Product name: 6-Hydroxykaempferol-3,6,7-triglucoside
Synonym name:
Catalogue No.: BPF2521
Cas No.: 145134-62-9
Formula: C₃₃H₄₀O₂₂
Mol Weight: 788.661
Botanical Source:
Physical Description:
Type of Compound: Flavonoids

Purity: 95%~99%
Analysis Method: HPLC-DAD or/and HPLC-ELSD
Identification Method: Mass, NMR
Packing: Brown vial or HDPE plastic bottle
The product could be supplied from milligrams to grams
Inquire for bulk scale.

For Reference Standard and R&D, Not for Human Use Directly.

Storage conditions：Short-term storage at 2~8℃, long-term storage at -20 ~ -80℃

Introduction/Overview

Natural products, as an important source of drug discovery, have long played an irreplaceable role in human health maintenance and disease treatment. Flavonoids, as the largest class of secondary metabolites in plants, have attracted much attention due to their extensive and significant biological activities, especially their antioxidant, anti-inflammatory, anti-tumor, and cardiovascular protective effects. Among numerous flavonoids, Kaempferol and its derivatives exhibit unique chemical and biological properties due to their multi hydroxyl substitution pattern in the core structure. 6-Hydroxykaempferol-3,6,7-tri-O-glucoside (6HK-3,6,7-Glc) is a highly glycosylated flavonol glycoside characterized by a glucose group attached to the C-3, C-6, and C-7 sites of the kaempferol nucleus, and an additional hydroxyl group at the C-6 site. This unique "polyhydroxy, polysaccharide based" structure endows the compound with excellent hydrophilicity and potential biological activity.

Although the distribution of 6HK-3,6,7-Glc in nature is relatively limited, mainly found in certain medicinal plants and vegetables, its potential in antioxidant stress-related diseases is gradually being revealed. Oxidative stress is the common pathophysiological basis of many chronic diseases, including cardiovascular diseases, neurodegenerative diseases, diabetes and its complications, skin aging and cancer. Therefore, the search for efficient and low toxicity natural antioxidants has always been a hot topic in pharmacological research. 6HK-3,6,7-Glc has shown great potential as a lead compound or dietary supplement due to its strong free radical scavenging ability and regulatory effects on multiple antioxidant signaling pathways. This article aims to systematically review the chemical structure, plant origin, extraction process, pharmacological activity, mechanism of action, pharmacological characteristics, and clinical application prospects of 6-hydroxykaempferol-3,6,7-tri-O-glucoside, in order to provide comprehensive academic references for the in-depth research and development of this natural product.

Chemical structure and physicochemical properties

The chemical structure of 6-hydroxykaempferol-3,6,7-tri-O-glucoside is based on the flavonol core - kaempferol. Kaempferol (3,5,7,4 '- tetrahydroxyflavone) itself has a classic C6-C3-C6 skeleton, consisting of two benzene rings (A and B) connected by an oxygen-containing heterocyclic ring (C ring). The structural specificity of 6HK-3,6,7-Glc is reflected in the following three aspects: firstly, an additional hydroxyl group (- OH) is introduced at the C-6 position of the A ring, making it a hexahydroxy substituted flavonol (6-hydroxykaempferol); Secondly, the hydroxyl groups at positions C-3, C-6, and C-7 are all replaced by β - D-glucose groups, forming a tri glycoside. This structure results in a molecular weight of 788.66 Da, far exceeding most small molecule flavonoid glycosides.

From the perspective of physical and chemical properties, this compound has extremely strong hydrophilicity. The calculated lipid water partition coefficient (LogP) is -1.8760, indicating that its solubility in the aqueous phase is much higher than that in the lipid phase. This characteristic is closely related to its topologically polar surface area (TPSA) of up to 368.81 Å ². TPSA reflects the total surface area of polar atoms (such as oxygen and nitrogen) and their connected hydrogen atoms in a molecule, and is commonly used to predict the transmembrane absorption capacity of molecules. A molecule with a TPSA greater than 140 Å ² is generally considered difficult to passively diffuse across the cell membrane. The TPSA value of 6HK-3,6,7-Glc far exceeds this threshold, indicating extremely low cell membrane permeability and potential challenges in oral bioavailability. However, its water solubility (4.9928) is good, which provides the possibility for its distribution in plasma and active transport through specific transporters such as glucose transporters GLUTs or sodium glucose cotransporters SGLTs. In addition, the compound's ability to penetrate the blood-brain barrier is predicted to be low, which limits its direct application in central nervous system diseases, but also reduces the potential risk of neurotoxicity. In terms of safety, preliminary predictions indicate a low risk of inhibition of hERG potassium channels (No), and the Ames test result is 0.0, suggesting no significant mutagenicity. This provides a favorable starting point for the safety evaluation of it as a candidate drug.

Plant sources and extraction methods

6-Hydroxykaempferol-3,6,7-tri-O-glucoside is not widely present in nature, and its sources are mainly concentrated in a few specific plant families and genera. The main sources of current literature reports include:

1. Asteraceae plants For example,Red flower (Carthamus tinctorius L.) The petals of 6HK-3,6,7-Glc are a classic source. As a traditional Chinese medicine for promoting blood circulation and removing blood stasis, safflower has a complex chemical composition, among which flavonoids are one of its main active ingredients. In addition,Saussurea involucrata The compound is also present in Asteraceae plants.
2. Cruciferous vegetables：Broccoli (Brassica oleracea var. italica) The tender buds and flower bulbs are rich in various flavonoid glycosides, among which 6HK-3,6,7-Glc is an important antioxidant component. This is also one of the reasons why the compound has attracted attention as a dietary antioxidant.
3. Other plants：Sophora japonica L、Ginkgo biloba L And some Leguminous plants It has also been reported in the leaves or seeds.

The choice of extraction method directly affects the yield and purity of 6HK-3,6,7-Glc. Given its high water solubility and thermal stability, traditional solvent extraction methods are still effective, but conditions need to be optimized to maximize extraction efficiency.

• Solvent extraction method Polar solvents such as methanol, ethanol, or water alcohol mixed systems are usually used. Due to the high polarity of the compound, a high proportion of water or low concentration ethanol (such as 50-70% ethanol) often yields better extraction results. The extraction process often uses heating reflux or ultrasound assisted extraction to improve mass transfer efficiency. After concentration, the extract can be preliminarily purified by liquid-liquid extraction (such as extraction with ethyl acetate or n-butanol) to remove lipid soluble impurities.
• Modern extraction techniques In order to further improve efficiency and reduce solvent consumption,Microwave assisted extraction and Pressurized solvent extraction The technology has also been applied to the extraction of flavonoid glycosides. These methods accelerate the dissolution of target components by disrupting the cell wall structure.
• Separation and purification The 6HK-3,6,7-Glc in the crude extract needs to be separated and purified through multi-step chromatographic techniques. Common methods include:
  • Macroporous adsorption resin Models such as D101 and AB-8 enrich flavonoid glycosides through adsorption desorption processes.
  • Polyamide column chromatography The use of hydrogen bonding between polyamide and flavonoids is a classic method for separating flavonoid glycosides.
  • Preparation type high-performance liquid chromatography For the preparation of high-purity samples, especially for the separation of structurally similar compounds, preparative HPLC is the ultimate choice. Usually, a reverse phase C18 column is used, with water acetonitrile or water methanol system as the mobile phase, and separation is achieved through gradient elution.

Pharmacological activity research

The pharmacological activity research of 6-hydroxykaempferol-3,6,7-tri-O-glucoside mainly focuses on its strong antioxidant capacity, which has led to potential intervention effects on various oxidative stress-related diseases.

1. Antioxidant activity

This is the most core and extensively studied pharmacological activity of 6HK-3,6,7-Glc. Its antioxidant mechanism is multifaceted:

• Direct free radical scavenging Multiple phenolic hydroxyl groups in the molecular structure, especially the 4 '- OH in the B ring and the 5-OH and 6-OH in the A ring, are excellent hydrogen atom donors that can directly neutralize reactive oxygen species (ROS) and reactive nitrogen species (RNS), such as hydroxyl radicals (· OH), superoxide anions (O ₂⁻ ·), peroxynitrite (ONOO ⁻), etc. In vitro chemical experiments (such as DPPH, ABTS, FRAP methods) have confirmed that it has significant antioxidant capacity, and its activity is even better than some classic antioxidants such as vitamin C or vitamin E.
• Chelation of metal ions Flavonoids can chelate transition metal ions (such as Fe ² ⁺, Cu ² ⁺), thereby inhibiting the Fenton reaction, reducing the generation of · OH, and blocking the oxidative chain reaction from the source.
• Activate endogenous antioxidant system This is the key to its long-lasting antioxidant effect at the cellular level. Research has shown that 6HK-3,6,7-Glc can upregulate the expression and activity of various antioxidant enzymes, including superoxide dismutase (SOD1, SOD2), catalase (CAT), and glutathione peroxidase (GPX1). These enzymes form the first line of defense for cells against oxidative damage.

2. Skin protection and anti photoaging

The skin is one of the main target organs of oxidative stress, and ultraviolet (UV) radiation is the main exogenous factor leading to skin photoaging and skin cancer. 6HK-3,6,7-Glc shows great potential in skin protection:

• Inhibition of matrix metalloproteinases (MMPs)UV radiation can induce overexpression of MMPs (such as MMP1 and MMP3) in skin fibroblasts, leading to degradation of collagen and elastin, which is the main cause of skin sagging and wrinkle formation. 6HK-3,6,7-Glc can significantly inhibit the expression and activity of UVB induced MMP1 and MMP3, thereby protecting the integrity of the skin extracellular matrix.
• Inhibition of Tyrosinase (TYR)Tyrosinase is a key rate limiting enzyme in melanin synthesis, and abnormal increase in its activity can lead to pigmentation (such as melasma and freckles). Research has found that 6HK-3,6,7-Glc can effectively inhibit the activity of tyrosinase and reduce the production of melanin, demonstrating its potential as a whitening active ingredient.
• Reduce oxidative damage Protect skin keratinocytes and fibroblasts from oxidative stress-induced apoptosis and DNA damage by clearing excess ROS generated by UV radiation.

3. Anti inflammatory activity

Oxidative stress and inflammatory response are closely related and mutually causal. The antioxidant activity of 6HK-3,6,7-Glc also lays the foundation for its anti-inflammatory effect. Research has shown that this compound can inhibit the production of pro-inflammatory cytokines (such as TNF - α, IL-6, IL-1 β) and nitric oxide (NO) in macrophages stimulated by lipopolysaccharide (LPS). The mechanism may be related to the inhibition of the activation of the NF - κ B signaling pathway.

4. Cardiovascular protection

Oxidized low density lipoprotein (ox LDL) is a key factor in the occurrence and development of atherosclerosis. 6HK-3,6,7-Glc can inhibit the oxidative modification of LDL through its antioxidant activity. In addition, it can protect endothelial cells from oxidative stress damage, maintain normal vasodilation function of blood vessels, and may exert antithrombotic effects by inhibiting platelet aggregation.

Mechanism of action and molecular targets

The pharmacological effects of 6-hydroxykaempferol-3,6,7-tri-O-glucoside are not solely dependent on direct chemical reactions, but are achieved through precise regulation of multiple signaling pathways within cells. Its core mechanism mainly revolves around Nuclear factor E2 related factor 2 (NRF2) The signal pathway unfolds.

1. Activation of NRF2/ARE signaling pathway

NRF2 is a core transcription factor that cells use to respond to oxidative stress and electrophilic substances. Under physiological conditions, NRF2 binds to the inhibitory protein KEAP1 in the cytoplasm and is in an inactive state degraded by ubiquitination. When cells are exposed to oxidative stress or electrophilic compounds, the conformation of KEAP1 changes, releasing NRF2. Activated NRF2 translocates into the nucleus and binds to antioxidant response elements (ARE), initiating the transcription of a series of downstream protective genes.

6HK-3,6,7-Glc has been confirmed to be an effective activator of NRF2. Its mechanism of action may include:
- Directly modify KEAP1 The phenolic hydroxyl groups in the compound may be oxidized into quinone structures, which then covalently bind to cysteine residues (such as Cys151, Cys273, Cys288) on the KEAP1 protein, causing conformational changes in KEAP1 and releasing NRF2.
- Activate upstream kinase By activating upstream signaling pathways such as PI3K/Akt and MAPK (such as ERK, JNK, p38), phosphorylating NRF2 or KEAP1 promotes nuclear translocation of NRF2.

By activating NRF2, 6HK-3,6,7-Glc, a series of antioxidant and detoxifying enzymes can be upregulated, which is the key to its long-lasting and broad-spectrum protective effects. These target genes include:
- antioxidant enzyme：SOD1(Copper zinc superoxide dismutase)SOD2(Manganese Superoxide Dismutase)CAT(Catalase)GPX1(Glutathione peroxidase 1)HMOX1(Heme oxygenase 1). The products of HMOX1, biliverdin/bilirubin and carbon monoxide, have antioxidant and anti-inflammatory activities.
- Detoxifying enzyme Glutathione S-transferases (GSTs), quinone oxidoreductase 1 (NQO1), etc.

2. Regulation of MMPs and TYR

• Inhibition of MMP1/MMP3 In addition to indirectly inhibiting the activation of MMPs by clearing ROS, 6HK-3,6,7-Glc may also directly downregulate the gene transcription of MMP1 and MMP3 by inhibiting the activity of MAPK (such as JNK, p38) and AP-1 (activator protein-1) transcription factors. AP-1 is a key transcription factor that regulates the expression of MMPs, and its activity is regulated by the MAPK pathway.
• Inhibit TYR The inhibitory effect of 6HK-3,6,7-Glc on tyrosinase may involve two aspects: firstly, it directly chelates with copper ions in the enzyme's active center, competitively inhibiting its catalytic activity; The second is to reduce the protein level of the enzyme by inhibiting the gene expression of TYR or accelerating its degradation.

3. Summary of key molecular targets

In summary, the main molecular targets of 6HK-3,6,7-Glc can be summarized as follows:
- Upstream signaling molecules：KEAP1、PI3K、Akt、MAPKs（ERK, JNK, p38）。
- Core transcription factors：NRF2（NFE2L2）。
- effector protein：SOD1、SOD2、CAT、GPX1、HMOX1、MMP1、MMP3、TYR。

This multi-target and multi pathway regulatory mode enables 6HK-3,6,7-Glc to synergistically resist oxidative stress from multiple levels and exert comprehensive protective effects.

Evaluation of drug properties and pharmacokinetics

To push 6-hydroxykaempferol-3,6,7-tri-O-glucoside from the laboratory to clinical application, strict evaluation of its pharmacological properties is necessary. Based on its physicochemical properties and preliminary pharmacokinetic predictions, this compound faces significant challenges but also unique opportunities.

1. Pharmaceutical advantages

• High water solubility LogP is -1.8760, with good water solubility (4.9928), which facilitates its dissolution and distribution in aqueous media such as plasma and extracellular fluid, avoiding bioavailability issues caused by poor solubility.
• low toxicity Preliminary predictions indicate that it has no hERG inhibitory activity (low risk of cardiac toxicity) and a negative Ames test (no mutagenicity), suggesting that it has a good safety window.
• Clear target mechanism The multi-target mechanism of action centered on NRF2 is clear and meets the requirements of modern drug development for a clear mechanism of action.

2. Challenges in drug development

• Extremely low membrane permeability This is the biggest obstacle that 6HK-3,6,7-Glc faces in drug development. Its molecular weight (788.66 Da) far exceeds the threshold of molecular weight<500 in Lipinski's Rule of Five, and its TPSA is as high as 368.81 Å ². These characteristics determine that it is difficult to pass through the cell membrane through passive diffusion, resulting in poor oral absorption and extremely low bioavailability.
• Low blood-brain barrier penetration Restricted its application in central nervous system diseases such as Alzheimer's disease and Parkinson's disease.
• Metabolic stability As a polysaccharide, it may be hydrolyzed by gut microbiota or brush edge enzymes in the gastrointestinal tract, gradually removing glycosides and generating secondary glycosides or aglycones. This metabolic process may either reduce the exposure of its prototype drug or convert it into more active metabolites (such as 6-hydroxykaempferol). Therefore, further research is needed to determine whether its pharmacological effects originate from the prototype or metabolites.

3. Pharmacokinetic characteristics (prediction and preliminary study)

• absorb Poor oral absorption and low bioavailability. Limited active transport may occur through glucose transporters in the intestine, such as SGLT1.
• distribution Due to its high water solubility, it is mainly distributed in extracellular fluid and blood. The binding rate with plasma proteins may be low.
• Metabolism Metabolism mainly occurs in the intestine and liver. The metabolic pathways include: deglycosylation (producing 6-hydroxykaempferol-3,6-diglucoside, 6-hydroxykaempferol-3-glucoside or aglycone), methylation, sulfation, and glucuronidation.
• excretion Mainly excreted in the form of metabolites through bile and urine.

4. Strategies for improving drug properties

Given the bottleneck of low oral bioavailability, future drug development strategies should focus on:
- Prodrug design Esterification or etherification modification of hydroxyl groups in molecules to enhance their lipophilicity, allowing them to be passively diffused and absorbed into the body before being converted into active forms by esterases or enzymatic hydrolysis.
- nano-formulation Using nanocarrier technologies such as liposomes, polymer nanoparticles, and solid lipid nanoparticles, the compound is encapsulated to enhance its oral absorption and targeted delivery capabilities.
- Non oral administration route: Develop transdermal drug delivery preparations (such as cream and gel) for skin care and anti light aging; Or develop injections (such as intravenous injection) for the treatment of acute oxidative stress injury.
- Simplified structure Retain the core active groups (such as 6-hydroxykaempferol), reduce the number of sugar groups, and design analogs with simpler structures and better membrane permeability.

Clinical application prospects and prospects

Although 6-hydroxykaempferol-3,6,7-tri-O-glucoside faces challenges in oral drug development, its unique pharmacological activity and good safety make its application prospects in specific fields still broad.

1. Skin care and cosmetics field

This is the closest application direction of 6HK-3,6,7-Glc to industrialization. Its powerful antioxidant, tyrosinase inhibiting, and MMPs inhibiting activities make it an ideal choice Anti aging, whitening, sun protection Active ingredients. By means of transdermal administration (such as adding to face cream, essence liquid and facial mask), the problem of oral absorption can be bypassed and the target cells of skin can be directly acted on. Its high water solubility also makes it easy to formulate in water-based cosmetics. In the future, developing nano lipid carriers or microemulsion formulations containing 6HK-3,6,7-Glc to improve their skin permeability and stability will be a research hotspot.

2. Functional foods and dietary supplements

As a natural ingredient in cruciferous vegetables such as broccoli, 6HK-3,6,7-Glc can be considered as a type of Dietary antioxidants Although its individual oral bioavailability is low, its metabolites (such as 6-hydroxykaempferol) may accumulate in the body and exert systemic antioxidant effects through long-term dietary intake. It has a certain market potential to develop it into functional food raw materials or dietary supplements to help prevent chronic diseases related to oxidative stress (such as cardiovascular diseases, diabetes complications). It should be emphasized that its efficacy needs to be validated through rigorous clinical research.

3. Drug development

For diseases that require systematic administration, such as Acute lung injury, ischemia-reperfusion injury, non-alcoholic fatty liver disease The bioavailability of 6HK-3,6,7-Glc needs to be addressed through pharmaceutical methods. Once efficient oral or injectable formulations are successfully developed, their potential as NRF2 agonists will be fully unleashed. Especially, compared with NRF2 agonists currently under clinical research (such as dimethyl fumarate and otipram), 6HK-3,6,7-Glc, as a natural product, may have better safety.

4. Future research directions

• In depth mechanism research Using gene knockout animal models (such as NRF2-/- mice) and cell models, further confirm the central role of the NRF2 pathway in its in vivo pharmacological effects. Meanwhile, explore whether it also acts on other signaling pathways such as SIRT1 and FOXO.
• Metabolite activity research Systematically study its metabolites in vivo, especially the activity of 6-hydroxykaempferol glycoside, to clarify its true pharmacological substance basis.
• Study on Structure Activity Relationship By synthesizing a series of structurally similar compounds and systematically comparing the effects of sugar group quantity, position, and hydroxyl substitution mode on activity, solubility, and membrane permeability, guidance is provided for structural optimization.
• Clinical translational research Conduct small-scale clinical trials to first validate its safety and effectiveness in the field of skin care. Then, with appropriate formulation technology support, explore its clinical efficacy in specific diseases.

Conclusion

6-Hydroxykaempferol-3,6,7-tri-O-glucoside, as a structurally unique natural flavonol glycoside, has shown great potential in skin protection, anti-aging, and prevention and treatment of oxidative stress-related diseases due to its excellent antioxidant activity, clear NRF2 signaling pathway regulation mechanism, and effective inhibition of tyrosinase and matrix metalloproteinases. Its high water solubility and low toxicity provide a good safety foundation for drug development. However, its extremely low membrane permeability and oral bioavailability are the core challenges facing its drug development. Future research should focus on overcoming this bottleneck through pharmaceutical methods such as nanodelivery systems or prodrug design strategies, while delving deeper into their in vivo metabolic processes and metabolite activity. It can be foreseen that with the deepening of research and technological progress, 6-hydroxykaempferol-3,6,7-tri-O-glucoside is expected to gradually transform from a laboratory research tool into a cosmetic active ingredient, functional food raw material, and even a candidate drug for treating oxidative stress-related diseases with practical application value, contributing to the human health cause.