title: Nobiletin: a citrus flavonoid displaying potent physiological activity.
abstract: Nobiletin [systematic name: 2-(3,4-dimethoxyphenyl)-5,6,7,8-tetramethoxy-4H-chromen-4-one; C21H22O8] is a flavonoid found in citrus peels, and has been reported to show a wide range of physiological properties, including anti-inflammatory, anticancer and antidementia activities. We have solved the crystal structure of nobiletin, which revealed that the chromene and arene rings of its flavone moiety, as well as the two methoxy groups bound to its arene ring, were coplanar. In contrast, the C atoms of the four methoxy groups bound to the chromene ring are out of the plane, making the molecule conformationally chiral. A comparison of the crystal structures of nobiletin revealed that it could adopt a variety of different conformations through rotation of the covalent bond between the chromene and arene rings, and the orientations of methoxy groups bound to the chromene ring.
authors: Graduate Division of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-Ku, Shizuoka, Japan.
authors: Shuji
authors: S
authors: Noguchi
authors: Graduate Division of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-Ku, Shizuoka, Japan.
authors: Haruka
authors: H
authors: Atsumi
authors: Graduate Division of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-Ku, Shizuoka, Japan.
authors: Yasunori
authors: Y
authors: Iwao
authors: Graduate Division of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-Ku, Shizuoka, Japan.
authors: Toshiyuki
authors: T
authors: Kan
authors: Graduate Division of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-Ku, Shizuoka, Japan.
authors: Shigeru
authors: S
authors: Itai
mesh_terms: D002957:Citrus / Q000737:chemistry*; D018360:Crystallography, X-Ray; D047309:Flavones / Q000737:chemistry* / Q000494:pharmacology*; D005419:Flavonoids / Q000737:chemistry* / Q000494:pharmacology*; D006860:Hydrogen Bonding; D015394:Molecular Structure
chemical_list: D047309:Flavones; D005419:Flavonoids; C008661:nobiletin
keywords: O-methylated flavonoid; conformational chirality; crystal packing; crystal structure; enantiomers; nobiletin; powder diffraction; synchrotron study