Product name: 6-Demethoxytangeretin
Synonym name: 4',5,7,8-Tetramethoxyflavone; 6-Demethoxytangeritin; Tetra-O-methylisoscutellarein
Catalogue No.: BP1787
Cas No.: 6601-66-7
Formula: C₁₉H₁₈O₆
Mol Weight: 342.347
Botanical Source: Citrus sinensis
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.
We provide solution to improve the water-solubility of compounds, thereby facilitating the variety of activity tests and clinic uses.

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

Description:

6-Demethoxytangeretin has anti-inflammatory activity, it also can suppress production and gene expression of interleukin-6 in human mast cell-1 via anaplastic lymphoma kinase and mitogen-activated protein kinase pathways. 6-Demethoxytangeretin can suppress the interleukin 1 (IL-1) induced production of proMMP-9/progelatinase B in rabbit synovial cells in a dose dependent manner (<64 microM).

References:

Biol Pharm Bull. 2013;36(10):1646-9.    

6-demethoxynobiletin, a nobiletin-analog citrus flavonoid, enhances extracellular signal-regulated kinase phosphorylation in PC12D cells.    

We previously demonstrated that nobiletin, a polymethoxylated flavone isolated from citrus peels, has the potential to improve cognitive dysfunction in patients with Alzheimer's disease (AD). Recent studies suggest that the generation of intraneuronal amyloid-beta (Aβ) oligomers is an early event in the pathogenesis of AD. Aβ oligomers cause deficits in the regulation of the extracellular signal-regulated kinase (ERK) signaling which is critical for consolidation of the memory. Our previous studies revealed that nobiletin activated ERK signaling and subsequent cyclic AMP response element-dependent transcription. 

METHODS AND RESULTS:

In this study, the effects of five nobiletin analogs, 6-demethoxynobiletin, tangeretin, 5-demethylnobiletin, sinensetin, and 6-Demethoxytangeretin, isolated from citrus peels were assessed on ERK phosphorylation in PC12D cells, and the structure-activity relationships were examined. PC12D cells were treated with nobiletin or its analogs, and the cell extracts were analyzed by Western blotting using an antibody specific to phosphorylated ERK. 6-Demethoxynobiletin markedly enhanced ERK phosphorylation in a concentration-dependent manner. 

CONCLUSIONS:

These results may be useful in developing drugs and functional foods using citrus peels for the treatment of dementia including AD.    

J Rheumatol. 2000 Jan;27(1):20-5.    

A citrus flavonoid, nobiletin, suppresses production and gene expression of matrix metalloproteinase 9/gelatinase B in rabbit synovial fibroblasts.    

Flavonoids including nobiletin are known to exert many biological actions in vitro. We investigated the chondroprotective effect of citrus flavonoids, especially nobiletin, using cultured rabbit synovial fibroblasts and articular chondrocytes. 

METHODS AND RESULTS:

We examined the effects of citrus flavonoids on the production and gene expression of matrix metalloproteinases (MMP) and prostaglandin E2 (PGE2)production in rabbit synovial fibroblasts. Six flavonoids isolated from Citrus depressa Rutaceae including tangeretin, 6-Demethoxytangeretin, nobiletin, 5-demethylnobiletin, 6-demethoxynobiletin, and sinensetin suppressed the interleukin 1 (IL-1) induced production of proMMP-9/progelatinase B in rabbit synovial cells in a dose dependent manner (<64 microM); nobiletin most effectively suppressed proMMP-9 production along with the decrease in its mRNA. Nobiletin also reduced IL-1 induced production of PGE2 in the synovial cells, but did not modify the synthesis of total protein. These suppressive effects of nobiletin were also observed in rabbit articular chondrocytes. Nobiletin inhibited proliferation of rabbit synovial fibroblasts in the growth phase. 

CONCLUSIONS:

These results suggest nobiletin is a novel antiinflammatory candidate that has the potential to inhibit PGE2 production, matrix degradation of the articular cartilage, and pannus formation in osteoarthritis and rheumatoid arthritis. CONCLUSION: These results suggest nobiletin is a novel antiinflammatory candidate that has the potential to inhibit PGE2 production, matrix degradation of the articular cartilage, and pannus formation in osteoarthritis and rheumatoid arthritis.    

HPLC of 6-Demethoxytangeretin

NMRof 6-Demethoxytangeretin

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

Introduction/Overview

Flavonoids, as one of the most widely distributed plant secondary metabolites in nature, have always been an important source of drug development and functional food development due to their diverse chemical structures and extensive biological activities. Citrus fruits are not only important global economic crops, but also a treasure trove of methoxyflavonoids. 6-Demethoxytangeretin (6-DMT), CAS number 6601-66-7, is a structurally unique and highly active member. As a derivative of Tangeretin, 6-DMT exhibits different physicochemical properties and biological activity spectra due to the lack of a methoxy group in its molecule.

In recent years, with the deepening of research on chronic inflammatory diseases, metabolic syndrome, and neurodegenerative diseases, the multi-target regulatory advantages of natural products have become increasingly prominent. The research on 6-DMT has expanded from early anti-inflammatory and anti allergic activities to explore its potential anti-cancer activities, neuroprotection, and alcoholic liver disease. Its mechanism of action involves precise regulation of key signaling pathways (such as NF - κ B, MAPK, Nrf2, etc.) and specific molecular targets (such as TLR4, AKR1B1, etc.), demonstrating great potential as lead compounds or dietary supplements. This article aims to systematically review the chemical properties, plant sources, pharmacological activities, mechanisms of action, medicinal properties, and clinical application prospects of 6-DMT, in order to provide comprehensive scientific references for the in-depth research and development of this compound.

Chemical structure and physicochemical properties

6-Methoxyhesperidin belongs to the class of multi methoxyflavones, and its chemical name is 5-hydroxy-4 ', 6,7,8-tetramethoxyflavone. Compared with the parent compound hesperidin (5,6,7,8,4 '- pentamethoxyflavone), 6-DMT lacks a methoxy group (- OCH ∝) at the C-6 position and is replaced by a hydroxyl group (- OH). This structural difference is the material basis for its unique biological activity.

Its molecular formula is C ₁₉ H ₁₈ O ₇, and its molecular weight is 342.3470. Based on the analysis of the pharmacological parameters, the lipid water partition coefficient (LogP) of the compound is 2.8418, indicating that it has moderate lipophilicity and is conducive to transmembrane transport and absorption. The topologically polar surface area (TPSA) is 67.13 Å ², which is relatively low due to the presence of multiple methoxy substituents and fewer polar groups in the molecule. However, its water solubility is poor, only 0.0052 mg/mL, which to some extent limits its bioavailability and is a key issue that needs to be overcome in formulation development. It is worth noting that the prediction shows that it has high blood-brain barrier permeability, which provides the possibility for it to exert central nervous system related pharmacological effects (such as promoting CRE mediated transcription in hippocampal neurons). In the preliminary safety screening, its hERG inhibitory activity was negative, indicating a low risk of cardiac toxicity; The Ames test result is 0.6 (usually considered positive if>1.5), indicating a low risk of mutagenicity, but further in vitro and in vivo experiments are needed to confirm.

Plant sources and extraction methods

6-DMT mainly exists in the peel, leaves, and flowers of citrus plants in the Rutaceae family, and is one of the contributors to the characteristic flavor and biological activity of citrus fruits. Common sources include sweet oranges, wide skinned oranges, lemons, grapefruits, etc., especially in the white sponge layer (white skin layer) and oil cell layer of citrus peels where the content is relatively high. Its content is influenced by factors such as citrus variety, origin, maturity, and storage conditions.

The extraction of 6-DMT from plant materials typically follows the general extraction strategy for flavonoids. Traditional methods include organic solvent reflux extraction or cold soaking, with commonly used solvents including methanol, ethanol, acetone, and their mixed solutions with water. Due to the fact that 6-DMT belongs to the class of multi methoxy flavonoids with relatively low polarity, high proportion organic solvents (such as 80-95% ethanol) have better extraction efficiency. Modern extraction techniques such as ultrasound assisted extraction, microwave-assisted extraction, and supercritical CO ₂ extraction have been widely used, which can significantly shorten extraction time, improve yield, and reduce solvent consumption.

The crude extract after extraction needs further separation and purification to obtain high-purity 6-DMT. The conventional separation steps include: liquid-liquid distribution using different polar solvents such as petroleum ether and ethyl acetate to preliminarily enrich the target components; Subsequently, silica gel column chromatography, polyamide column chromatography or dextran gel column chromatography were used for separation; The final high-purity preparation relies on high-performance liquid chromatography, especially preparative HPLC. Structural identification involves the comprehensive use of techniques such as ultraviolet spectroscopy, infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy.

Pharmacological activity research

Numerous in vitro and in vivo pharmacological studies have shown that 6-DMT has multiple biological activities, with its core revolving around anti-inflammatory, antioxidant, and cell protective effects.

1. Anti inflammatory and anti allergic activity This is one of the earliest reported activities of 6-DMT. Research has confirmed that it can effectively inhibit the production of pro-inflammatory factors such as interleukin-6 (IL-6) in human mast cells and downregulate the expression of related genes. This inhibitory effect is closely related to the regulation of ALK and MAPK signaling pathways. In various inflammatory cell models, 6-DMT exhibits inhibitory ability on the release of inflammatory mediators.
2. Protective effect of alcoholic liver disease This is currently a hot area of research in 6-DMT. The pathological process of alcoholic liver disease involves oxidative stress, inflammatory response, lipid metabolism disorder, and hepatocyte apoptosis. Research has shown that 6-DMT can intervene in this process through multiple targets: reducing oxidative damage, inhibiting liver inflammation, and regulating lipid metabolism related genes (such as SREBF1), thereby significantly improving alcohol induced liver injury, steatosis, and fibrosis in animal models.
3. Neuroprotection and cognitive enhancement activity The high blood-brain barrier permeability of 6-DMT enables it to function in the central nervous system. Research has shown that it can promote cAMP response element binding protein mediated transcription in hippocampal neurons. CREB is a key transcription factor in the process of learning and memory, and its activation is closely related to neural plasticity and neuronal survival. This suggests that 6-DMT has potential value in improving cognitive function and combating neurodegenerative diseases.
4. Antioxidant and Nrf2 pathway activation 6-DMT can induce gene expression driven by antioxidant response elements, such as quinone oxidoreductase 1 (NQO1). This effect is usually achieved by activating the core regulatory factor of the cellular defense system, nuclear factor E2 related factor 2 (NFE2L2/Nrf2). Activation of the Nrf2 pathway helps cells resist oxidative stress and electrophilic attacks, and is one of the common mechanisms underlying its hepatoprotective and neuroprotective effects.
5. Other potential activities Preliminary studies also suggest that 6-DMT may have the potential to inhibit proliferation and induce tumor cell apoptosis, but its anti-cancer activity and specific mechanism still need to be further explored. In addition, its improvement effect on metabolic diseases (such as diabetes) is also beginning to show signs, which may be related to the regulation of PPARG and other targets.

Mechanism of action and molecular targets

The pharmacological effects of 6-DMT are not achieved through a single target, but exhibit typical natural product multi-target and multi pathway synergistic effects. The network of action for diseases such as alcoholic liver disease is relatively clear:

1. Inhibition of TLR4/NF - κ B inflammatory axis Toll like receptor 4 (TLR4) is a key receptor that recognizes endogenous danger signals (such as alcohol metabolites) and initiates inflammatory responses. 6-DMT can inhibit the activation of TLR4, thereby blocking the activation of its downstream nuclear factor kappa B (NFKB1/NF - κ B) signaling pathway. The inhibition of NF - κ B leads to a decrease in the expression of key pro-inflammatory factors and mediators such as tumor necrosis factor - α (TNF - α), interleukin-1 β (IL-1 β), and cyclooxygenase-2 (PTGS2/COX-2), thereby alleviating liver inflammation damage from the source.
2. Activate Nrf2/ARE antioxidant pathway As mentioned earlier, 6-DMT is an effective activator of Nrf2. It may modify the cysteine residues on Keap1 protein to dissociate and translocate Nrf2 to the nucleus, bind to antioxidant response elements (ARE), initiate transcription of a series of phase II detoxifying enzymes and antioxidant proteins such as NQO1, heme oxygenase-1 (HO-1), glutathione S-transferase (GST), etc., enhance the antioxidant defense ability of liver cells, and combat oxidative stress caused by alcohol.
3. Regulating lipid metabolism related targets Alcoholic liver disease is accompanied by severe hepatic steatosis. 6-DMT can affect sterol regulatory element binding protein 1 (SREBF1/SREBP-1c), which is a major transcription factor controlling fatty acid synthesis. Inhibition of SREBP-1c activity can reduce de novo synthesis of liver fat. Meanwhile, it may also regulate the uptake, storage, and oxidation of fatty acids through targets such as peroxisome proliferator activated receptor gamma (PPARG), thereby improving liver lipid accumulation.
4. Inhibition of aldose reductase (AKR1B1)Aldose reductase is a key enzyme in the polyol pathway, which is closely related to the complications of diabetes and oxidative stress. The latest research shows that AKR1B1 is also abnormally activated in alcoholic liver disease, catalyzing the production of toxic aldehydes. The inhibitory effect of 6-DMT on AKR1B1 helps to reduce the accumulation of toxic aldehyde products and alleviate their damage to the liver.
5. Regulating MAPK and other signaling pathways The mitogen activated protein kinase (MAPK) family (such as ERK, JNK, p38) is involved in regulating cell proliferation, differentiation, stress, and apoptosis. 6-DMT can regulate the MAPK pathway, affecting the production of inflammatory factors and cell fate determination, complementing its anti-inflammatory and cell protective effects.

Evaluation of drug properties and pharmacokinetics

Although 6-DMT has shown good pharmacological activity, its pharmacological development still faces challenges, and pharmacokinetic studies are relatively limited.

1. Absorption, distribution, metabolism, excretion (ADME)：

   • absorb Its moderate LogP value indicates good intestinal permeability, but extremely low water solubility may be the main limiting step for its oral absorption. The key to improving absorption is to use techniques such as nano formulations, solid dispersions, or cyclodextrin inclusion to enhance its solubility.
   • distribution The predicted high blood-brain barrier permeability has been indirectly supported by some pharmacological experiments, indicating its distribution to the central nervous system. Its distribution characteristics in other tissues, such as the liver, need further research.
   • Metabolism As a flavonoid compound, 6-DMT is likely to undergo extensive phase I and phase II metabolism in vivo. Phase I metabolism may involve liver cytochrome P450 enzyme systems (such as CYP1A, CYP3A) mediated demethylation, hydroxylation, etc; Phase II metabolism mainly involves glucuronidation and sulfation. Its metabolites may still have activity or toxicity and require clear identification.
   • excretion Metabolites are mainly excreted through urine and bile.

2. Challenges and optimization strategies for drug development：

   • Poor water solubility This is the most prominent issue. In addition to the above-mentioned formulation strategies, designing prodrugs (such as esterifying phenolic hydroxyl groups) is also a potential direction to improve their bioavailability.
   • structural stability It is necessary to investigate its chemical stability under light exposure and different pH conditions.
   • safety The preliminary hERG and Ames test results are optimistic, but a systematic preclinical safety evaluation is necessary, including acute toxicity, subchronic toxicity, reproductive toxicity, etc.
   • Pharmacokinetic properties Key parameters such as oral bioavailability, half-life, and clearance rate need to be comprehensively determined through animal experiments to provide a basis for dose design.

Clinical application prospects and prospects

Based on its multi-target and multi effect pharmacological properties, 6-DMT has broad development prospects in multiple disease fields:

1. Prevention and treatment of alcoholic liver disease As a natural product with multiple effects of antioxidant, anti-inflammatory, and regulating lipid metabolism, 6-DMT is expected to be developed as a drug or functional food ingredient for the prevention or adjuvant treatment of alcoholic liver disease. Its multi-target mode of action may have more advantages than single target drugs.
2. Neurodegenerative diseases and cognitive impairment It promotes CREB transcriptional activity and high BBB permeability, making it highly promising for the prevention and treatment of diseases such as Alzheimer's disease and vascular dementia. It can be explored for use alone or in combination with existing drugs to improve cognitive function and delay disease progression.
3. Chronic inflammatory diseases Such as allergic asthma, atopic dermatitis, arthritis, etc. Its original anti-inflammatory and anti allergic activities have laid the foundation for its application in this field.
4. Metabolic syndrome: Through the regulation of PPARG, SREBF1 and other targets, the potential benefits of PPARG on lipid metabolism and glucose metabolism deserve further exploration, which may be applicable to the auxiliary management of nonalcoholic fatty liver disease and type 2 diabetes.
5. Development form：
   • drug development As a lead compound, optimize its pharmacological properties through structural modification and develop innovative drugs.
   • Functional foods/dietary supplements Directly in the form of citrus extract or standardized extract enriched with 6-DMT, used for daily health care of sub healthy populations.
   • Drug sensitizer or combination therapy By utilizing its ability to regulate signaling pathways (such as Nrf2) and combining it with existing drugs, it can enhance therapeutic efficacy or reduce side effects.

Future research should focus on: 1) conducting systematic preclinical pharmacological and safety evaluations; 2) Thoroughly elucidate its precise metabolic pathways and main active metabolites in vivo; 3) Using modern technologies such as crystallography and computer simulations to accurately analyze the interaction patterns between it and key targets such as AKR1B1 and TLR4 complexes; 4) Explore advanced drug delivery systems to overcome their solubility bottlenecks.

Conclusion

6-Methoxyhesperidin, as a multi methoxy flavonoid derived from citrus, has become a highlight molecule in the pharmacological research of natural products due to its unique chemical structure and rich biological activity. From anti-inflammatory and anti allergic effects to protective effects against multiple systemic diseases such as alcoholic liver disease, its pharmacological value is constantly being explored. Its mechanism of action clearly outlines a multi-target regulatory network, involving core signaling pathways such as TLR4/NF - κ B, Nrf2/ARE, MAPK, as well as regulation of key targets such as AKR1B1 and SREBF1. Despite facing challenges such as poor water solubility in drug development, these obstacles are expected to be overcome through the optimization of modern medicinal chemistry and formulation methods. With the continuous deepening of research, 6-DMT is expected to move from the laboratory to clinical applications, providing a new natural source of choice for the prevention and treatment of chronic inflammatory, metabolic, and neurodegenerative diseases. At the same time, it will also enhance the added value of citrus by-products and achieve efficient utilization of resources.