Common Flavonoid Carbon Skeleton Structure. Three rings labeled A, B, and C are arranged in a fixed pattern. One vertex in the central ring labeled C is occupied by an oxygen atom rather than carbon. Each vertex is given a label, running from 1 through 8 for the adjacent rings A and C, while ranging from 1′ through 6′ on the offset ring B.
Article of the Year Award: Outstanding research contributions of 2020, as selected by our Chief Editors. Read the winning articles.