480-11-5Relevant articles and documents
5,6,7-TRISUBSTITUTED FLAVONES FROM GOMPHRENA MARTIANA
Buschi, C. A.,Pomilio, A. B.,Gros, E. G.
, p. 1178 - 1179 (1981)
Two 5,6,7-trisubstituted flavones have been isolated from Gomphrena martiana and indentified as 5,6-dimethoxy-7-hydroxyflavone and 5,6-dihydroxy-6-methoxyflavone.Key Word Index -Gomphrena martiana; Amaranthaceae; flavonoids; 5,6-dimethoxy-7-hydroxyflavone; 5,7-dihydroxy-6-methoxyflavone.
An unambiguous and practical synthesis of Oroxylin A: a commonly misidentified flavone
Hemantha, Hosahalli P.,Ramanujam, Rajendran,Majeed, Muhammed,Nagabhushanam, Kalyanam
, p. 1413 - 1420 (2019/08/22)
Oroxylin A, a major flavonoid in the extracts of Oroxylum indicum as well as Scutellaria baicalensis possesses useful medicinal properties. Many of the published routes claiming the synthesis of Oroxylin A (1) have in fact led to a regioisomer Negletein that was misinterpreted as Oroxylin A. In the present work, we describe a novel, straight-forward and scalable semi-synthetic approach for rapid access to the title compound, the structure of which is unambiguously secured by NMR and X-ray crystallographic analysis of a derivative. This work also encompasses the synthesis of a glycosylated derivative of Oroxylin A viz OAGME (2), which has marked pharmacological importance.
Crystal structures of the flavonoid Oroxylin A and the regioisomers Negletein and Wogonin
Grano, Ruel Valerio Robles De,Nisar, Madiha,Sung, Herman H.-Y.,Vashchenko, Elena V.,Vashchenko, Valerii V.,Williams, Ian D.
, p. 490 - 499 (2020/05/18)
The flavonoid Oroxylin A (6-methoxychrysin or 5,7-dihydroxy-6-methoxy-2- phenyl-4H-chromen-4-one, C16H12O5) and its regioisomers are of increasing interest for a variety of bioactive functions and their pharmaceutical formulation is of importance. Previous difficulties in the separation and misidentification of Oroxylin A from its regioisomers Wogonin (8-methoxychrysin or 5,7-dihydroxy-8-methoxy-2-phenyl-4H-chromen-4-one) and Negletein (5,6- dihydroxy-7-methoxyflavone or 5,6-dihydroxy-7-methoxy-2-phenyl-4H-chromen- 4-one) render its full structural and powder X-ray characterization highly desirable. The low-temperature (100 K) crystal structures of Oroxylin A, Negletein and Wogonin sesquihydrate are reported for the first time. Wogonin crystallizes in two related but distinct hydrated forms. These have very similar powder diffractograms, indicating that such issues need to be addressed for its pharmaceutical formulation.
Process for Preparing Oroxylin A
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Paragraph 0033-0038, (2019/03/08)
A process for preparing oroxylin A includes: subjecting baicalin to a methylation reaction using a methylating reagent in the presence of a base to methylate the 6-hydroxyl group of baicalin, so as to form a methylated compound; and subjecting the methylated compound to a deglucuronidation reaction in the presence of an acid, so as to form oroxylin A.
