5,7-Dimethoxyflavone
[CAS 21392-57-4]

Identification

• Classification: Biochemical >> Plant extracts
• Name: 5,7-Dimethoxyflavone
• Synonyms: 5,7-Dimethoxy-2-phenyl-4H-chromen-4-one; 5,7-Dimethoxy-4-oxo-2-phenyl-4H-1-benzopyran; Chrysin dimethyl ether
• Molecular Formula: C₁₇H₁₄O₄
• Molecular Weight: 282.29
• CAS Registry Number: 21392-57-4
• EC Number: 979-686-7
• SMILES: COC1=CC2=C(C(=C1)OC)C(=O)C=C(O2)C3=CC=CC=C3

Properties

• Solubility: Insoluble (8.8E^-3 g/L) (25 °C), Calc.^*
• Density: 1.242±0.06 g/cm³ (20 °C 760 Torr), Calc.^*
• Melting point: 201.7 °C^**
• Boiling point: 476.6$+/-$45.0 $degree$C 760 mmHg (Calc.)^*
• Flash point: 213.4$+/-$28.8 $degree$C (Calc.)^*
• Index of refraction: 1.598 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (©1994-2013 ACD/Labs)

^** Sutthanut, K.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319
• Safety Statements: P264-P264+P265-P280-P302+P352-P305+P351+P338-P321-P332+P317-P337+P317-P362+P364

Discovery and Applications

5,7-Dimethoxyflavone is a naturally occurring and synthetically accessible flavone derivative belonging to the flavonoid class of polyphenolic compounds. It possesses the characteristic flavone backbone consisting of two aromatic rings linked through a heterocyclic pyrone ring system. In this compound, methoxy groups are attached at the 5- and 7-positions of the A-ring, giving rise to a dimethoxylated flavone structure.

The molecular framework of 5,7-dimethoxyflavone is based on the flavone nucleus, also known as 2-phenyl-4H-1-benzopyran-4-one. This structure contains a conjugated aromatic system extending across the benzopyranone core and the attached phenyl ring. The extensive π-conjugation contributes to the compound’s ultraviolet absorption properties and chemical stability.

The methoxy substituents (–OCH₃) at the 5- and 7-positions significantly influence the electronic and physicochemical properties of the molecule. Methoxy groups are electron-donating substituents that increase electron density in the aromatic system through resonance effects. Compared with hydroxylated flavones, methoxylation generally increases lipophilicity and metabolic stability.

5,7-Dimethoxyflavone occurs naturally in certain plant species and has been identified among the secondary metabolites of medicinal and aromatic plants. Flavones and related flavonoids are biosynthesized in plants through the phenylpropanoid pathway, where chalcone intermediates undergo cyclization and oxidative transformations to generate the flavone skeleton. Subsequent methylation of hydroxyl groups by O-methyltransferase enzymes produces methoxylated derivatives such as 5,7-dimethoxyflavone.

The compound has been studied extensively in natural products chemistry and pharmacological research because flavones are associated with a broad range of biological activities. Investigations have examined the interactions of 5,7-dimethoxyflavone with enzymes, signaling pathways, inflammatory mediators, and oxidative processes. These studies are part of broader research into flavonoid chemistry and bioactivity relationships.

Chemically, the molecule exhibits the reactivity typical of aromatic methoxy-substituted flavones. The conjugated ketone group within the pyrone ring can participate in nucleophilic and electrophilic reactions under appropriate conditions, while the aromatic methoxy groups can undergo demethylation or substitution reactions. The planar aromatic structure also promotes π–π stacking interactions in the solid state and in molecular recognition processes.

Synthetic preparation of 5,7-dimethoxyflavone commonly involves cyclization of appropriately substituted chalcone intermediates. Classical flavone synthesis methods such as the Baker–Venkataraman rearrangement or oxidative cyclodehydration reactions are frequently employed. Methylation of corresponding hydroxyflavones using methylating agents is another common route.

From a physicochemical perspective, 5,7-dimethoxyflavone is relatively hydrophobic compared with polyhydroxylated flavonoids because the hydroxyl groups are replaced by methoxy substituents. This reduced polarity influences solubility, membrane permeability, and chromatographic behavior. The conjugated aromatic system also contributes to characteristic UV-visible absorption spectra typical of flavones.

Historically, flavones such as 5,7-dimethoxyflavone have played an important role in phytochemistry and natural product research. Structural studies of methoxylated flavones have helped establish relationships between substitution patterns and chemical or biological properties within the broader flavonoid family.

Overall, 5,7-dimethoxyflavone is a methoxylated flavone derivative characterized by a conjugated benzopyranone core and methoxy substituents at the 5- and 7-positions. Its structure, biosynthetic origin, and physicochemical properties make it a representative member of the flavonoid class widely studied in natural products and medicinal chemistry.

References

2026. Self-emulsifying Drug Delivery Systems as a Paradigm for Enhancing Bioavailability of Phytoconstituents. Journal of Solution Chemistry.
DOI: 10.1007/s10953-026-01564-6

2025. 5,7-dimethoxyflavone inhibits hepatocellular carcinoma progression via increasing intestinal Akkermansia muciniphila and hepatic CD8+ T cell infiltration. Chinese Medicine.
URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12505807

2025. Elucidating the Neuroprotective Mechanism of 5,7-Dimethoxyflavone and 5,7’,4’-Trimethoxyflavone Through In Silico Target Prediction and in Memory-Impaired Mice. Neurochemical Research.
URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12370873