Abstract
Objective
To explore the metabolic regulatory mechanisms of sodium houttuyfonate (SH), a herbal-originated anti-inflammatory drug that has been used clinically in China for many years, in preventing diseases.
Methods
Rats received SH intragastrically at 24 mg/kg body weight once a day for 4 consecutive weeks, based on the equivalent dose of SH in rat vs. human. The abdominal aorta blood of the rats was collected to separate serum for metabolomic analyses by ultraperformance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS).
Results
Compared to the blank control, SH treatment induced 337 differential metabolites (DMs) with a fold change (FC) ≥ 2.0 or ≤0.50. Among them, 191 DMs can be annotated in the Human Metabolome Database (HMDB), and 98 DMs can be enriched in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including 11 hormones and hormone-related compounds, 18 organic acids and their derivatives, 8 nucleotides and their metabolites, 6 amino acid-related metabolites, etc. These DMs were enriched in 143 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, with the tricarboxylic acid (TCA) cycle and steroid hormone biosynthesis significantly altered. Finally, progesterone (MW0062186) and monoacylglycerols (MEDL02326) were the top up-regulated (5.47E+2) and the most down-regulated (1.36E-3) metabolites in the annotated DMs, respectively.
Conclusion
Our findings suggest a metabolic reprogramming mechanism of SH in preventing diseases, and this mechanism may guide the possible use of SH in the future.
Keywords
Introduction
Houttuynia cordata Thunb. (HCT) is a traditional Chinese medicine (TCM) with the function of reducing fever and detoxifying. In Asia, especially in China, it has a long history of treating lung-related diseases, such as pneumonia, bronchitis, and lung abscesses. 1 As a perennial herb, HCT is not only a Chinese herbal medicine but also a food, known as Yu-Xing-Cao in Chinese. 2 During the outbreak of severe acute respiratory syndrome (SARS) in late 2002 to mid-2003, HCT was recommended to the public in China as a preventive ingredient and showed a significant anti-complementary activity. 3 Houttuynin (decanoyl acetaldehyde) is the main active compound in the volatile oil extracted from HCT, but it is difficult to directly convert into a clinical drug due to its instability and low solubility in water. 4 To overcome these defects, sodium houttuyfonate (SH, C12H23O5SNa), an addition compound of sodium bisulfite and houttuynin, was developed as an alternative drug that has been extensively applied in antimicrobial areas in China and proven to have the same pharmacological effects as houttuynin, which is more stable and soluble in water. 5 SH exhibits a variety of pharmacological effects, such as antibacterial, antiviral, anti-inflammatory, and injury -protective activities. 6 The underlying mechanisms include preserving the normal glutamatergic system, 7 regulating the TNF-α/JAK-STAT signaling pathway, 8 inhibiting the NLRP3/GSDMD pathway, 9 interfering with the Dectin-1/NF-κB/miR-32-5p/NFKBIZ axis, 10 suppressing the TLR4/NF-ĸB signaling pathway, 11 etc. We postulated that clarifying the metabolic regulatory mechanism of SH is crucial to expand its clinical applications. The aim of this study is to explore the metabolic regulatory mechanisms of SH in preventing diseases by rat serum metabolomic analyses. Our findings suggest a metabolic reprogramming mechanism of SH in preventing diseases, and this mechanism may guide the possible use of SH in the future.
Materials and Methods
Drugs and Chemical Reagents
Abbreviations
Instruments
-80°C freezer, 906-ULTS, Thermo Scientific (Waltham, MA, USA); mass spectrometer (MS), TripleTOF 6600+, SCIEX (Foster City, CA, USA); ultra performance liquid chromatography (UPLC), LC-30A, Shimadzu (Kyoto, Japan); centrifuge, 5424R, Eppendorf (Hamburg, Germany);one hundred thousandth electronic balance, MS105DΜ, Mettler Toledo Instrument Co., Ltd. (Zurich, Switzerland); centrifugal concentrator, CentriVap, LABCONCO (Kansas City, MO, USA); pipette, Research plus, Eppendorf (Hamburg, Germany);automation workstation, Biomek i5, Beckman Coulter (California, USA).
Rat Treatment With SH
Twelve ten-week-old Wistar female rats (body weight:110±10g) were obtained from Henan Provincial Medical Laboratory Animal Center (license number SCXK (YU) 2019–0002) and were randomly divided into two groups: normal group and SH group, with 6 rats in each group. Animal experiments were conducted at the Henan University Laboratory Animal Center, and the time duration was 5 weeks (including a one-week adaptation period). The rats were kept in an environment with a temperature of 22 ± 2 °C, a humidity of 50 ± 10%, and a light/dark cycle of 12 h. All animal procedures were authorized by the Medical Ethics Committee of Henan University (ethical batch number HUSAM 2024-168) and carried out according to the Guide for the Care and Use of Laboratory Animals. Rats in the SH group received SH at a dose of 24 mg/kg body weight (the tablet was triturated and suspended in 0.5% of the CMC-Na solution) via gavage once a day for 4 consecutive weeks based on the equivalent dose of rat vs. human, while rats in the normal group received intragastrically an equal volume of the CMC-Na solution. At the end of the treatment, the rats were fasted for 12 h but allowed free access to drinking water, and then the abdominal aorta blood was collected under anesthesia with pentobarbital sodium (60 mg/kg body weight) to separate serum for metabolomic analyses. 12 The reporting of this study conforms to ARRIVE 2.0 guidelines. 13 Non-targeted serum metabolomics was performed by ultraperformance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS) at Wuhan Metware Bio. Co., Ltd. (Wuhan, China) according to the standardized protocol, 14 and the time duration was 4 weeks.
Sample Preparation and Extraction
Liquid Samples Class I
The method was optimized based on a previous report. 15 Briefly, the serum samples stored in the -80 °C refrigerator were thawed on ice and vortexed for 10 s. Then, 50 μL of sample and 300 μL of extraction solution (ACN: Methanol = 1:4) containing internal standards were added into a 2 mL microcentrifuge tube. The sample was vortexed for 3 min and then centrifuged at 12,000 rpm at 4 °C for 10 min. Next, 200 μL of the supernatant was collected and cooled at -20 °C for 30 min and then centrifuged at 12,000 rpm at 4 °C for 3 min. Finally, a 180 μL aliquot of supernatant was transferred for UPLC-MS analysis.
U PLC Conditions
T3 column flow gradient
Solvent A: 0.1 % formic acid in water;
Solvent B: 0.1 % formic acid in acetonitrile.
MS Conditions (AB)
AB TripleTOF 6600 mass parameters
Mass error (ppm) =
Data Analyses
The software used in data analysis
The raw data were standardized by zero-centering and Z-score.
Zero-centering (x’) = x-µ; Z-score (x’) = (x-µ)/σ, x’ is the calibrated data, x is the raw data, µ is the mean and σ is the standard deviation.
The components with a score > 0.5 and coefficient of variation (CV) < 0.3 were integrated in the positive and negative ion modes.
Principal Component Analysis (PCA)
Unsupervised PCA was performed by statistics function prcomp in R (https://www.r-project.org). The data were unit variance scaled before unsupervised PCA. In order to find out the maximum differences between two groups, Partial Least Squares Discriminant Analysis (PLS-DA) was utilized. 20 Differential variables were chosen and validated using the false detection rate (FDR)-corrected Mann-Whitney U test. 21
Hierarchical Cluster Analysis (HCA) and Pearson Correlation Coefficients (PCC)
The HCA results of samples and metabolites were presented as heatmaps with dendrograms, while PCC between samples was calculated by the cor function in R and presented as heatmaps. Both HCA and PCC were carried out by the R package ComplexHeatmap. For HCA, normalized signal intensities of metabolites (unit variance scaling) were visualized as a color spectrum. 22
Enrichment for the metabolic pathways was recognized as significant when their p values were < 0.05 based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.
Differential Metabolites (DMs) Selected
Metabolite identification relied on mass error, PubChem, score, and level. For two-group analyses, DMs were determined by fold change (FC) ≥ 2 or ≤ 0.5. 23
KEGG Annotation and Enrichment Analyses
Identified metabolites were annotated using the KEGG Compound database (https://www.kegg.jp/kegg/compound/), and annotated metabolites were then mapped to the KEGG Pathway database (https://www.kegg.jp/kegg/pathway.html). Significantly enriched pathways were identified with a hypergeometric test’s p-value for a given list of metabolites. 24
Results
Metabolite Identification
In this study, based on 10 ppm of the error thresholds, the orthogonal partial least squares discrimination analysis (OPLS-DA) indicated that a total of 918 metabolites were identified in PubChem, including 565 metabolites in the positive ion mode and 353 metabolites in the negative ion mode (Supplementary Table 1 and Supplementary Table 2). PCA variances, score 2D plots, and score 3D plots of the serum metabolomics in ESI+ and ESI- modes were shown in Figure 1A–1F, which revealed the gathered well QC of each group under different ion modes, confirming the repeatability and stability of the method. Among the 918 metabolites, 337 metabolites with FC ≥ 2 or ≤ 0.5 (212 metabolites in the positive ion mode and 125 metabolites in the negative ion mode) were selected as primary DMs; the detailed information on 337 primary DMs was shown in Supplementary Table 3. The heatmaps of all compounds, classes and col-row clusters were shown in Figure 2A–2C, which involved 23 class compounds. Principal component analyses (PCA) variances, score 2D plots and score 3D plots. (A) Variance explained by each principal component in the positive ion mode; (B) Variance explained by each principal component in the negative ion mode; (C) PCA score 2D plot in the positive ion mode; (D) PCA score 2D plot in the negative ion mode; (E) PCA score 3D plot in the positive ion mode; (F) PCA score 3D plot in the negative ion mode. PC1, the first principal components; PC2, the second principal components; Percentage represents the variance of the data set explained by the principal components The heatmaps of all metabolites in two groups. (A) The heatmaps of the noted compounds; (B) The heatmaps of the compound class; (C) The heatmaps of the compound col-row_cluster. Horizontal represents sample groups, vertical represents metabolites, red represents upregulation and green represents downregulation

Metabolite Enrichment and Metabolic Pathway Analyses
337 DMs were mapped to KEGG metabolic pathways, and 143 KEGG pathways were obtained (142 KEGG pathways except ko01100 were shown in supplementary Table 4). The differential abundance (DA) score and rich factor of the top 20 pathways were shown in Figure 3A and 3B. It was shown that the tricarboxylic acid (TCA) cycle (ko00020) and steroid hormone biosynthesis (ko00140) were significantly enriched metabolic pathways when comparing SH vs blank control groups (p<0.05). Furthermore, 13 DMs were enriched in the steroid hormone biosynthesis, and 6 DMs were enriched in the TCA cycle (Figure 4A and 4B). The KEGG regulation network was shown in Figure 5A. In addition, DMs were also mapped to the small molecule pathway database (SMPDB), and 608 action pathways were obtained, of which the action pathways of ibuprofen and celecoxib were two major highlights of enrichment (Figure 5B). Differential abundance (DA) score and rich factor of the top 20 KEGG pathways. (A) DA score of the top 20 KEGG pathways; (B) Rich factor of the top 20 KEGG pathways. Vertical represents pathways in ascending order of p-value; the point size represents the number of metabolites enriched in pathways. The higher the DA and rich factor the more significant the enrichment Differential metabolites (DMs) in two KEGG pathways. (A) DMs enriched in the steroid hormone biosynthesis; (B) DMs enriched in the crtrate cycle. Horizontal represents sample groups, vertical represents metabolites, red represents upregulation, and green represents downregulation KEGG regulation network and SMPDB action pathways. (A) KEGG regulation network; (B) The top 20 SMPDB action pathways.Vertical represents pathways in ascending order of p-value; the point size represents the number of metabolites enriched in pathways.The higher the rich factor the more significant the enrichment


Identification of Significant Changes in Metabolites
Among the 337 DMs, the most enriched metabolites set included hormones and hormone-related compounds, glycerophospholipids (GP), organic acids and their derivatives, nucleotides and their metabolites, heterocyclic compounds, benzene and substituted derivatives, amino acids and their metabolites, fatty acyls, carboxylic acids and their metabolites, etc. To accurately understand the changes in metabolites, the top twenty DMs and the top ten upregulated and downregulated DMs were obtained by absolute Log2FC (Figure 6A and 6B). However, only 191 DMs can be annotated in HMDB, and 98 DMs can be enriched in KEGG pathways (78 of 98 DMs are enriched in metabolic pathways). After non-enriched metabolites were excluded, in the top ten upregulated and downregulated DMs, progesterone (MW0062186) and monoacylglycerols (MEDL02326) were the first upregulated (5.47E+2) and downregulated (1.36E-3) metabolites, respectively. The corrected top ten upregulated and downregulated DMs were shown in Table 5. Detailed information on the enriched 98 DMs was shown in supplementary Table 5. The top differential metabolites (DMs) in two groups. (A) The top twenty DMs with Log2FC; (B) The top ten upregulated and downregulated DMs with Log2FC Detailed information on the corrected top of ten upregulated and downregulated DMs Level: 1b represents a medium match with standard, MS1, RT and MS2; 2 represents a close match with MS1, RT and MS2; 3 represents a medium match with MS1, RT and MS2.
It is worth noting that progesterone is enriched in 14 KEGG pathways, including steroid hormone biosynthesis (ko00140), metabolic pathways (ko01100), neuroactive ligand-receptor interaction (ko04080), ovarian steroidogenesis (ko04913), prolactin signaling pathway (ko04917), aldosterone synthesis and secretions (ko04925), pathways in cancer (ko05200), oocyte meiosis (ko04114), progesterone-mediated oocyte maturation (ko04914), cortisol synthesis and secretion (ko04927), Cushing syndrome (ko04934), chemical carcinogenesis-receptor activation (ko05207), prostate cancer (ko05215), and breast cancer (ko05224); while monoacylglycerols (MG) are enriched in 7 KEGG pathways, including glycerolipid metabolism (ko00561), metabolic pathways (ko01100), thermogenesis (ko04714), regulation of lipolysis in adipocytes (ko04923), fat digestion and absorption (ko04975),and vitamin digestion and absorption (ko04977).
Discussion
SH represents the various pharmacological properties of HCT, including but not limited to anti-inflammatory, 11 antibacterial, 25 antiviral and anticancer. 26 Previous studies have shown that SH demonstrates promising potential in preventing obesity, 27 protecting against myocardial infarction 28 and neuronal damage. 7 However, the mechanisms underlying these effects remain largely unclear. LC-MS-based non-targeted metabolomics analyses have become increasingly important in exploring the action mechanisms of drugs, as it can simultaneously detect thousands of metabolites in a high-throughput manner. 29 Thus, in this study, we performed in-depth rat serum metabolomic analyses to identify SH-treatment-altered metabolites as compared with normal rats. A total of 191 DMs were annotated in the HMDB, and significant alterations in the metabolomic composition were observed in the SH group. These findings suggest that metabolic reprogramming occurs in the SH group, which exerts the preventive effect on some latent diseases and may be a compensatory mechanism for the action of SH.
Anti-inflammation and immune regulation are main mechanisms in SH treatment, which are related to both innate immunity and adaptive immunity. 30 Immune cells have the energy demands for their activation and effector functions by metabolic reprogramming, which is mainly influenced by steroid hormones that modulate immune and inflammatory responses through intracellular metabolic pathways, such as the tricarboxylic acid cycle and oxidative phosphorylation. 31 In this study, we observed significant upregulation of certain metabolites associated with the TCA cycle and steroid hormone biosynthesis in the SH group. Notably, progesterone, a metabolite derived from cholesterol, showed a 547-fold upregulation in the SH group, and adenosine-5′-triphosphate (ATP, MEDN1519) was upregulated by 47.4-fold. It is known that progesterone is involved in regulating both innate and adaptive immune responses and plays a crucial role in suppressing inflammation for maintaining immune homeostasis. 32 The effect of stimulating steroid hormone biosynthesis and inducing progesterone is a possible mechanism of SH in preventing diseases. Progesterone not only regulates the menstrual cycle and maintains pregnancy, but also prevents hyperplasia, atypical hyperplasia, and uterine endometrial cancer. 33 Multiple epidemiological studies indicate that there is a negative association between full-term pregnancies and the incidence of ovarian and endometrial cancer. 34 The reduced risk of ovarian or endometrial cancer is mainly due to the increase in progesterone and the decrease in oestrogen during pregnancy. 35 In clinic, the analogues of progesterone, such as medroxyprogesterone acetate (MPA) and megestrol acetate (MA), are used to treat endometrial and cervical cancers with promising results. 36 Regarding the significant upregulation of progesterone in the SH group, it is possible that SH can prevent sex hormone-related diseases, for example, obesity, endometrial hyperplasia, cancer, and polycystic ovary syndrome.
Lipid metabolism dysregulation in the body is a major risk factor for many metabolism-related diseases, 37 including diabetes, thyroid diseases, adrenal gland diseases, and cranial nerve diseases. In this study, we also observed significant downregulation of certain metabolites associated with glycerolipid metabolism (ko00561), glycerophospholipid metabolism (ko00564) and retrograde endocannabinoid signalling (ko04723) in the SH group. Notably, monoacylglycerols (MAGs) showed a 735-fold downregulation in the SH group with a 2-3-fold downregulation of some glycerophospholipid metabolites, such as 1,2-Diarachidoyl-sn-glycero-3-phosphocholine (MW0011863) and LPC (0:0/20:2, MEDP1330) which are involved in glycerophospholipid metabolism and retrograde endocannabinoid signalling. These pathways and their associated metabolites have been reported to cause lipid metabolism dysregulation leading to excessive production of too much ROS and inflammatory factors, which in turn damage tissue cells.38,39 In contrast, pathway analyses of DMs in the SH group demonstrated significant enrichment of several processes, including glutathione metabolism (ko00480), biosynthesis of cofactors (ko01240), ferroptosis (ko04216), and thyroid hormone synthesis (ko04918), which are regulated by glutathione (upregulated 8.94-fold), a protective metabolite on tissue injury. These results are consistent with previous studies indicating that SH can induce the browning of inguinal white adipose tissue by inhibiting ROS and ferroptosis. 27 These data indicate that the altered metabolites and their enriched functional pathways in the SH group not only prevent lipid metabolism dysregulation but also promote antioxidant protection against tissue injury, suggesting their possible use in the treatment of metabolism-related diseases.
It should be acknowledged that this study has some limitations, especially the absence of disease-related and small-sample animal experiments. Further animal-related experiments and clinical trials are needed to confirm the effectiveness of this approach.
Conclusions
In summary, our analyses suggest that SH induces metabolic reprogramming by activating the steroid hormone biosynthesis pathway to prevent inflammation and maintain immunity homeostasis, while inhibiting lipid metabolism-related pathways to prevent lipid metabolism dysregulation. At the same time, SH also enhances antioxidant protection against tissue injury by activating the glutathione-regulated metabolic pathways. These characteristics of SH in regulating metabolic reprogramming may maximise clinical benefits while minimising toxicity. These results not only explain the reasons why SH exhibits various pharmacological properties but also expand its application scope in preventing diseases, providing a possible theoretical basis for the future use of SH.
Supplemental Material
Supplemental Material - Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases
Supplemental Material for Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases by Jin-cheng Du, Zhi-jian Long, Jia-huan Li in Natural Product Communications
Supplemental Material
Supplemental Material - Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases
Supplemental Material for Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases by Jin-cheng Du, Zhi-jian Long, Jia-huan Li in Natural Product Communications
Supplemental Material
Supplemental Material - Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases
Supplemental Material for Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases by Jin-cheng Du, Zhi-jian Long, Jia-huan Li in Natural Product Communications
Supplemental Material
Supplemental Material - Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases
Supplemental Material for Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases by Jin-cheng Du, Zhi-jian Long, Jia-huan Li in Natural Product Communications
Supplemental Material
Supplemental Material - Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases
Supplemental Material for Rat Serum Metabolomics Reveals a Metabolic Reprogramming Mechanism of Sodium Houttuyfonate in Preventing Diseases by Jin-cheng Du, Zhi-jian Long, Jia-huan Li in Natural Product Communications
Footnotes
Acknowledgments
We thank Henan University for providing the experimental platform for this study, the Wuhan Metware Bio. Co., Ltd for detection and analysis of non-targeted serum metabolomics, and Prof. Shao-feng Duan and Prof. Yan-ming Wang for editing this manuscript.
Ethical Considerations
The experimental protocol was approved by the Medical Ethics Committee of Henan University (authorization No. HUSAM 2024-168).
Consent to Participate
There are no human subjects in this article and informed consent is not applicable.
Funding
The authors received no financial support for the research, authorship and/or publication of this article.
Declaration of conflicting interests
The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Data Availability Statement
The data related to this study can be requested from the corresponding author.
Trial Registration
This article does not contain any clinical trials.
Statement of Human and Animal Rights
We confirm that guidelines on animal rights and treatment have been met and any details of approval obtained are indicated within the text of the submitted manuscript.
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References
Supplementary Material
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