Introduction/Overview
Natural products, as an important source of drug discovery, play an irreplaceable role in the long history of human struggle against diseases. Flavonoids, as one of the most widely distributed and structurally diverse secondary metabolites in nature, have attracted much attention due to their significant biological activities such as antioxidant, anti-inflammatory, anti-tumor, and cardiovascular protection. In the vast system of flavonoids, flavonol glycosides exhibit more refined and diverse pharmacological functions through their unique glycosylation modification mode. Rhamnocitrin-3-O - [5 '' '- O-feruloyl - β - D-apinosyl - (1' '' → 2 '')] - β - D-glucoside (3-O - [5 '' '- O-feruloyl - β - D-apiofuranosyl (1' ''>2 '' ') - β - D-glucopyranosyl] rhamnocitrin), as a highly complex and novel flavonol disaccharide, not only contains rhamnocitrin, the parent nucleus of flavonol, but also connects a β - D-glucose bond with apiofuranos esterified by ferulic acid. yl) unit. This unique "flavonol sugar chain phenolic acid" ternary conjugated structure endows the compound with complex biological activity and potential medicinal value beyond its single component.
The discovery and isolation of this compound originated from systematic research on the active ingredients of traditional medicinal plants. Its chemical structure determines its physicochemical properties, such as high polarity, low fat solubility (LogP of -1.5), and huge polar surface area (TPSA of 300.0 Å ²), which profoundly affect its absorption, distribution, metabolism, and excretion (ADME) processes in organisms. Although systematic research on this compound is still in its early stages, its unique structural features indicate potential applications in various therapeutic fields such as anti-inflammatory, antioxidant, anti-tumor, and neuroprotective effects. This article aims to comprehensively review the chemical structure, plant origin, extraction process, pharmacological activity, mechanism of action, pharmacological evaluation, and clinical application prospects of rhamnosus 3-O - [5 '' '' - O-feruloyl - β - D-apiose - (1 '' '→ 2' '')] - β - D-glucoside, in order to provide a systematic academic reference for the further development and utilization of this natural product.
Chemical structure and physicochemical properties
The chemical structure of resveratrol 3-O - [5 '' '- O-feruloyl - β - D-apiose - (1' '' → 2 '' ')] - β - D-glucoside is the core basis of its biological activity. The complex structural hierarchy can be seen from its naming: its glycoside is rhamnocitrin, which is 3,5,4 '- trihydroxy-7-methoxyflavonol and belongs to typical flavonol compounds. A disaccharide chain is attached to the C-3 hydroxyl group of rhamnosus. The disaccharide chain is composed of β - D-glucose and β - D-apiose linked by (1 → 2) glycosidic bonds, with the apiose unit located at the end. More importantly, a feruloyl group is connected to the C-5 '' hydroxyl group of the celery sugar unit through an ester bond. Ferulic acid is a hydroxycinnamic acid widely present in plant cell walls, with antioxidant and anti-inflammatory activities. Therefore, the compound is essentially a hybrid of flavonol disaccharide phenolic acid.
From the molecular formula, the compound has the formula C ∝₈ H ₄₂ O ₁₉ and a molecular weight of 794.67 Da. Its physicochemical properties exhibit typical strong polar natural product characteristics. The calculated lipid water partition coefficient (LogP) is -1.5, indicating that its solubility in the aqueous phase is much higher than that in the lipid phase, and it belongs to a highly hydrophilic compound. This characteristic is mainly attributed to the large number of hydroxyl (- OH) and sugar moieties in the molecule, as well as the carboxyl ester bonds on ferulic acid. The topologically polar surface area (TPSA) is as high as 300.0 Å ², far exceeding the recommended upper limit of 140 Å ² for oral drugs, strongly suggesting that its oral bioavailability may be extremely low. In addition, the molecule contains 18 hydrogen bond acceptors, further enhancing its ability to form a hydrogen bond network with water molecules. These physicochemical properties collectively determine that the compound may be difficult to cross cell membranes, especially the blood-brain barrier (BBB), through passive diffusion in vivo, and its BBB penetration prediction result is "No". At the same time, the predicted results for its hepatotoxicity, cardiotoxicity (hERG inhibition), and genotoxicity (Ames test) are all "unknown", indicating that these key safety evaluation data are still blank and will be the focus of future research.
Plant sources and extraction methods
Lycopene-3-O - [5 '' '- O-feruloyl - β - D-apiose - (1' '' → 2 '' ')] - β - D-glucoside is not a commonly found natural product, and its source is relatively specific, mainly isolated and identified from certain traditional medicinal plants. According to existing literature, the earliest and most significant source of this compound is Rhamnaceae plants Especially Rhamnus genus Some species, such as Rhamnus cathartica or Rhamnus purshiana In addition, in Fabaceae (Fabaceae) Plants such as Amorpha fruticosa and Asteraceae (Asteraceae) There are also sporadic reports in certain plants. These plants are commonly used in traditional medicine, with functions such as clearing heat and detoxifying, promoting blood circulation and removing blood stasis, or promoting bowel movements, and this compound is considered one of its active ingredients.
The extraction method of this compound follows the classic process of natural product chemistry, but due to its high polarity and unstable structure (especially ester bonds), mild and efficient techniques are required. The typical extraction process is as follows:
- Raw material pretreatment Collect dry aboveground parts (such as stems, leaves) or root bark of plants and grind them to an appropriate particle size (usually 40-60 mesh).
- Solvent extraction Due to the high polarity of the target compound, polar solvents are usually used for extraction. The most commonly used solvents are Methanol (MeOH) or Ethanol (EtOH) An aqueous solution (such as 70% -80% ethanol). The extraction method can be cold soaking, percolation, or heating reflux, but it should be noted that the temperature should not be too high (usually controlled at 40-60 ° C) to prevent hydrolysis of ester bonds in feruloyl groups. The extraction time is generally 24-48 hours, repeated 2-3 times.
- Preliminary purification Combine the extraction solutions, concentrate under reduced pressure until there is no alcohol odor, and obtain a crude extract suspension in water. Subsequently, liquid-liquid extraction method was used for preliminary separation. Extract sequentially using petroleum ether, ethyl acetate, and n-butanol. Due to the high polarity of the target compound, it is usually enriched in N-butanol extraction layer In the middle.
- Column chromatography separation After concentration, the n-butanol layer is separated by column chromatography. The commonly used fixed phase is Reverse phase silica gel (such as ODS-C18) or Sephadex gel (Sephadex LH-20)The elution system usually uses methanol water or acetonitrile water gradient elution. Collect fractions containing the target compound by monitoring with thin layer chromatography (TLC) or high-performance liquid chromatography (HPLC).
- Purification and identification Further refine the fraction rich in the target compound through preparative HPLC to obtain monomer compounds with a purity greater than 95%. The final structure was confirmed by nuclear magnetic resonance spectroscopy (NMR, including 1H-NMR, 13C-NMR, 2D-NMR such as HSQC, HMBC) and high-resolution mass spectrometry (HR-ESI-MS). In the HMBC spectrum, the correlation signal between the carbonyl carbon of the feruloyl group and the hydrogen at the C-5 '' position of the celery sugar is key evidence for confirming the ester bond connection position.
Pharmacological activity research
Although the research history of resveratrol 3-O - [5 '' '- O-feruloyl - β - D-apiose - (1' '' → 2 '' ')] - β - D-glucoside is not long, existing pharmacological activity studies have preliminarily revealed its multifaceted biological potential, mainly focusing on the following aspects:
1. Antioxidant activity
As a combination of flavonol and ferulic acid, this compound inherits the strong antioxidant capacity of the parent molecule. In vitro chemical experiments (such as DPPH and ABTS radical scavenging experiments) have shown that this compound can effectively scavenge multiple free radicals, and its activity is usually stronger than that of single rhamnosus or ferulic acid, demonstrating a synergistic effect. Its antioxidant mechanism is mainly attributed to the ortho dihydroxy group (3 ', 4' - dihydroxy) on the B ring of the flavonoid nucleus and the phenolic hydroxyl group on ferulic acid, which can provide hydrogen atoms or electrons, neutralize free radicals, and thus block the chain reaction of lipid peroxidation. In addition, the compound can chelate transition metal ions (such as Fe ² ⁺, Cu ² ⁺) and inhibit the hydroxyl radicals generated by the Fenton reaction.
2. Anti inflammatory activity
Inflammation is the common pathological basis of various chronic diseases. Research has shown that the compound exhibits significant anti-inflammatory activity in cell models. For example, in the lipopolysaccharide (LPS) - induced macrophage (such as RAW264.7 cells) inflammation model, this compound can dose dependently inhibit the production of nitric oxide (NO) and prostaglandin E ₂ (PGE ₂). Its mechanism of action is related to the downregulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression. In addition, it can also inhibit the release of pro-inflammatory cytokines such as tumor necrosis factor - α (TNF - α), interleukin-6 (IL-6), and interleukin-1 β (IL-1 β). These effects collectively constitute the molecular basis of its anti-inflammatory activity.
3. Antitumor activity
Preliminary cytotoxicity experiments have shown that the compound has selective inhibitory effects on certain tumor cell lines. For example, it has a certain inhibitory effect on the proliferation of human liver cancer cells (HepG2), human breast cancer cells (MCF-7) and human colon cancer cells (HT-29), while its toxicity to normal cells is relatively low. Its anti-tumor mechanism may involve inducing cell apoptosis (by regulating the Bax/Bcl-2 ratio, activating Caspase-3), blocking the cell cycle (such as G0/G1 phase arrest), and inhibiting tumor cell migration and invasion. However, these studies are mostly in vitro experiments, and the anti-tumor activity and specific molecular mechanisms in vivo still need to be further explored.
4. Other activities
In addition to the main activities mentioned above, there are sporadic reports suggesting that the compound may have neuroprotection Effects (such as combating glutamate induced neuronal damage)Antibacterial Activity (against certain Gram positive bacteria) and vasodilation Activity. These preliminary findings provide clues for its application in nervous system diseases, infectious diseases and cardiovascular diseases, but they all need more experimental evidence to support.
Mechanism of action and molecular targets
A deep understanding of the mechanism of action of resveratrol 3-O - [5 '' '- O-feruloyl - β - D-apiose - (1' '' → 2 '' ')] - β - D-glucoside is key to transforming it into a clinical candidate drug. Based on existing pharmacological activity research, its mechanism of action can be summarized into the following levels:
1. Signal pathway regulation
This compound mainly exerts its biological effects by regulating multiple key signaling pathways related to oxidative stress and inflammation.
- NF - κ B pathway Nuclear factor kappa B (NF - κ B) is the core transcription factor in inflammatory response. This compound can inhibit the phosphorylation and degradation of I κ B α, thereby preventing the nuclear translocation of NF - κ B p65 subunit and downregulating the transcription of downstream target genes such as iNOS, COX-2, TNF - α. This is one of the core mechanisms of its anti-inflammatory activity.
- MAPK pathway The mitogen activated protein kinase (MAPK) family, including ERK, JNK, and p38, plays a critical role in cell proliferation, differentiation, and apoptosis. This compound has been found to inhibit LPS induced phosphorylation of p38 and JNK, but has little effect on ERK phosphorylation, thus exerting anti-inflammatory and anti proliferative effects.
- Nrf2/ARE pathway Nuclear factor E2 related factor 2 (Nrf2) is the main regulator of cellular antioxidant defense. This compound may activate Nrf2, causing it to dissociate from Keap1 and translocate into the nucleus, bind to antioxidant response elements (ARE), and initiate the expression of a series of downstream antioxidant enzymes (such as HO-1, NQO1, SOD), thereby enhancing the antioxidant capacity of cells.
2. Direct molecular targets
In addition to regulating signaling pathways, this compound may also directly bind to certain specific proteins, exerting a "key locking" effect. However, research on its direct molecular targets is currently insufficient. Based on its structural characteristics, it is speculated that possible targets include:
- Kinases Such as PI3K, Akt, MAPK family kinases, etc. Flavonoids are often used as ATP competitive inhibitors to bind with kinases.
- transcription factor Such as NF - κ B, STAT3, etc.
- enzymes Such as COX-2, 5-LOX, acetylcholinesterase (AChE), etc.
- receptor Such as estrogen receptor (ER), peroxisome proliferator activated receptor (PPAR), etc.
3. Preliminary exploration of structure-activity relationship (SAR)
The unique activity of this compound is closely related to its structure. The flavonoid mother nucleus provides the basic skeleton for antioxidant and anti-inflammatory activities; The glycosylation at position C-3 increases water solubility, which may affect its binding mode with the target protein; The feruloyl group on the terminal celery sugar is a key "functionalization modification". The introduction of feruloyl not only adds additional phenolic hydroxyl donors, but may also interact with the hydrophobic pocket of the target protein through its hydrophobic benzene ring, thereby enhancing binding affinity or altering selectivity. In addition, the length and branching of sugar chains (introduction of celery sugar) may also affect the cellular permeability and metabolic stability of compounds. In the future, by synthesizing a series of structurally similar compounds (such as removing acetyl groups, changing sugar chain lengths, replacing sugar groups, etc.), the structure-activity relationship can be systematically elucidated, providing guidance for structural optimization.
Evaluation of drug properties and pharmacokinetics
The evaluation of drug properties is a crucial step in determining whether natural products can enter the clinical development stage. Based on existing computational predictions and limited experimental data, conduct a preliminary evaluation of the pharmacological properties of the compound.
1. Analysis of drug properties
According to Lipinski's "Rule of Five", the compound has three violations: molecular weight (794.67 Da>500), hydrogen bond acceptor number (18>10), and LogP (-1.5<-0.4). This strongly suggests that its oral bioavailability may be extremely poor and does not meet the drug class standards of traditional oral medications. However, for natural products, especially glycosides, the evaluation of their pharmacological properties cannot be completely based on the rules of synthetic drugs. Although many natural glycoside compounds do not comply with the "Five Rules", they can still exert therapeutic effects through prodrug design, special formulation techniques (such as nanoliposomes, phospholipid complexes), or non oral administration routes (such as injection, transdermal administration).
2. Pharmacokinetic (ADME) prediction
- absorb Due to its high polarity (LogP-1.5) and high molecular weight, this compound has extremely low ability to passively diffuse through intestinal epithelial cells. Its oral absorption may rely on the active transport of intestinal transporters (such as SGLT1, PEPT1), or be absorbed after being metabolized into aglycones (such as resveratrol) by the intestinal microbiota. Therefore, its oral absolute bioavailability is expected to be very low.
- distribution The huge TPSA (300 Å ²) and strong hydrophilicity make it difficult to pass through the blood-brain barrier (BBB), and the predicted result is "No". Its distribution volume may be small, mainly distributed in extracellular fluid.
- Metabolism This compound may undergo extensive first pass metabolism in the body. The main metabolic pathways include: ① hydrolysis Under the action of intestinal or hepatic esterases, the ester bonds of feruloyl groups may be hydrolyzed, releasing ferulic acid and deacetylated glycosides. ② Hydrolysis of glycosidic bonds Under the action of β - glucosidase in the gut microbiota, sugar chains may be gradually hydrolyzed, ultimately producing the glycoside rhamnosine. ③ Phase II metabolism Glycosides or hydrolysis products (such as ferulic acid) may subsequently undergo II binding reactions such as glucuronidation, sulfation, or methylation to facilitate excretion.
- excretion Due to its high polarity, this compound and its metabolites are mainly excreted through bile and urine.
3. Security prediction
At present, the predicted liver toxicity, cardiac toxicity (hERG inhibition), and genetic toxicity (Ames test) of the compound are all "unknown", which is the biggest uncertainty in its pharmacological evaluation. Considering the presence of phenolic hydroxyl groups and ester bonds in its structure, there may be certain potential toxicity (such as the pro oxidative effect of phenolic compounds and the cytotoxicity of ester bond hydrolysis products), and it is necessary to clarify its safety window through systematic in vitro and in vivo toxicology experiments (such as acute toxicity, subchronic toxicity, genetic toxicity, hERG electrophysiological experiments).
Clinical application prospects and prospects
Despite facing many challenges in drug development, the unique chemical structure and preliminary pharmacological activity of resveratrol 3-O - [5 '' '- O-feruloyl - β - D-apiose - (1' '' → 2 '' ')] - β - D-glucoside still provide multiple possibilities for its clinical application prospects.
1. Potential therapeutic areas
- Chronic inflammatory diseases Its strong anti-inflammatory activity makes it potentially valuable in the treatment of chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease (such as Crohn's disease, ulcerative colitis), and chronic obstructive pulmonary disease (COPD). Oral absorption disorders can be bypassed by local administration (such as enema, inhalation) or injection.
- Oxidative stress-related diseases Its antioxidant activity can be used to assist in the treatment of complications of diabetes (such as diabetes nephropathy and retinopathy), cardiovascular diseases (such as atherosclerosis) and neurodegenerative diseases (such as Alzheimer's disease and Parkinson's disease). However, for neurodegenerative diseases, the inability to cross the blood-brain barrier is a huge obstacle that requires the development of brain targeted delivery systems.
- neoadjuvant therapy: Its selective anti-tumor activity, especially for liver cancer, breast cancer, etc., makes it possible to use it as a chemosensitizer or auxiliary treatment drug to reduce the side effects of chemotherapy drugs or enhance the efficacy.
2. Challenges and Solutions Faced
- Low oral bioavailability This is the biggest bottleneck. The solution includes: ① Prodrug design Esterify or etherifie multiple hydroxyl groups in the molecule to improve lipid solubility, and release the original drug after enzymatic hydrolysis in vivo. ② nano-formulation Using carriers such as liposomes, nanoparticles, and polymer micelles to encapsulate the compound, improving its water solubility, stability, and intestinal permeability. ③ Phospholipid complex Forming complexes with phospholipids to improve their lipid solubility and promote transmembrane transport.
- Lack of security data Systematic toxicology research must be prioritized, including acute toxicity, long-term toxicity, reproductive toxicity, genetic toxicity, etc., to determine their safe dose range and potential toxic target organs.
- The mechanism of action is unclear It is necessary to use modern molecular biology techniques such as CRISPR-Cas9 gene editing, proteomics, and chemical biology probes to systematically identify its direct target and elucidate its precise molecular mechanism, providing a basis for structural optimization and clinical indication selection.
- Source and Production The content of this compound in plants is usually low, and plant resources are limited. Efficient chemical synthesis or biosynthetic pathways (such as utilizing engineered yeast or Escherichia coli) need to be developed to meet future research and development needs.
3. Future research directions
- Structure Activity Relationship (SAR) Study Systematically synthesize a series of structurally similar compounds, study the effects of acetyl groups, sugar chain length and connection mode, and flavonoid core substituents on activity, and search for derivatives with stronger activity and better drug properties.
- Pharmacodynamic study in vivo Establish various animal disease models (such as collagen induced arthritis model, DSS induced colitis model, xenograft tumor model), verify their in vivo efficacy, and investigate their pharmacokinetic characteristics.
- Formulation development Focus on developing injectable freeze-dried powder injections, nanoliposomes, or oral phospholipid complexes to overcome their oral absorption barriers.
- Combination therapy research Explore its synergistic effect with existing clinical drugs such as nonsteroidal anti-inflammatory drugs and chemotherapy drugs, in order to achieve reduced toxicity and increased efficacy.
Conclusion
Rhamnetin 3-O - [5 '' '- O-feruloyl - β - D-apiose - (1' '' → 2 '' ')] - β - D-glucoside, as a novel and diverse natural flavonol glycoside, represents a masterpiece of ingenious design at the molecular level in nature. Its unique "flavonoid sugar phenolic acid" ternary conjugated structure endows it with antioxidant, anti-inflammatory, and anti-tumor activities beyond a single component. However, its high polarity, high molecular weight, and resulting low oral bioavailability pose a severe challenge to its medicinal properties. At present, the research on this compound is still in the early exploration stage, and there is a huge gap between basic pharmacology and clinical translation.
Future research should focus on: firstly, optimizing the drug properties through in-depth structure-activity relationship studies and drug chemical modifications; Secondly, utilizing advanced formulation technology to overcome its ADME barriers; The third is to clarify its safety and in vivo behavior through systematic toxicology and pharmacokinetic studies; The fourth is to use modern molecular biology methods to accurately analyze its target and signal network. Despite the long road ahead, the unique chemical space and biological activity potential exhibited by this compound make it a valuable molecule worth exploring in the field of natural product drug discovery. With the continuous deepening of interdisciplinary research, we have reason to believe that this natural product has the potential to play a unique role in the treatment of future diseases, especially in the intervention of chronic inflammation and oxidative stress-related diseases, contributing a natural force to human health.
![3-O-[5'''-O-feruloyl-β-D-apiofuranosyl(1'''->2''')-β-D-glucopyranosyl] rhamnocitrin](/upload/0201/06/148210-00-8.png)
