4'-Hydroxy-3-methoxyflavones with potent antipicornavirus activity

Area of Science:

• Natural Product Chemistry
• Virology
• Medicinal Chemistry

Background:

• 4'-Hydroxy-3-methoxyflavones are natural compounds with established antiviral properties against picornaviruses.
• Picornaviruses, including poliovirus and rhinoviruses, cause significant human diseases.
• Understanding structure-activity relationships is crucial for developing effective antiviral agents.

Purpose of the Study:

• To synthesize and evaluate novel 4'-hydroxy-3-methoxyflavone analogues for antiviral activity.
• To establish structure-activity relationships for this class of compounds.
• To compare the antiviral efficacy and cytotoxicity of synthetic analogues with naturally occurring flavones.

Main Methods:

• Synthesis of a series of 4'-hydroxy-3-methoxyflavone analogues.
• In vitro antiviral assays against poliovirus and various rhinovirus serotypes.
• Cytotoxicity assessments and mutagenicity testing (Ames test).

Main Results:

• Specific structural features, including the 4'-hydroxyl group, 3-methoxyl group, 5-position substitution, and a polysubstituted A ring, were identified as essential for high antiviral activity.
• 4',7-dihydroxy-3-methoxy-5,6-dimethylflavone demonstrated exceptional in vitro efficacy, with TI99 values >1000 for poliovirus type 1 and >200 for rhinovirus type 15.
• This lead compound exhibited broad-spectrum activity against multiple rhinovirus serotypes (MIC50 values from 0.016 to 0.5 µg/mL) and was found to be non-mutagenic in the Ames test, unlike quercetin.

Conclusions:

• The synthetic analogue 4',7-dihydroxy-3-methoxy-5,6-dimethylflavone represents a promising lead compound for antiviral drug development against picornaviruses.
• The study successfully elucidated key structural requirements for potent antiviral activity within this flavone class.
• The non-mutagenic profile of the lead compound suggests a favorable safety profile for further investigation.