treatment of UC, and the therapeutic goal is to control intestinal inflammation and improve immune disorders [47].

The combination of dampness and heat is the basic pathological factor of UC based on the theory of TCM, on the one hand, the main pathogenesis of recurrent bloody purulent stool is that the blood stasis caused by dampness-heat, and then blood stasis-heat impairs collaterals [48], thus the symptom of abdominal pain due to the blockage of blood vesselson. On the other hand, while intestinal mucosa steeped by dampness-heat, then the colon mucosa appears hyperemia and edema, and subsequently, after a long period of time, the rottenness of blood and muscle could result in ulcer or erosion on the colon mucosa [49].

Another physician who was also listed as one of the "Four Great Masters of ** and Yuan Dynasties" named Li Dongyuan, he used Ermiaosan as the main prescription to treat diarrhea caused by dampness-heat, the good curative effect provides a reference for the treatment of diarrhea in later generations [50]. The flexible application of traditional Chinese medicine in the dialectic-al treatment of UC has gained well clinical effects [51].

In the prescription of Ermiaosan, Cang Zhu could invigorate Spleen and eliminate dampness, then the dampness can't be generated without source(in TCM, the dampness comes from the dysfunction of spleen in transportation), and the heat can not be attached as the dampness is removed. As for Huang Bo, with its cold and bitter nature, it can restrain the warm and dry nature of Cang Zhu. When these two medicines are used together, one is warm and the other is cold, the combination use of them can clear away dampness, remove heat and thus dispel all symptoms [52].

Recent studies have found out that while Cang Zhu or Huang Bo used alone, there is no strong efficacy, but only when they are used together can the maximum pharmacodynamics be achieved, some components of the two medicinal materials interact with each other to make the effect more predominant [53].

Network pharmacology and molecular docking methods were useful tools that used to explore the possible pharmacological mechanisms of Ermiaosan against UC in our study, which showed that 46 compounds and 408 target genes were related to UC. The results of GO and KEGG pathway enrichment analyses indicates that the effects of Ermiaosan against UC may be due to the active compounds of Ermiaosan, especially for dihydroniloticin, quercetin and beta-sitosterol 3-O-glucoside_qt which could influence the regulation of the PI3K–Akt, TNF and HIF-1 signaling pathway. They may also be related to protein phosphorylation, positive regulation of cell proliferation, positive regulation of angiogenesis, inflammatory response, vascular endothelial growth factor receptor signaling pathway, positive regulation of gene expression, negative regulation of apoptotic process and so on. According to the results of PPI analysis and Cytoscape Hub, AKT1, TNF, IL6, TP53, VEGFA, IL1B and CTNNB1 were selected as key targets, and they reflect a strong affinity with dihydroniloticin, quercetin and beta-sitosterol 3-O-glucoside_qt as the results of the molecular docking method.

The previous study shows IL-1β,VEGF, tumor necrosis factor-αand IL-6 are expressed at higher levels in the patients with UC [54, 55]. Modern medical research verified that Ermiaosan can inhibit the expression of inflammatory factors and regulate immunity [56], And has an impact on the gastrointestinal tract [57]. And currently, animal experiment study indicates that quercetinin could play a prophylactic effect in terms of disease activity and bowel length in UC model of mice [58]. Scholars in recent years had proved that Ermiaosan can inhibit IL-1β, IL6, IL8, TNF- α, VEGF and other inflammatory factors, thus it can reduce the occurrence and development of inflammation, and promote neovascularization [59,60,61,62,63].

When ulcerative colitis occurs, more inflammatory mediators are involved in the lesion, and during the active phase of the inflammatory lesion, the expression of active inflammatory factors is more pronounced. The increased expression of VEGF in lesions can directly stimulate the division and proliferation of vascular endothelial cells, increase the gap between endothelial cells, increase vascular permeability, and exude fibrinogen, which can provide support for vascular structures and promote angiogenesis [64],

There are literature studies reporting that angiogenesis plays an important role in its pathological mechanism and mucosal repair. VEGF is currently considered the strongest and most specific proangiogenic factor, which can promote tissue repair and induce capillary regeneration [65]. And the viewpoint of preventing blood from overflowing out of the veins and alleviating intestinal bleeding is coincidental with TCM.

PPI network analysis shows that AKT1, TNF, IL6, TP53, VEGFA, IL1B and CTNNB1 may be important targets of Ermiaosan in the treatment of ulcerative colitis, and combined with the results of GO enrichment analysis, these targets involve in protein phosphorylation, positive regulation of cell proliferation, positive regulation of angiogenesis, inflammatory response, vascular endothelial growth factor receptor signaling pathway, positive regulation of gene expression, negative regulation of apoptotic process.

It explains that the blood entering components of Ermiaosan can alleviate the progression of UC by regulating AKT1, TNF, IL6, TP53, VEGFA, IL1B, CTNNB1 and other target proteins mainly related to positive regulation of cell proliferation, positive regulation of angiogenesis, inflammatory response, vascular endothelial growth factor receptor signaling pathway, positive regulation of gene expression to reduce inflammation, regulate immunity, promote cell regeneration and angiogenesis and other processes. And this process coincides with the view of traditional Chinese medicine to eliminate dampness-heat, then fundamentally prevent it from hurting collaterals, and promote muscle production to stop bleeding, promote the dissipation of pathological products, and prevent blood from overflowing the collaterals, thus accelerating intestinal healing.

KEGG pathway analysis shows that Ermiaosan plays therapeutic role in treating UC may be related to the regulation on PI3K–Akt, TNF and HIF-1 signaling pathways. It has been reported that PI3K/AKT/mTOR signaling pathway plays a significant role in the regulation of cell activation and inflammatory response [66], and some scientific tests estabblished that the expression of IL-1β, IL-6 and TNF-α can be down-regulated by inhibiting PI3K–Akt signal pathway, thus, which can play a protective, anti-inflammatory and anti-apoptotic role in intestinal mucosa of UC rats [67]. And it can inhibit the secretion of the inflammatory factor TNF-α and IL-6 by regulating HIF-1related signal pathway, then to ameliorate the inflammatory reaction of UC [68]. Further more, in our previous research, we found out that in the pathogenesis of UC, the immune response mediated by TNF signal pathway is closely related to it, while inhibiting the expression of this pathway can effectively reduce the content of IL-1, IL-6 and so on [69].

The above results indicate that Ermiaosan may regulate PI3K–Akt, TNF and HIF-1 signaling pathways by acting on key targets such as AKT1, TNF, IL6, TP53, VEGFA, IL1B and CTNNB1 can inhibit inflammation, regulate immunity, positive regulation of cell proliferation, positive regulation of angiogenesis improve mucosal barrier and etc., so as to exert therapeutic effect in UC with dampness-heat syndrome based on active compounds of dihydroniloticin, quercetin and beta-sitosterol 3-O-glucoside_qt, and they reflect a strong affinity with each other.

5 Conclusions

In conclusion, the results of our study show that Ermiaosan may play therapeutic role in treating UC with dampness-heat syndrome based on active compounds of dihydroniloticin, quercetin and beta-sitosterol 3-O-glucoside_qt, and they mainly acting on seven targets AKT1, TNF, IL6, TP53, VEGFA, IL1B and CTNNB1 may be related to the regulation on PI3K–Akt, TNF and HIF-1 signaling pathways.