isoflavan

Isoflavan is a class of flavonoid compounds within the larger isoflavonoid family. It refers to the dihydro derivatives of isoflavones, in which the C-ring of the flavonoid skeleton is saturated at the 2-3 bond, giving a 2,3-dihydro-1-benzopyran framework with a phenyl substituent at the appropriate position. Isoflavans occur in various plant species, particularly legumes, though they are less widely distributed than their isoflavone precursors. They are typically found in trace to moderate amounts in seeds, roots, and leaves and may be produced biosynthetically from isoflavones through enzymatic reduction.

Biological activity of isoflans has been investigated in the context of flavonoids. They may exhibit antioxidant properties, and some compounds within this class can show phytoestrogenic activity or interactions with estrogen receptors, although activities are highly compound-specific. Isoflavans can serve as intermediates in plant biosynthetic pathways, including the formation of more complex isoflavonoids such as pterocarpans, a class of phytoalexins, via cyclization reactions.

Because of structural similarity to other flavonoids, isoflans are often grouped with isoflavones and other isoflavonoids in phytochemical and pharmacological literature, but they are chemically distinct by saturation of the heterocyclic ring. Research on isoflans focuses on plant chemistry, biosynthesis, and potential health-related effects of individual compounds, rather than a single representative activity for the class.