Following references reporting isolation of isovitexin and its derivatives may be consulted:-

Frank R. Stermitz, Elliott W. Mead, Tommaso A. Foderaro, Castro C. Oscar (1993). Diphysin, a 3-3″-dimeric 4-phenyldihydrocoumarin from Dyphysa robinioides. Phytochemistry, 34 (1): 287–289

Fatma A. Moharrama and Mohamed S. A. Marzoukb (2007). A Novel Phenylethanoid Dimer and Flavonoids from Jacaranda mimosaefolia. Z. Naturforsch. 62b: 1213 – 1220.

Chulia Albert J. Vercauteren, Joseph, Mariotte, Anne Marie (1998). Iridoids and flavones from Gertiana depressa. Phytochemistry, 42(1): 139-143.

Hilsenbeck, R.A.; Mabry, T.J. (1990). Flavonoid chemistry of Siphonoglossa. Phytochemistry, 29(7): 2181-2185.

Wilson, A. (1985). Flavonoid pigments of butterflies in the genus Melanargia. Phytochemistry , 24(8):1685-1691

Goetz, M.; Hostettmann, K.; Jacot-Guillarmod, A. (1976). A new C-glycosylflavone from Gentiana asclepiadea. Phytochemistry, 15 (12): 2014.

Mai NT, Coung NX, Thao, NP, Nam, NH, Khoi NH, Minh, CV, Heyden, YV, Thuan, NT, Tuyen, NV, Quetin-Leclercq, J., Kiem, PV (2010). A new lignan dimer from Mallotus philippensis. Nat. Prod. Commun. 5(3): 423-426.

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Thanks Dr. Tripathi, I will follow the information.