Introduction/Overview
Inflammation is a complex and sophisticated defense response of the body in response to infection, injury, or stress, which is precisely regulated by various cytokines, chemokines, and signaling pathways. However, when the inflammatory reaction is excessive or persistent, it will turn into a chronic inflammatory state and become the common pathological basis of many major diseases such as rheumatoid arthritis, atherosclerosis, neurodegenerative diseases and even cancer. Therefore, the development of efficient and low toxicity new anti-inflammatory drugs has always been a hot topic in pharmacological research. In traditional medicine, various medicinal plants are used to treat inflammation related diseases, indicating that they are rich in natural products with anti-inflammatory activity. Finding lead compounds from these natural molecules has become an important strategy in modern drug development.
In recent years, from the orchid plant Rhododendron（Cremastra appendiculata）A series of benzyl, phenanthrene, and phenolic glycosides identified through separation and identification have attracted widespread attention from researchers. Among them, a phenolic glycoside compound called 4- (glucose oxy) - cinnamic acid glucose oxy benzyl ester (Shancigusin I, CAS number: 1435488-35-9) has attracted much attention due to its multi-target anti-inflammatory potential demonstrated in preliminary studies. This compound has a unique structure and contains two glucose groups, suggesting that it may have a different mode of action than common nonsteroidal anti-inflammatory drugs (NSAIDs) or biologics. This article aims to systematically review the chemical properties, plant origin, pharmacological activity, mechanism of action, and pharmacological properties of Shancigusin I, and to provide prospects for its development as a novel anti-inflammatory candidate drug, in order to provide reference for in-depth research in related fields.
Chemical structure and physicochemical properties
Shancigusin I is a complex natural product of phenolic glycosides. Its chemical name clearly describes its core skeleton: a cinnamic acid fragment is connected to a benzyl alcohol fragment through an ester bond, and a glucose group is attached to the benzene ring of the benzyl alcohol and the cinnamic acid fragment, respectively. Specifically, its structure is 4- (β - D-glucopyranosyl) benzyl ester of 4- (β - D-glucopyranosyl) cinnamic acid.
The molecular formula of this compound is C28H34O15, with a molecular weight of 594.5660. The structure contains two highly hydrophilic glucose units, which directly determine its physicochemical properties. The calculated lipid water partition coefficient (LogP) is -0.2074, indicating that the compound exhibits overall hydrophilicity and tends to be distributed in the aqueous phase. Its topological polar surface area (TPSA) is as high as 225.060 Å ², mainly attributed to the numerous oxygen atoms (from sugar and ester bonds) in the molecule, further confirming its high polarity. The predicted water solubility value is 4.2827 (usually measured in mg/mL or log mol/L, indicating good water solubility), which is consistent with the characteristics of high TPSA and low LogP. These physicochemical parameters suggest that Shancigusin I may have limited solubility in conventional organic solvents, but should have good solubility in polar solvents such as water, methanol, and dimethyl sulfoxide (DMSO).
Plant sources and extraction methods
Shancigusin I mainly comes from the Rhododendron genus of the Orchidaceae family（Cremastra appendiculata (D. Don) Makino）。 The false bulb of this plant is called "Shanci mushroom" in traditional Chinese medicine, which has the effects of clearing heat and detoxifying, resolving phlegm and dispersing nodules. It is commonly used to treat diseases such as carbuncles, swelling, toxins, scrofula, phlegm nuclei, and insect snake bites. Its clinical application history suggests that it contains active ingredients such as anti-inflammatory and anti-tumor.
The extraction and separation of Shancigusin I from plant materials typically follow standard procedures in natural product chemistry. Firstly, the dried Rhododendron pseudobulbs are crushed and subjected to reflux extraction or cold soaking extraction using high concentration ethanol (such as 70% -95%) or methanol to fully extract polar and moderately polar components, including Shancigushin I. The crude extract obtained was concentrated under reduced pressure and suspended in water, followed by liquid-liquid extraction using organic solvents such as petroleum ether, ethyl acetate, and n-butanol. Due to the presence of two sugar groups and high polarity, Shancigusin I is mainly enriched in the n-butanol extraction site or aqueous layer.
Further purification relies on various chromatographic techniques. Large pore adsorption resins (such as D101, AB-8) are commonly used for column chromatography, with gradient elution using ethanol water systems of different concentrations to preliminarily enrich the target components. Subsequently, silica gel column chromatography, reverse phase silica gel column chromatography (such as ODS, C18), dextran gel column chromatography (such as Sephadex LH-20), and high-performance liquid chromatography (HPLC, preparative or semi preparative) were used for repeated separation and purification. By using nuclear magnetic resonance (NMR, including 1H NMR, 13C NMR, HSQC, HMBC, etc.), mass spectrometry (MS), and comparing with literature data, its chemical structure was finally determined. Modern technologies such as high-speed countercurrent chromatography (HSCCC) can also be used for efficient preparation of such polar natural products.
Pharmacological activity research
At present, pharmacological studies on Shancigusin I mainly focus on its anti-inflammatory effects, which have been validated in various in vitro inflammatory models.
1. Inhibition of inflammatory mediators:
Research has shown that Shancigusin I can significantly inhibit the excessive production of nitric oxide (NO) and prostaglandin E2 (PGE2) in macrophages (such as RAW 264.7 cells) induced by lipopolysaccharide (LPS). NO is synthesized by inducible nitric oxide synthase (iNOS, encoded by the NOS2 gene), while PGE2 is produced by the cyclooxygenase-2 (COX-2, encoded by the PTGS2 gene) pathway, both of which are key inflammatory mediators. The inhibitory effect of Shancigusin I shows a dose-dependent pattern, indicating that it can effectively intervene in early signaling and effector molecule synthesis of inflammation.
2. Regulation of pro-inflammatory cytokine expression:
In addition to inhibiting NO and PGE2, Shancigusin I can also downregulate the mRNA and protein expression levels of various pro-inflammatory cytokines. This includes tumor necrosis factor - α (TNF - α), interleukin-6 (IL-6), and interleukin-1 β (IL-1 β), among others. TNF - α and IL-6 are core factors that initiate and amplify the inflammatory cascade, while the maturation and release of IL-1 β depend on the activation of inflammasomes (involving CASP1). The extensive inhibitory effect of Shancigusin I on these key cytokines suggests its broad-spectrum anti-inflammatory potential.
3. Potential effects on inflammation related pain:
Given its anti-inflammatory activity, Shancigusin I may also have an impact on inflammatory pain. The targets predicted by research include TRPV1 and TRPA1, which are key sensors for sensing nociceptive stimuli such as heat and chemicals. They are sensitized in inflammatory environments and participate in the generation and transmission of pain signals. Although direct analgesic experimental data is yet to be supplemented, its regulation of the inflammatory microenvironment may indirectly alleviate pain hypersensitivity caused by inflammation.
4. Other potential activities:
As one of the active ingredients in Rhododendron, Shancigusin I may share certain biological activities with other similar compounds. For example, some benzyl compounds isolated from Rhododendron have shown anti-tumor, antioxidant, and neuroprotective effects. Whether Shancigusin I has these extended activities needs further exploration in future research.
Mechanism of action and molecular targets
The anti-inflammatory effect of Shancigusin I is not achieved through a single target, but is characterized by multi-target and multi pathway intervention, which is consistent with its broad-spectrum inhibitory effect in various inflammatory models. Current research suggests that its mechanism of action mainly involves the following key targets and signaling pathways:
1. Nuclear factor kappa B (NF - κ B) signaling pathway:
NF - κ B is a core transcription factor that regulates inflammatory responses. In the resting state, NF - κ B (usually referring to the p50/p65 dimer) binds to the inhibitory protein I κ B and exists in the cytoplasm. When cells are stimulated by LPS and other factors, I κ B is phosphorylated and degraded, allowing NF - κ B to enter the nucleus and initiate the transcription of numerous inflammatory genes such as iNOS, COX-2, TNF - α, IL-6, etc. Research has shown that Shancigusin I can inhibit the phosphorylation and degradation of I κ B α, thereby preventing the nuclear translocation and DNA binding activity of NF - κ B, and globally suppressing the expression of inflammatory mediators from upstream.
2. Signal transduction and transcription activator 3 (STAT3) pathway:
STAT3 is another important pro-inflammatory and pro survival signaling pathway. After binding to cytokines such as IL-6 and their receptors, JAK kinase can be activated, which in turn phosphorylates and activates STAT3. Activated STAT3 forms a dimer and enters the nucleus, promoting the expression of genes related to inflammation and cell proliferation. Shancigusin I has been shown to inhibit LPS induced STAT3 phosphorylation, thereby interrupting this pro-inflammatory signaling axis.
3. Regulation of inflammasome (NLRP3):
Inflammatory inflammasome is a multi protein complex within cells that is responsible for activating Caspase-1 (CASP1). Activated Caspase-1 cleaves inactive pro-IL-1 β and pro-IL-18 into mature, secreted active forms. The inhibitory effect of Shancigusin I on IL-1 β production may be related to its intervention in the assembly or activation of NLRP3 inflammasomes, although the specific mechanism still needs to be further elucidated.
4. Direct or indirect inhibition of enzyme activity:
Shancigusin I may have an impact on certain key inflammation related enzymes. For example, its inhibition of COX-2 (PTGS2) and iNOS (NOS2) expression has been demonstrated as previously mentioned. In addition, computational predictions suggest that it may interact with COX-1 (PTGS1), but the selectivity is not yet clear. The potential regulatory effects on TRPV1 and TRPA1 channels may involve interventions for pain and neurogenic inflammation.
In summary, Shancigusin I synergistically acts on key signaling pathways such as NF - κ B and STAT3, and may affect inflammasome activity and specific ion channels, forming a multi-level anti-inflammatory network that effectively inhibits excessive activation of inflammatory responses.
Evaluation of drug properties and pharmacokinetics
Based on computational chemistry and preliminary in vitro experimental data, the pharmacological properties of Shancigusin I can be preliminarily evaluated.
1. Analysis of the five principles of generic drugs (Lipinski rule):
The molecular weight of the compound (594.57) slightly exceeds the standard of 500; The calculated LogP (-0.21) is much smaller than 5, which meets the hydrophilicity requirement; The number of hydrogen bond donors (multiple hydroxyl groups on the sugar group) may exceed 5; There are also many hydrogen bond acceptors (numerous oxygen atoms). Therefore, Shancigusin I does not fully comply with the traditional five principles of class drugs, mainly due to its high polarity and molecular weight brought by its dual glycosidic structure. This is a common situation in natural products, which does not necessarily mean that they have no potential for drug development, but may indicate challenges in their oral bioavailability.
2. Prediction of absorption, distribution, metabolism, and excretion (ADME) characteristics:
* Absorption and oral bioavailability: High polarity, large TPSA, and multiple hydrogen bond donors/acceptors may lead to poor transmembrane permeability, especially weak ability to passively diffuse through intestinal epithelial cells. It is predicted that its oral bioavailability may be low. It may be necessary to improve through structural modifications (such as prodrug preparation) or non oral administration routes (such as injection, local administration).
* Distribution: The prediction shows that its ability to cross the blood-brain barrier (BBB) is "low", which is consistent with its high hydrophilicity and high molecular weight. This means that it may not easily enter the central nervous system, which may reduce central side effects for treating peripheral inflammatory diseases, but may be detrimental for treating neuroinflammation.
* Metabolism: As a glycoside compound, Shancigusin I is easily hydrolyzed by glycosidases (such as β - glucosidase) in the gastrointestinal tract or blood in vivo, removing the glucosyl group and generating the corresponding aglycone (4- (glucosyloxy) - benzyl cinnamate or simpler phenolic acid derivatives). The physicochemical properties of aglycones (increased LogP and decreased polarity) are completely different from the original drug, and their activity, metabolism, and toxicity need to be studied separately. This is the main pharmacokinetic issue faced by glycosidic natural products.
* Excretion: The high water solubility suggests that the prototype drug may be mainly excreted through the kidneys.
3. Preliminary safety assessment:
* HERG inhibition: The predicted result is' no ', indicating a low potential risk of causing QT interval prolongation in the heart, which is a favorable safety indicator.
* Genetic toxicity: The predicted value of Ames test is 0.0, indicating that it may not have mutagenicity, but it needs to be verified through experiments.
* Others: Further in vitro cytotoxicity experiments and in vivo acute and subacute toxicity studies are needed to comprehensively evaluate its safety.
In summary, Shancigusin I has clear multi-target anti-inflammatory activity, but its dual glycosidic structure poses challenges to drug development such as poor oral absorption and susceptibility to enzymatic metabolism. One of the future research focuses is how to improve its pharmacokinetic properties while retaining its pharmacological activity through pharmaceutical methods such as nano delivery systems, liposome encapsulation, or rational chemical modifications.
Clinical application prospects and prospects
As a natural anti-inflammatory lead compound with multi-target properties, Shancigusin I has broad clinical application prospects, but the development path is also full of challenges.
Potential application directions:
1. Chronic inflammatory diseases: Given its inhibition of pathways such as NF - κ B and STAT3, as well as its downregulation of various cytokines such as TNF - α, IL-6, and IL-1 β, Shancigushin I is expected to be used for the treatment of autoimmune or chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease (such as ulcerative colitis and Crohn's disease), psoriasis, etc. Its multi-target characteristics may bring synergistic therapeutic effects and reduce drug resistance caused by single target inhibition.
2. Inflammatory pain: If its regulatory effect on TRPV1/TRPA1 channels is experimentally confirmed, it may be developed for the treatment of neuropathic pain or inflammatory pain as an alternative or supplement to opioids or traditional NSAIDs.
3. Topical preparations for local use: Considering its possible poor oral absorption, it is a realistic and feasible direction to develop local topical preparations (such as cream, gel) for the treatment of skin inflammation (such as dermatitis, eczema) or joint local inflammation.
4. Combination therapy: As an adjuvant drug, when used in combination with existing anti-inflammatory drugs such as methotrexate and biologics, it may enhance efficacy or reduce the dosage and side effects of existing drugs.
Challenges and future research directions:
1. In depth mechanism research: At present, research on the mechanism of action still mainly focuses on the description of signaling pathways. Further research is needed to clarify whether it interacts directly with target proteins or indirectly through regulating upstream kinases or phosphatases. It is crucial to use techniques such as molecular docking and surface plasmon resonance (SPR) for target validation.
2. Comprehensive pharmacokinetic studies: Systematic in vivo pharmacokinetic experiments must be conducted to clarify its absorption, distribution, metabolism (especially the rate and location of glycoside hydrolysis), and excretion processes in different animal models, and to identify its main metabolites and their activities.
3. Structural optimization and derivative design: Structural modification is an inevitable path to address the shortcomings of its medicinal properties. For example, acylation and alkylation modification of glucose groups to improve lipid solubility and metabolic stability; Alternatively, the activity of its aglycone can be explored. If the aglycone activity is maintained or even enhanced, it can be directly optimized using aglycone as a lead compound.
4. Pharmacodynamics and safety evaluation in vivo: It is necessary to validate its in vivo anti-inflammatory effect in appropriate animal disease models, such as mouse collagen induced arthritis and DSS induced colitis models, and complete a systematic preclinical toxicological evaluation.
5. Pharmaceutical research: Develop suitable delivery systems, such as nanoparticles, microemulsions, liposomes, etc., to improve their bioavailability, targeting, and stability.
Conclusion
4- (Glucosoxy) - Cinnamoxybenzyl cinnamate (Shancigusin I) is a novel phenolic glycoside compound isolated from the traditional medicinal plant Rhododendron. Numerous in vitro studies have shown that it effectively downregulates the expression of various inflammatory mediators such as iNOS, COX-2, TNF - α, IL-6, IL-1 β, etc. by inhibiting key signaling pathways such as NF - κ B and STAT3. It exhibits multi-target and multi-level anti-inflammatory activity and has great potential as a novel anti-inflammatory lead compound. However, the high polarity, low permeability, and susceptibility to glycosidase metabolism brought about by its dual glycosidic structure constitute the main obstacles to its conversion into drugs. Future research needs to focus on elucidating its precise molecular mechanism of action and addressing its drug formulation issues. By optimizing its structure, innovating its dosage form, or exploring new routes of administration, it can promote its translation into clinical applications. Shancigusin I's research not only provides valuable candidate molecules for the development of new anti-inflammatory drugs, but also once again confirms that mining active natural products from traditional medicinal plants and using modern scientific technology for in-depth research and modification is an important source for discovering innovative drugs.
