Introduction
Xia Sang Ju (XSJ) granule is a traditional Chinese drug as well as a kind of Chinese herbal tea which is made up of Prunellae spica (Xia Ku Cao), Mori folium (Sang Ye), and Flos Chrysanthemi Indici (Ye Ju Hua). It originates from the classic prescription called Sang Ju Yin that was recorded in the Treatise on Differentiation and Treatment of Epidemic Febrile Diseases (Wen Bing Tiao Bian) by Wu Jutong in the Qing Dynasty. Though XSJ is well-known for treating fever, headache, and sore throat, hypertension is also one of the main functions of XSJ.1 However, how XSJ plays a part in anti-hypertensive activity remains unclear, due to the complexity of Traditional Chinese medicine (TCM).
Hypertension is characterized by elevated blood pressure in arteries, and is the most common of the chronic diseases and one of the most important risk factors for cerebrovascular diseases; causing an estimated 7.5 million deaths, it accounts for 12.8% of the total deaths.2 So far, commonly-used anti-hypertensive drugs include diuretics, beta-blockers, angiotensin converting enzyme inhibitors, calcium channel blockers, angiotensin receptor blockers, etc.3 Unfortunately, no specific medicine can yet cure high blood pressure.
TCMs are extensively used in eastern countries, as treatments for such chronic diseases as hypertension, diabetes and stroke, and their advantages have been gradually recognized through the increasing number of people who seek natural herbal remedies in western countries.4 Most existing research is limited to a certain gene target while interpreting the mechanism of a drug, an approach which may ignore the multi-component, multi-target, multi-pathway characteristics of Chinese herbal formulae.4 Network pharmacology, based on an integrated multidisciplinary concept, is a powerful tool that analyzes the multi-level network of molecular-target-pathway-disease through the interaction between TCM and disease from a holistic perspective.5–9
In this study, firstly the active compounds of XSJ were screened computationally, according to oral bioavailability (OB) and drug likeness (DL)10 and then the potential compound targets and hypertension-related targets were predicted. Finally the XSJ-compound-hypertension networks were constructed, so as to deeply understand the potential underlying mechanism of the anti-hypertensive effect of XSJ.
Materials and methods
Compounds of XSJ
The Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (commonly known as TCMSP; http://www.tcmspw.com/tcmsp.php , version 2.3)11 was used to collect the compound information of XSJ. A total of 60 compounds in Prunellae spica, 269 compounds in Mori folium, and 30 compounds in Flos Chrysanthemi Indici were found. To select the potential active compounds, OB and DL,10 the most important criteria for drug screening, was set to be ≥30% and ≥0.18, respectively.12
Compound targets
To predict the most relevant targets of compounds, the simplified molecular-input line-entry system (referred to as SMILES) format of each compound was input into the SwissTargetPrediction website (http://www.swisstargetprediction.ch/ ) with the organism limited to Home sapiens.13,14
Hypertension targets
Genes associated with hypertension were searched from the Online Mendelian Inheritance in Man (commonly known as OMIM) database (http://www.omim.org/ )15,16 and GeneCards database (https://www.genecards.org/ )17 using the keywords “hypertension” or “high blood pressure”.
Protein-protein interaction
The STRING database (https://string-db.org/ , version 10.5) was used to analysis the protein-protein interaction.18 Protein names were input and organism was limited to Homo sapiens. Data of protein-protein interactions were obtained and saved as TSV files.
GeneMANIA analysis
A weighted composite functional interaction network for hypertension-related genes were constructed by GeneMANIA (https://genemania.org/ ).19 Genes of interest were input and organism was limited to Homo sapiens.
Gene ontology enrichment analysis
Gene ontology enrichment analysis for biological processes and Kyoto Encyclopedia of Genes and Genomes (commonly known as KEGG) pathways were performed by Database for Annotation, Visualization and Integrated Discovery, commonly known as DAVID, 6.8 server (https://david.ncifcrf.gov/ ).21,22
Results
Screen of active compounds
In total, 359 compounds in XSJ were obtained from the TCMSP database. After filtering by OB and drug likeness parameters, 11 compounds from Prunellae spica, 29 compounds from Mori folium, and 12 compounds from Flos Chrysanthemi Indici with favorable pharmacokinetic profiles were included for further investigation (Table 1). Specifically, beta-sitosterol and quercetin were found in all three of the herbs, and kaempferol as well as stigmasterol were originated from both Prunellae spica and Mori folium, while luteolin was found in Prunellae spica and Flos Chrysanthemi Indici.
Table 1Active compounds in the herbs and their properties
Mol ID | Compound | OB, % | DL | Herbs |
---|
MOL000358 | Beta-sitosterol | 36.91 | 0.75 | Prunellae spica, Mori folium, Flos Chrysanthemi Indici |
MOL000422 | Kaempferol | 41.88 | 0.24 | Prunellae spica, Mori folium |
MOL004355 | Spinasterol | 42.98 | 0.76 | Prunellae spica |
MOL000449 | Stigmasterol | 43.83 | 0.76 | Prunellae spica, Mori folium |
MOL004798 | Delphinidin | 40.63 | 0.28 | Prunellae spica |
MOL000006 | Luteolin | 36.16 | 0.25 | Prunellae spica, Flos Chrysanthemi Indici |
MOL006767 | Vulgaxanthin-I | 56.14 | 0.26 | Prunellae spica |
MOL006772 | Poriferasterol monoglucoside_qt | 43.83 | 0.76 | Prunellae spica |
MOL006774 | Stigmast-7-enol | 37.42 | 0.75 | Prunellae spica |
MOL000737 | Morin | 46.23 | 0.27 | Prunellae spica |
MOL000098 | Quercetin | 46.43 | 0.28 | Prunellae spica, Mori folium, Flos Chrysanthemi Indici |
MOL001771 | Poriferast-5-en-3beta-ol | 36.91 | 0.75 | Mori folium |
MOL002218 | Scopolin | 56.45 | 0.39 | Mori folium |
MOL002773 | Beta-carotene | 37.18 | 0.58 | Mori folium |
MOL003842 | Albanol | 83.16 | 0.24 | Mori folium |
MOL003847 | Inophyllum E | 38.81 | 0.85 | Mori folium |
MOL003850 | 26-Hydroxy-dammara-20,24-dien-3-one | 44.41 | 0.79 | Mori folium |
MOL003851 | Isoramanone | 39.97 | 0.51 | Mori folium |
MOL003856 | Moracin B | 55.85 | 0.23 | Mori folium |
MOL003857 | Moracin C | 82.13 | 0.29 | Mori folium |
MOL003858 | Moracin D | 60.93 | 0.38 | Mori folium |
MOL003859 | Moracin E | 56.08 | 0.38 | Mori folium |
MOL003860 | Moracin F | 53.81 | 0.23 | Mori folium |
MOL003861 | Moracin G | 75.78 | 0.42 | Mori folium |
MOL003862 | Moracin H | 74.35 | 0.51 | Mori folium |
MOL003879 | 4-Prenylresveratrol | 40.54 | 0.21 | Mori folium |
MOL000433 | | 68.96 | 0.71 | Mori folium |
MOL000729 | Oxysanguinarine | 46.97 | 0.87 | Mori folium |
MOL001439 | Arachidonic acid | 45.57 | 0.2 | Mori folium |
MOL001506 | Supraene | 33.55 | 0.42 | Mori folium |
MOL003759 | Iristectorigenin A | 63.36 | 0.34 | Mori folium |
MOL003975 | Icosa-11,14,17-trienoic acid methyl ester | 44.81 | 0.23 | Mori folium |
MOL006630 | Norartocarpetin | 54.93 | 0.24 | Mori folium |
MOL007179 | Linolenic acid ethyl ester | 46.1 | 0.2 | Mori folium |
MOL007879 | Tetramethoxyluteolin | 43.68 | 0.37 | Mori folium |
MOL013083 | Skimmin (8CI) | 38.35 | 0.32 | Mori folium |
MOL001689 | Acacetin | 34.97 | 0.24 | Flos Chrysanthemi Indici |
MOL001790 | Linarin | 39.84 | 0.71 | Flos Chrysanthemi Indici |
MOL000359 | Sitosterol | 36.91 | 0.75 | Flos Chrysanthemi Indici |
MOL008173 | Daucosterol_qt | 36.91 | 0.75 | Flos Chrysanthemi Indici |
MOL008915 | Acacetin-7-O-β-D-galactopyranoside | 50.19 | 0.77 | Flos Chrysanthemi Indici |
MOL008918 | Arteglasin A | 52.45 | 0.33 | Flos Chrysanthemi Indici |
MOL008919 | (2S,6S,7aR)-2-[(1E,3E,5E,7E,9E,11E,13E,15E)-16-[(4S)-4-Hydroxy-2,6,6-trimethyl-1-cyclohexenyl]-1,5,10,14-tetramethylhexadeca-1,3,5,7,9,11,13,15-octaenyl]-4,4,7a-trimethyl-2,5,6,7-tetrahydrobenzofuran-6-ol | 59.52 | 0.55 | Flos Chrysanthemi Indici |
MOL008924 | Azuleno(4,5-b)furan-2(3H)-one, 4-(acetyloxy)-3a,4,5,6,6a,7,9a,9b-octahydro-6-hydroxy-6,9-dimethyl-3-methylene-, (3aR-(3aalpha,4alpha,6alpha,6aalpha,9aalpha,9bbeta))- | 68.44 | 0.27 | Flos Chrysanthemi Indici |
MOL008925 | (3aR,4S,6R,6aR,9aR,9bR)-4,6-Dihydroxy-6,9-dimethyl-3-methylene-4,5,6a,7,9a,9b-hexahydro-3aH-azuleno[5,4-d]furan-2-one | 40.08 | 0.19 | Flos Chrysanthemi Indici |
Hypertension network analysis
In total, 189 genes associated with hypertension were obtained from the OMIM and GeneCards databases after elimination of false positives and repetitive genes (Table s1). The interaction of hypertension target genes was analyzed by GeneMANIA (Fig. 1, Table s2) and a network containing 274 nodes and 10,742 edges was constructed. This result showed that 55.08% of genes were co-expressed, and 20.87% were expressed in the same tissue or their products in the same cellular location. Among the genes, 11.02% were found to be involved in physical interaction, while 4.86% were engaged in predicted functional relationships. Up to 3.61% were identified as possibly participating in the same pathway, 3.01% had shared protein domains, and 1.55% had genetic interactions that were functionally associated.
Analysis of compound-compound target network
The SMILES format of each compound was input into SwissTargetPrediction, and predicted compound targets were obtained (Table s3). A compound-compound target network was constructed, consisting of 282 nodes and 703 edges (Fig. 2). These results showed that some target genes may be modulated by many compounds, such as the ESR1, AR, MAPT, CYP19A1, and HMGCR genes. While the AOX1, CTSK, OCD1, SRC, RARA, NOX4, and CDC25B genes are hit by only one compound. Interestingly, both SLC6A4 and P05093 can be regulated by poriferast-5-en-3beta-ol, beta-sitosterol, poriferasterol mo noglucoside_qt, stigmast-7-enol, spinasterol, daucosterol_qt, and sitosterol. Both the NR1H2 and NR1H3 genes can be modulated by 26-hydroxy-dammara-20,24-dien-3, poriferast-5-en-3beta-ol, beta-sitosterol, poriferasterol monoglucoside_qt, stigmast-7-enol, spinasterol, stigmasterol, daucosterol_qt, and sitosterol. This predicted compound-compound target network strengthens the concepts of multi-compound-multi-target of TCM, in which different active components in XSJ may regulate the same targets and one active ingredient may also modulate various targets.
Hypertension-related compound target network analysis
Eleven genes with commonalities between hypertension genes and compound targets were found and a hypertension-related compound target network was constructed (Fig. 3, Table 2), which contained 39 nodes and 39 edges. Among the 28 compounds directly interacting with these genes, 8 of them came from Prunellae spica, 18 were from Mori folium, and 5 were from Flos Chrysanthemi Indici. The protein classes for the 11 common genes were obtained from the DisGeNET database. The XSJ and hypertension-related targets’ protein-protein interaction network is shown in Figure 4. ESR2 and SLC6A2, both of which play a role in nucleic acid binding, as receptor and transcription factor, or transporter, were the most frequent genes targeted by the compounds. ESR2 and SLC6A2 are known to be important to cardiovascular physiology and blood pressure regulation.23–27 These results suggested that the anti-hypertension effect of XSJ may be regulated mainly by ESR2 and SLC6A2 (Table 3).
Table 2Candidate compounds from Xia Sang Ju and their potential targets associated with hypertension
No. | Compound | Target gene code | Herbs |
---|
1 | Stigmast-7-enol | SLC6A2 | Prunellae spica |
2 | Spinasterol | SLC6A2, ESR2 | Prunellae spica |
3 | Poriferasterol monoglucoside_qt | SLC6A2 | Prunellae spica |
4 | Delphinidin | ADORA2A | Prunellae spica |
5 | Morin | ESR2 | Prunellae spica |
6 | Stigmasterol | ESR2 | Prunellae spica, Mori folium |
7 | Vulgaxanthin-I | MGAM | Prunellae spica |
8 | Beta-sitosterol | SLC6A2 | Prunellae spica, Mori folium, Flos Chrysanthemi Indici |
9 | Poriferast-5-en-3beta-ol | SLC6A2, ESR2 | Mori folium |
10 | Isoramanone | ESR2, NR3C2, NR3C1 | Mori folium |
11 | Beta-carotene | ADRA2B, ESR2 | Mori folium |
12 | Moracin F | ESR2 | Mori folium |
13 | Moracin G | ESR2 | Mori folium |
14 | Moracin H | ESR2 | Mori folium |
15 | Moracin E | ESR2 | Mori folium |
16 | Moracin D | ESR2 | Mori folium |
17 | Moracin B | ESR2 | Mori folium |
18 | Iristectorigenin A | ESR2, HSD11B2 | Mori folium |
19 | Albanol | HIF1A, ESR2 | Mori folium |
20 | 26-Hydroxy-dammara-20,24-dien-3 | HSD11B1 | Mori folium |
21 | Icosa-11,14,17-trienoic acid methyl ester | HSD11B1, PPARG | Mori folium |
22 | 4-Prenylresveratrol | PPARG | Mori folium |
23 | Arachidonic acid | PPARG | Mori folium |
24 | Tetramethoxyluteolin | ADORA2A | Mori folium |
25 | Arteglasin A | SLC6A2, ESR2 | Flos Chrysanthemi Indici |
26 | Daucosterol_qt | SLC6A2, ESR2 | Flos Chrysanthemi Indici |
27 | Sitosterol | SLC6A2, ESR2 | Flos Chrysanthemi Indici |
28 | Acacetin-7-O-β-D-galactopyranos | ADORA2A | Flos Chrysanthemi Indici |
Table 3Hypertension-related targets of Xia Sang Ju
No. | Target | Uniprot ID | Gene code | Protein class | Frequency |
---|
1 | Estrogen receptor-beta | Q92731 | ESR2 | Nucleic acid binding; receptor; transcription factor | 17 |
2 | Solute carrier family 6 member 2 | P23975 | SLC6A2 | Transporter | 8 |
3 | Nuclear receptor subfamily 3, group C, member 1 | P04150 | NR3C1 | Nucleic acid binding; receptor; transcription factor | 1 |
4 | Nuclear receptor subfamily 3, group C, member 2 | P08235 | NR3C2 | Nucleic acid binding; receptor; transcription factor | 1 |
5 | Adenosine receptor A2a | P29274 | ADORA2A | Receptor | 3 |
6 | Adrenoceptor alpha 2B | P18089 | ADRA2B | Receptor | 1 |
7 | Maltase-glucoamylase | O43451 | MGAM | Hydrolase | 1 |
8 | Hypoxia-inducible factor 1, alpha subunit | Q16665 | HIF1A | Nucleic acid binding; transcription factor | 1 |
9 | 11-Beta-hydroxysteroid dehydrogenase, type I | P28845 | HSD11B1 | None | 1 |
10 | Peroxisome proliferator-activated receptor-gamma | P37231 | PPARG | Nucleic acid binding; receptor; transcription factor | 3 |
11 | Corticosteroid 11-beta-dehydrogenase isozyme 2 | P80365 | HSD11B2 | Oxidoreductase | 1 |
Biological functional analysis
Biological functions of the hypertension-related compound targets were annotated to explain the possible mode of action of XSJ in hypertension. Gene ontology enrichment analysis was performed on the 11targets by DAVID. The top five biological processes were cellular nitrogen compound biosynthetic process, organic cyclic compound biosynthetic process, aromatic compound biosynthetic process, heterocycle biosynthetic process, and nucleobase-containing compound biosynthetic process (Fig. 5a). The significant KEGG pathways included neuroactive ligand-receptor interaction, steroid hormone biosynthesis, aldosterone-regulated sodium reabsorption, PPAR signaling pathway, and thyroid cancer (Fig. 5b). These results elucidated that XSJ may exert anti-hypertension activity through multi-biological processes as well as multi-pathways.
Discussion
The escalation of hypertension cases global effects. Coupled with lack of any promising hypotensor, this then requires multiple approaches for treatment, including lifestyle modifications and new drugs. Though XSJ is generally used for treatment of fever, headache, sore throat, and as a beverage for clearing heat, hypertension is also one of the major functions.1 Nevertheless, the mechanism of action for XSJ working on hypertension remains to be fully understood.
During the development of hypertension, endothelin, nitric oxide, and angiotensin II are key factors. Vascular endothelial cells can produce both systolic and vasoactive substances for maintaining vasomotor balance and normal tension. Endothelin is the strongest vasoconstrictor and promotes smooth muscle proliferation,28 while nitric oxide is the main vasodilator substance released by vascular endothelial cells. Endothelin harbors angiotensin-converting enzyme activity that catalyzes the synthesis of angiotensin II; however, angiotensin II can induce expression of the endothelin gene in endothelial cells. Nitric oxide inhibits the production and release of endothelin, and also inhibits the release of renin, which in turn inhibits the production of angiotensin II.29–31
Despite few publications in the publicly available literature describing the anti-hypertension activity of XSJ so far, recent studies have proven that the extracts and some compounds of all three herbs in XSJ have direct or indirect anti-hypertensive effect, consistent with some of the biological processes found in our study. Ethanol extract of Prunella vulgaris L has been shown to increase the content of nitric oxide, to decrease the content of endothelin and angiotensin II, and finally to reduce blood pressure significantly in a spontaneously hypertensive rat model (e.g., positive regulation of the nitric oxide biosynthetic process, regulation of the systemic arterial blood pressure by endothelin).32 Flavonoid compounds in Mori folium have also been found to expand the coronary vessels, improve myocardial circulation, and reduce blood pressure (e.g., regulation of blood pressure).33 Ethanol extract of Flos Chrysanthemi Indici has shown hypotensive effect in clinical studies.34 Intriguingly, luteolin from Prunella vulgaris L and Flos Chrysanthemi Indici might inhibit vascular smooth muscle cell proliferation and migration, which is pivotal in the development of arterial remodeling during hypertension (e.g., blood vessel remodeling), by suppressing transforming growth factor-β receptor 1 signaling.35
Luteolin can ameliorate hypertensive vascular remodeling through inhibition of proliferation and migration of angiotensin II-induced vascular smooth muscle cells, a process that is mediated by the regulation of MAPK signaling pathway and the production of reactive oxygen species (e.g., blood vessel remodeling, positive regulation of the reactive oxygen species metabolic process).36 Quercetin from Prunella vulgaris L and Flos Chrysanthemi Indici can attenuate hypertension via reduction in oxidative stress and improving endothelial function, as shown in an acute fluoride-induced hypertension and cardiovascular complications model.37 Furthermore, quercetin was shown to reduce hypertension-induced vascular remodeling, oxidative stress and MMP-2 activity in aortas in the two-kidney one-clip hypertensive Wistar rat model (e.g., blood vessel remodeling).38 Quercetin can also attenuate vascular contraction through the LKB1-AMPK signaling pathway (e.g., regulation of vasoconstriction).39 Delphinidin and quercetin were shown to block the renin-angiotensin system signaling pathway through inhibition of angiotensin-converting enzyme activity and decreasing the production of its mRNA.40 Finally, linarin from Flos Chrysanthemi Indici was shown to directly or indirectly activate macrophages and affect the inhibition of nitric oxide that is responsible for vasodilation and hypotension (e.g., vasodilation).41
The current study provided a prediction of the potential mechanism of XSJ as treatment of hypertension, based on a computational approach. There are some limitations of this work. First, the components in TCM herbs have not yet been completely identified; thus, the databases of compounds are not complete, precluding their ability to represent the integral spectrum of compounds responsible for the anti-hypertension effect. Second, all of the data were based on silico analysis, and as such there may be many false positive and false negative interactions between the found compound-protein and protein-protein interactions. What’s more, the relationship between XSJ and anti-hypertension activity was identified by enrichment analysis. Therefore, the associations presented herein should be further investigated for experimental verification to achieve more accurate and reliable inferences in the future.
Future directions
The associated biological processes and pathways need further investigation for confirmation of the exact mechanism of XSJ in hypertension treatment.
Conclusions
Collectively, the findings presented herein suggest that the compounds in XSJ exert their anti-hypertensive effect via multiple biological processes, such as regulation of blood pressure, blood vessel remodeling, regulation of the nitric oxide biosynthetic process and so on, which is in accord with the TCM therapy concept of “multiple compounds-multiple targets-multiple effects”. Though further experiments are needed to verify this finding, this study revealed the potential anti-hypertensive mechanism of XSJ from holistic and systematic perspectives by using network pharmacology.
Supporting information
Supplementary material for this article is available at https://doi.org/10.14218/JERP.2020.00008 .
Table s1
Hypertension targets.
(XLS)
Table s2
Interaction of genes related to hypertension.
(XLSX)
Table s3
Relationships between compounds and targets.
(XLSX)
Abbreviations
- DAVID:
Database for Annotation, Visualization and Integrated Discovery
- KEGG:
Kyoto Encyclopedia of Genes and Genomes
- OB:
oral bioavailability
- DL:
drug likeness
- OMIM:
Online Mendelian Inheritance in Man
- SMILES:
simplified molecular-input line-entry system
- TCMSP:
Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform
- TCM:
traditional Chinese medicine
- XSJ:
Xia Sang Ju
Declarations
Acknowledgement
The author wishes to thank Zhong Xiaotian and Gao Jiansheng for valuable comments.
Funding
This study was supported by Grants from Shenzhen Overseas High-Caliber Peacock Foundation (KQTD2015071414385495).
Conflict of interest
None.