Antioxidant flavonoids from the seed of Oroxylum indicum

Three new flavonoid glycosides (1–3) and nineteen known compounds (4–22) were isolated from the aqueous ethanolic extract of the seed of Oroxylum indicum. The structures of 1–3 were elucidated on the basis of spectroscopic analysis. Antioxidant activities of all the isolated compounds were evaluated using a DPPH and an ORAC assay. Compounds 3, 5–7, 9 and 12 exhibited potent antioxidant activity in the DPPH assay, while compounds 3–15 showed potent antioxidant capacity in the ORAC assay, and seven antioxidant flavonoids (4–6, 8, 9, 11, 12) were detected as the main ingredients in the methanolic extract of seed of O. indicum using an HPLC analysis.

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