Therapeutic effects of Siegesbeckia orientalis L. and its active compound luteolin in rheumatoid arthritis: network pharmacology, molecular docking and experimental validation.

ETHNOPHARMACOLOGICAL RELEVANCE: Rheumatoid arthritis (RA) is a common difficult disease with a high disability rate. Siegesbeckia orientalis L. (SO), a Chinese medicinal herb that is commonly used for treating RA in clinical practice. While, the anti-RA effect and the mechanisms of action of SO, as well as its active compound(s) have not been elucidated clearly. AIM OF THE STUDY: We aim to explore the molecular mechanism of SO against RA by using network pharmacology analysis, as well as the in vitro and in vivo experimental validations, and to explore the potential bioactive compound(s) in SO. METHODS: Network pharmacology is an advanced technology that provides us an efficient way to study the therapeutic actions of herbs with the underlying mechanisms of action delineated. Here, we used this approach to explore the anti-RA effects of SO, and then the molecular biological approaches were used to verify the prediction. We first established a drug-ingredient-target-disease network and a protein-protein interaction (PPI) network of SO-related RA targets, followed by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Further, we used lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and vascular endothelial growth factor-A (VEGFA)-induced human umbilical vein endothelial cell (HUVEC) models, as well as adjuvant-induced arthritis (AIA) rat model to validate the anti-RA effects of SO. The chemical profile of SO was also determined by using the UHPLC-TOF-MS/MS analysis. RESULTS: Network pharmacology analysis highlighted inflammatory- and angiogenesis-related signaling pathways as promising pathways that mediate the anti-RA effects of SO. Further, in both in vivo and in vitro models, we found that the anti-RA effect of SO is at least partially due to the inhibition of toll like receptor 4 (TLR4) signaling. Molecular docking analysis revealed that luteolin, an active compound in SO, shows the highest degree of connections in compound-target network; moreover, it has a direct binding to the TLR4/MD-2 complex, which is confirmed in cell models. Besides, more than forty compounds including luteolin, darutoside and kaempferol corresponding to their individual peaks were identified tentatively via matching with the empirical molecular formulae and their mass fragments. CONCLUSION: We found that SO and its active compound luteolin exhibit anti-RA activities and potently inhibit TLR4 signaling both in vitro and in vivo. These findings not only indicate the advantage of network pharmacology in the discovery of herb-based therapeutics for treating diseases, but also suggest that SO and its active compound(s) could be developed as potential anti-RA therapeutic drugs.

Metabolomics Reveals the Mechanisms for the Pulmonary Toxicity of Siegesbeckia orientalis L. and the Toxicity-Reducing Effect of Processing.

Siegesbeckia orientalis L. (SO) is a commonly used Chinese medicinal herb. It has long been used as a remedy in traditional Chinese medicine (TCM) for symptoms that resemble inflammatory joint disorders. However, it is slightly toxic. According to the TCM theory, processing can reduce the toxicity of the herbs. Here, we performed metabolomics to determine whether processing with rice wine reduces the toxicity of raw SO, and to explore the mechanisms underlying the raw SO-induced toxicity and the toxicity-reducing effect of processing. Our results showed that raw SO has long-term toxicity in rats. It significantly elevated the serum level of LDH and caused histopathological damages in the lung tissues. It is worth noting that the LDH level in the PSO group was lower than that in the raw SO group, and the damages in lung tissues were relatively mild in PSO-treated rats, suggesting that processing reduces the pulmonary toxicity of the raw. Moreover, a total of 32 significantly changed metabolites were identified. Based on the MetaboAnalyst pathway analysis, we found that two characteristic metabolic pathways including alanine, aspartate and glutamate metabolism and glycerophospholipid metabolism were only changed in the raw SO group, while histidine metabolism was only changed in the PSO group, which suggests that induction of oxidative stress contributes to raw SO-induced pulmonary toxicity, and free radical scavenging might be responsible for the toxicity-reducing effect of processing. Our data shed new light on how raw SO induces pulmonary toxicity and how the toxicity can be reduced by processing. This study not only provides scientific justifications for the traditional processing theory of SO, but also helps to optimize the processing protocol and the clinical drug combination of SO.

Standardized Siegesbeckia orientalis L. Extract Increases Exercise Endurance Through Stimulation of Mitochondrial Biogenesis.

Siegesbeckia orientalis has been reported to exhibit anti-allergic, anti-infertility, anti-inflammatory, anti-rheumatic, and immunosuppressive activities. However, there are very few studies describing its stimulatory effects on exercise capacity. This study elucidated whether S. orientalis extract (SOE) standardized to kirenol content can enhance exercise endurance by increasing mitochondrial biogenesis. SOE significantly improved the running distance and time in mice fed normal diet (ND) and high-fat diet (HFD). SOE also enhanced mitochondrial biogenesis by stimulating the mitochondrial regulatory genes including peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α), estrogen-related receptor α (ERRα), nuclear respiratory factor 1 (NRF-1), and mitochondrial transcription factor A (TFAM) in the skeletal muscles of ND and HFD mice. Furthermore, SOE upregulated the AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/PGC-1α/peroxisome proliferator-activated receptor delta (PPARδ) signaling pathway in the skeletal muscles of ND and HFD mice. Kirenol markedly increased adenosine triphosphate production and mitochondrial activity by stimulating the expression of markers of mitochondrial biogenesis and upregulating the AMPK/SIRT1/PGC-1α/PPARδ signaling pathway in L6 myotubes. These results show that SOE has the potential to be used to develop an exercise supplement capable of stimulating mitochondrial biogenesis through the AMPK/SIRT1/PGC-1α/PPARδ signaling pathway.

The complete chloroplast genome sequence of the medicinal plant Siegesbeckia orientalis L., the first in the genus Siegesbeckia.

Siegesbeckia orientalis L. is a plant with important medicinal and economic values. We reported the first complete chloroplast genome sequence of S. orientalis. This genome is 151,821 bp in length and comprises a large single-copy region of 83,540 bp, a small single-copy region of 18,225 bp and a pair of inverted repeat regions of 25,028 bp each. It encodes 138 genes, including 79 protein-coding genes, 27 tRNA genes, and 4 rRNA genes. The phylogenomic analysis showed that S. orientalis and Guizotia abyssinia were clustered together. This genomewill lay the foundation for the molecular discovery and phylogenomic study of this genus.