Introduction/Overview
Inflammation is the core defense response of the body to injury or infection. However, uncontrolled chronic inflammation is the common pathological basis for many diseases such as arthritis, metabolic syndrome, neurodegenerative diseases, and tissue fibrosis. Therefore, the development of efficient and low toxicity anti-inflammatory drugs has always been a key focus in the field of drug research and development. In traditional medicine, the treasure trove of plant medicines provides an inexhaustible source for modern drug discovery. Darutoside, a diterpenoid compound isolated from the traditional anti rheumatic herb Darutoside, has attracted much attention in recent years due to its excellent multi-target anti-inflammatory activity. Its CAS number is 59219-65-7. Research has confirmed that Pixiu glycoside not only has significant anti-inflammatory and analgesic effects, but also promotes wound healing and regulates immune response, especially in models of inflammatory diseases such as acute gouty arthritis, showing good therapeutic potential. Compared to the potential gastrointestinal and cardiovascular risks associated with traditional nonsteroidal anti-inflammatory drugs (NSAIDs), hesperidin exhibits superior safety characteristics, making it an ideal candidate molecule for developing novel anti-inflammatory therapies. This article aims to systematically review the chemical properties, plant sources, pharmacological activities, mechanisms of action, medicinal properties, and clinical application prospects of salidroside, in order to provide comprehensive scientific references for the in-depth research and development of this natural product.
Chemical structure and physicochemical properties
Pixiu glycoside is a tetracyclic diterpenoid glycoside compound. Its molecular formula is C26H36O9 and its molecular weight is 484.6300. Structurally, its glycoside component is a diterpene with a characteristic skeleton (ent kaurane type or related type), which is connected to a molecule of glucose through an oxygen glycosidic bond at a specific position (usually C-19 position) to form a glycosidic structure. This glycosylation modification has a critical impact on its water solubility and biological activity.
Based on computational chemistry and experimental data, the physicochemical parameters related to the pharmacological properties of Pixiu glycoside are as follows: its lipid water partition coefficient (LogP) is 1.7579, indicating that the compound has moderate lipophilicity and is conducive to transmembrane absorption. The topological polar surface area (TPSA) is 139.84 Å ², which is relatively high and mainly attributed to the multiple hydroxyl groups in the molecule and oxygen atoms on the sugar ring, which affect its solubility and membrane permeability. The predicted value of its water solubility is 0.3198 mg/mL, which belongs to the range of slightly soluble to soluble. The presence of glycosides significantly improves its hydrophilicity. In terms of safety prediction, Pixiu glycoside exhibits good characteristics: its ability to cross the blood-brain barrier (BBB) is predicted to be "low", indicating a lower risk of central nervous system side effects; There is no significant inhibitory potential on hERG potassium channels (predicted as' no '), indicating a low risk of inducing QT interval prolongation in the heart; The Ames test predicted a result of 0.0, indicating that it may not be mutagenic. These preliminary pharmacological parameters have laid a favorable chemical foundation for the subsequent development of salidroside.
Plant sources and extraction methods
Pixiu glycosides are mainly derived from plants in the Asteraceae family, with the most famous being the traditional Chinese medicine "Pixiu grass". The dried aboveground parts of Siegebeeckia orientalis L., S. pubescens Makino, or S. glabrescens Makino have the effects of dispelling wind and dampness, promoting joint development, and detoxifying in traditional Chinese medicine theory. They are commonly used to treat rheumatism, rheumatism, muscle weakness, and ulcers. Pixiu glycoside is considered one of the main active ingredients that exert anti-inflammatory and analgesic effects.
The extraction and separation of Pixiu glycosides from plant materials usually follow the following process: first, dry Pixiu grass is crushed, and suitable solvents (such as methanol, ethanol, or aqueous ethanol) are used for reflux extraction or ultrasound assisted extraction. The extract is concentrated under reduced pressure to obtain a crude extract. Subsequently, preliminary enrichment was carried out using macroporous adsorption resin column chromatography, with water ethanol gradient elution commonly used. Hesperidin usually appears in the elution sites of medium to high concentrations of ethanol. Further purification relies on techniques such as normal phase silica gel column chromatography, reverse phase silica gel column chromatography (such as ODS-C18), and high performance liquid chromatography (HPLC). Modern separation techniques such as high-speed countercurrent chromatography (HSCCC) have also been successfully applied to the efficient preparation and separation of paeoniflorin. The structure can be confirmed by nuclear magnetic resonance (NMR), mass spectrometry (MS), and comparison with standard samples. To ensure the sustainability and controllable quality of resources, research has also been conducted on the biosynthetic pathway of salidroside and related studies on plant cell culture production.
Pharmacological activity research
Numerous preclinical studies have confirmed that paeoniflorin has a wide range of pharmacological activities, centered around its powerful anti-inflammatory and immunomodulatory effects.
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Anti inflammatory and analgesic activity In various animal models of acute and chronic inflammation, Pixiu glycoside has shown significant effects. For example, in a rat paw edema model induced by carrageenan or Freund's complete adjuvant, oral administration of hesperidin can dose dependently inhibit swelling, and its effect is comparable to classical NSAIDs. In the second phase (inflammatory pain) of acetic acid-induced mouse writhing test and formalin test, hesperidin showed clear analgesic effects without addictive effects, suggesting its mechanism of action different from opioid drugs.
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Promote wound healing Pixiu glycoside can significantly accelerate wound closure in animals with full-thickness skin defects. Its function is not only reflected in shortening the healing time, but also in improving the quality of healing, promoting granulation tissue growth, collagen deposition, and re epithelialization. This healing promoting effect is closely related to its anti-inflammatory and regulatory repair related cytokines.
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Immune regulatory effect Pixiu glycoside has a regulatory effect on immune cell function. It can inhibit the release of inflammatory factors by overactivated macrophages, while promoting macrophage polarization towards the M2 phenotype with repair function. In autoimmune disease-related models, hesperidin has also shown the potential to regulate the balance of T cell subsets.
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The therapeutic effect on acute gouty arthritis This is a major highlight of the research on Pixiu glycoside. In a rat model of acute gouty arthritis induced by sodium urate crystals, oral administration of paeoniflorin can significantly reduce joint swelling, decrease local inflammatory cell infiltration, and alleviate pain. Its effects involve multiple inhibition of inflammasome activation, inflammatory cytokine storm, and oxidative stress.
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Other potential activities Preliminary studies also suggest that Pixiu glycoside may have an improving effect on chronic inflammation related fibrotic diseases such as liver fibrosis and pulmonary fibrosis, which is related to its anti-inflammatory properties and inhibition of abnormal fibroblast activation.
Mechanism of action and molecular targets
The pharmacological effects of Pixiu glycoside stem from its synergistic regulation of multiple inflammation related signaling pathways and molecular targets. Its action network is shown in the following figure:
flowchart TD
A[豨莶苷 Darutoside] --> B[核心作用：抑制NF-κB通路<br>（NFKB1）]
B --> C1[抑制促炎因子表达<br>（TNF, IL-6）]
B --> C2[下调炎症介质合成<br>（PTGS2/COX-2, NOS2/iNOS）]
A --> D[调节巨噬细胞极化]
D --> D1[促进M2修复型极化]
D1 --> D2[促进组织修复与伤口愈合]
A --> E[抑制炎症小体激活]
E --> E1[抑制CASP1（Caspase-1）]
E1 --> E2[减少IL-1β等成熟释放]
A --> F[调控疼痛感知]
F --> F1[抑制疼痛相关离子通道<br>（TRPV1, TRPA1）]
C1 & C2 & E2 --> G[综合效应]
F1 --> G
G --> H1[显著抗炎]
G --> H2[有效镇痛]
G --> H3[缓解急性痛风性关节炎]
D2 --> H4[促进伤口愈合]
The core mechanism can be explained as follows:
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Inhibition of NF - κ B signaling pathway This is the central link in the anti-inflammatory effect of Pixiu glycoside. NF - κ B is a key transcription factor that regulates the expression of numerous inflammatory genes. Pixiu glycoside can inhibit the activation of I κ B kinase (IKK), prevent the degradation of I κ B α, and thus block the transfer of NF - κ B (such as p65/p50 dimer) to the nucleus. As shown in the figure, this directly leads to a decrease in the expression of a series of pro-inflammatory mediators downstream, including TNF-α、IL-6 Waiting for cytokines, and Cyclooxygenase-2 (COX-2, encoded by PTGS2) and Inducible nitric oxide synthase (iNOS, encoded by NOS2)The downregulation of COX-2 reduces the production of pain and inflammatory mediators such as prostaglandin E2 (PGE2), while the inhibition of iNOS reduces tissue damage caused by excessive nitric oxide (NO).
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Regulating macrophage polarization As shown in the figure, Pixiu glycoside can regulate the transformation of macrophages from pro-inflammatory M1 type to anti-inflammatory and reparative M2 type. This process is partially achieved by inhibiting NF - κ B and STAT3 Signal pathway implementation. M2 macrophages secrete factors such as IL-10 and TGF - β, promoting angiogenesis and collagen synthesis, which is an important cellular basis for their promotion of wound healing.
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Inhibit inflammasome activation Activation of NLRP3 inflammasome is crucial in acute gout and other diseases. Pixiu glycoside has been shown to inhibit the assembly and activation of NLRP3 inflammasomes, thereby reducing Caspase-1（CASP1） The activation. Activated Caspase-1 is responsible for cleaving pro-IL-1 β and pro-IL-18 into mature, highly inflammatory forms. Pixiu glycoside effectively inhibits the release of IL-1 β through this pathway, which is particularly crucial for controlling acute attacks of gouty arthritis.
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Intervention in pain signal transduction The analgesic effect of Pixiu glycoside is related to its regulation of peripheral nociceptors. Research has shown that it can inhibit Transient receptor potential vanillic acid subtype 1 (TRPV1) and Transient receptor potential anchor protein subtype 1 (TRPA1) The activity of the channel. These two channels are important sensors for mediating thermal pain and chemical pain (such as pain sensitization caused by inflammatory mediators). By inhibiting these channels, hesperidin directly reduces the transmission of pain signals.
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Potential impact on COX-1 Although Pixiu glycoside selectively inhibits the expression of COX-2, it COX-1（PTGS1） The direct impact is relatively small, which may be one of the reasons why its gastrointestinal side effects are lower than traditional non selective NSAIDs.
Evaluation of drug properties and pharmacokinetics
Based on its good physicochemical properties, preliminary progress has been made in the pharmacological study of Pixiu glycoside.
pharmacokinetics Animal pharmacokinetic studies have shown that salidroside can be absorbed into the bloodstream after oral administration, but its absolute bioavailability needs further precise determination. Its distribution in the body conforms to the two compartment model, mainly distributed in tissues with abundant blood flow and inflammatory sites. Due to its high molecular weight and sugar content, its ability to cross the blood-brain barrier is limited, which is consistent with predictions, but also limits its direct effect on central nervous system inflammation. The metabolic pathways of paeoniflorin in the body mainly include phase I (such as hydroxylation) and phase II (such as glucuronidation and sulfation) reactions in the liver. The prototype drug and its metabolites are mainly excreted through the kidneys with urine, and some are excreted through bile and feces. Half life (t1/2) studies suggest that it has a moderate in vivo residence time, supporting once or twice daily dosing regimens.
safety evaluation Acute and long-term toxicity experiments have shown that hesperidin has a high safety window within the effective dose range. No significant liver or kidney toxicity or hematological abnormalities were observed. Of particular note, at therapeutic doses, its irritation to gastrointestinal mucosa is significantly lower than that of traditional NSAIDs such as indomethacin, which is related to its mechanism of selective inhibition of COX-2 and minimal impact on COX-1. The negative prediction of hERG inhibition and Ames test further supports its low risk of cardiac safety and genetic toxicity.
Formulation development challenges Although its water solubility is still acceptable, researchers are exploring novel drug delivery systems such as phospholipid complexes, solid dispersions, nanocrystals, or liposome encapsulation to further improve its oral bioavailability. These technologies aim to enhance their solubility, stability, and intestinal permeability.
Clinical application prospects and prospects
As a natural anti-inflammatory compound with multiple targets and high safety, Pixiu glycoside has broad clinical application prospects, but also faces challenges.
Potential application directions：
1. Rheumatoid immune diseases：Acute gouty arthritis It is one of its most promising indications. Based on its clear inhibitory effect on inflammasomes and sodium urate crystals induced inflammation, it can be developed as an oral or topical preparation for the acute phase treatment of gout. In addition, it also has therapeutic value for chronic inflammatory joint diseases such as rheumatoid arthritis and osteoarthritis.
2. Dermatology and Trauma Repair: Its anti-inflammatory and polarization promoting properties of M2 macrophages enable it to be used to treat chronic refractory wounds (such as diabetes foot ulcers, pressure ulcers), burns, specific dermatitis, psoriasis and other inflammatory skin diseases.
3. Other inflammation related diseases The efficacy has been demonstrated in preclinical models of diseases such as pulmonary fibrosis, liver fibrosis, and inflammatory bowel disease, and further exploration is warranted.
4. As a lead compound for structural optimization Pharmaceutical chemists can modify the aglycone or glycosyl portion of Pixiu glycoside to improve its pharmacokinetic properties, enhance target selectivity or efficacy, and thus develop more advantageous synthetic derivatives.
Challenges faced and future research directions：
1. Deep exploration of the mechanism of action Although it is known to act on multiple targets, the existence of an upstream, direct molecular target (such as a receptor or kinase) still needs to be explored using chemical biology methods (such as affinity fishing, molecular docking, and validation).
2. High level preclinical and clinical research At present, the data mainly comes from cell and animal models. It is necessary to complete systematic GLP toxicology research, establish pharmacokinetic/pharmacodynamic (PK/PD) models, and ultimately advance them to human clinical trials to confirm their safety and efficacy.
3. Quality Control and Large Scale Production Ensuring stable sources of raw medicinal materials, standardized extraction processes, and meeting the purity standards of final products are prerequisites for achieving industrialization. Synthetic biology or plant cell culture techniques may be long-term strategies to address resource issues.
4. Potential for combination therapy Exploring the combined use of Pixiu glycoside and existing anti-inflammatory drugs (such as low-dose colchicine and glucocorticoids) may produce synergistic effects, reducing their respective dosages and side effects.
Conclusion
Pixiu glycoside is a treasure discovered from the traditional Chinese medicine Pixiu grass, and its research perfectly embodies the translational medicine path from traditional experience to modern scientific verification. As a structurally clear and multi-target diterpenoid glycoside, Pixiu glycoside exerts strong anti-inflammatory, analgesic, healing promoting, and immune regulatory effects through multiple mechanisms such as inhibiting the NF - κ B pathway, regulating macrophage polarization, inhibiting inflammasomes, and pain related ion channels. It has also demonstrated excellent safety features in preclinical studies. Especially in the field of treating acute gouty arthritis, it provides new mechanisms of action and potential treatment options that are different from existing drugs. Although the successful translation of it into clinical drugs still requires overcoming challenges such as in-depth elucidation of mechanisms, clinical evaluation, and production processes, the solid research foundation already paints a bright future for its development. In the future, through interdisciplinary collaboration, Pixiu glycoside is expected to be developed into a new type of anti-inflammatory drug that originates naturally, has a novel mechanism of action, and is highly safe, benefiting a large number of patients with inflammatory diseases.
