Isolation of flavonoids from Oroxylum indicum (Vent.) stem bark and their antioxidant activity using DPPH assay

Author Details
D. C. Deka⁴, Vimal Kumar^{1, 4,*}, Kamal Kumar³, Chandan Prasad⁵, R. B. Srivastava ^2 
1Science Laboratory, Arcaheological Survey of India, Dehradun,284001, India
²Defence Institute of High Altitude Research, c/o 56 APO ‐ 901205, India
³Defence Materials and Stores Research and Development Establishment, Kanpur- 208013,Uttar Pradesh, India
⁴Department of Chemistry, Gauhati University, Guwahati-781014, Assam, India
⁵Department of Chemistry, D.A.V. College, Kanpur- 208001, Uttar Pradesh, India

Abstract
Four flavonoids were isolated from the ethyl acetate extract of stem bark of Oroxylum indicum (Vent.) and identified as 3,4,5–trihydroxy– 6-(7′-methoxy-4′-oxo-2′-phenyl-5′-hydroxy-3′-H-chromen-6′-yoloxy) tetra hydro- pyran-2-carboxylic acid methyl ester (Compound I, unknown), with three known compounds: Chrysin, Scutellarein, Baicalein. The increasing order of IC₅₀ values reported were Quercetin (standard) < Compound 1 < Trolox (standard) < Baicalein < Scutellarein < Ascorbic acid (standard) < Chrysin in DPPH assay.
Keywords: Oroxylum indicum, Flavonoid, Antioxidant, Ester, DPPH