To Explore the Potential Mechanism of Yiqing Capsule in the Treatment of COVID-19 Based on Network Pharmacology

Objective: To select the ingredients and targets of Yiqing capsule in treating COVID-19 based on network pharmacology, then to explore the potential mechanism of Yiqing capsule in treating COVID-19. Methods: We screened the ingredients and targets of Yiqing capsule on Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), and target genes for COVID-19 in GeneCards database, constructed drug-ingredient-target network through software Cytoscape 3.7.2, and constructed protein protein interaction network (PPI) network through STRING database. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of key gene targets of Yiqing capsule are used to treat COVID-19 through software R5.3.2. Results: We got 42 ingredients, 42 potential therapeutic targets, 1643 GO items and 970 pathways in our study. The main pathway including IL-17 signaling pathway, Chagas disease (American trypanosomiasis), Influenza A, and TNF signaling pathway. Conclusion: Yiqing capsule plays a role in treating COVID-19 through multiple ingredients, multiple targets and multiple pathways.


Introduction
Coronavirus disease 2019 (COVID-19) was named by the WHO on January 12, 2020, and the pathogen was named SARS-CoV-2 [1]. COVID-19 is caused by a novel, highly infectious coronavirus resulting in a pandemic. The main clinical symptoms are fever and dry cough. A few are presented with gastrointestinal symptoms, severe respiratory failure [2]. COVID-19 is considered to be a blight in traditional Chinese medicine (TCM) [3]. The third edition of "diagnosis and treatment scheme of COVID-19" published by the government of China (GOC) recommended Chinese medicine therapy in the treatment in COVID-19, achieving good results in prophylaxis and treatment. Research on mining the regularity of Chinese medicine prescription in treating COVID-19 had also been shown that antipyretic and cathartic (qing re xie xia) drugs are used throughout all the stages of anti-COVID-19 [4].
The formula of Yiqing capsule is the representative prescription of fire cathartic. It was derived from the "Xie Xin Tang [7]. Therefore, our study analyzed the ingredients, targets and pathway of Yiqing capsule, to explore the possible effect and potential mechanism of Yiqing capsule in the treatment of COVID-19, and further verify the importance of fire relieving prescription in the treatment of COVID-19, in order to provide basis for further basic research and clinical application.

Constructed Drug-Ingredient-Target Network
Target genes for COVID-19 were searched for in the GeneCards database

Constructed PPI Network
The potential therapeutic targets of Yiqing capsule in treatment of COVID-19 were imported into the STRING database (https://string-db.org/). The organism selected was "Homo sapiens". The minimum required interaction score was set to 0.4. Then the key targets were screened through software R5.3.2.
Y. Wang et al.

Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) Enrichment Analysis
The GO enrichment analysis and KEGG pathway analysis of key gene targets of Yiqing capsule in treating COVID-19 were analyzed by software R5.3.2, with P ≤ 0.05 as screening conditions. Every item was sorted according to the number of targets involved in each item and the lgP value.

Screened the Ingredients and Targets of Yiqing Capsule
We selected 259 targets from the GeneCards database with the key words "Novel Coronavirus Pneumonia". Furthermore, we mapped a total of 42 potential therapeutic targets in Yiqing capsule. We also screened 42 ingredients in this study.
The results are shown in Table 1 and Figure 1.

Constructed Drug-Ingredient-Target Network
We constructed a drug-ingredient-target network of 42 selected targets of Yiqing capsule in treating COVID-19 through software Cytoscape (shown in Figure 2). We got 86 nodes and 263 edges. When sorted by degree, the median ingredient number was 4, the top 6 ingredients potentially interacting with the targets were coptisine, naloe-emodin, baicalein, beta-sitosterol, wogonin, Eriodyctiol (flavanone), and oroxylin a.

Constructed PPI Network
The 42 potential targets of Yiqing capsule in the treatment of COVID-19 were constructed to a PPI network through STRING database (Shown in Figure 3).

GO Nrichment Analysis and KEGG Pathway Analysis
Forty-two potential targets were analyzed through software R, resulting in 1643 GO items (76 MF items, 15 CC items, and 1522 BP items), as shown in Figure 4. We got 970 pathways through KEGG pathway enrichment analysis (shown in Figure 5), such as AGE-RAGE signaling pathway in diabetic complications, IL-17 signaling pathway, Chagas disease (American trypanosomiasis), Influenza A, TNF signaling pathway, and Pertussis.

Discussion
COVID-19 is considered to be a blight in the seventh edition of "diagnosis and treatment scheme of COVID-19" published by National Health Commission of the People's Republic of China. COVID-19 is mainly caused by "Warm heat   [9]. A published study showed that "Qing xia" plays a key role in the diagnosis and treatment of epidemic diseases [10].  [11]. Baicalein has the same binding energy with the 2019-ncov 3CL hydrolase through molecular docking as does the antiviral drug Remdesivir [12]. Lin, et al. reported beta-sitostero showed an anti-coronavirus effect on blocking the cleavage process of 3CLpro of coronavirus [13]. The results of GO and KEGG analysis shown that the main pathway of Yiqing capsule in treating COVID-19 were GE-RAGE signaling pathway in diabetic complications, IL-17 signaling pathway, Chagas disease (American trypanosomiasis), Influenza A, TNF signaling pathway, and Pertussis. Pathways mainly involve virus infection, inflammation, apoptosis and immune regulation. It is suggested that Yiqing capsule may act on a variety of cytokines to fight inflammation and inhibit cytokine storms in the treatment of COVID-19 [14].

Conclusion
In summary, the network pharmacology method showed that Yiqing capsule can treat COVID-19 through multiple components, targets and pathways, but it also had some limitations. The tropism of Yiqing capsule is greatly bitter and cold, leading to damage the spleen and stomach injury when taken chronically. Therefore, doctors should limit use of Yiqing capsule to acute treatment. In addition, some of the results in our study still need to be verified by further laboratory tests and clinical studies.

Funding
This study was funded by the Study and Development Fund for Sciences and Technology in Chengde City (No. 201701A087).