hydroxyflavone

Hydroxyflavone is a term used for flavones bearing one hydroxy substituent on the flavone skeleton. In practice, it often refers to monohydroxyflavones such as 3-hydroxyflavone and 4'-hydroxyflavone, though other positional isomers exist. The core structure is the flavone framework: a 2-phenylchromen-4-one system.

Natural occurrence: Hydroxyflavones occur as secondary plant metabolites in many species, frequently as glycosides or within more complex polyphenol mixtures. They contribute to color and defense in plants and are studied as model compounds in flavonoid chemistry.

Synthesis: In the laboratory, hydroxyflavones are prepared through standard flavone synthetic routes, including cyclization of appropriately substituted hydroxychalcones followed by oxidation, or by selective hydroxylation and functional-group manipulation of the flavone nucleus. The position of the hydroxy group strongly influences chemical properties and reactivity.

Properties and applications: Hydroxyflavones typically have limited water solubility and exhibit ultraviolet absorption due to the conjugated ring system; several isomers are fluorescent and are used as probes in chemistry and biochemistry. They can chelate metal ions through the carbonyl and phenolic oxygen atoms and serve as ligands in coordination chemistry. In addition, hydroxyflavones are studied as scaffolds in medicinal chemistry for antioxidant and anti-inflammatory activities.

Safety: Hydroxyflavones are generally handled as laboratory chemicals with standard precautions. Some flavone derivatives can be irritants; consult safety data sheets.