hispidulin and kaempferol

Up to now, the metabolism of hispidulin (5,7,4'-trihydroxy-6-methoxyflavone), a potent ligand of the central human benzodiazepine receptor, has not been investigated. To elucidate the metabolism of hispidulin in the large intestine, its biotransformation by the pig caecal microflora was studied. In addition, the efficiency of the pig caecal microflora to degrade galangin (3,5,7-trihydroxyflavone), kaempferol (3,5,7,4'-tetrahydroxyflavone), apigenin (5,7,4'-trihydroxyflavone), and luteolin (5,7,3',4'-tetrahydroxyflavone) was investigated. Identification of the formed metabolites was performed by high-performance liquid chromatography (HPLC)-diode array detection, HPLC-electrospray ionization-tandem mass spectrometry, and high-resolution gas chromatography-mass spectrometry. The caecal microflora transformed hispidulin to scutellarein (5,6,7,4'-tetrahydroxyflavone), an effective alpha-glucosidase inhibitor, and 3-(4-hydroxyphenyl)-propionic acid; galangin to phenylacetic acid and phloroglucinol; kaempferol to 4-hydroxyphenylacetic acid, phloroglucinol, and 4-methylphenol; apigenin to 3-(4-hydroxyphenyl)-propionic acid and 3-phenylpropionic acid, and luteolin to 3-(3-hydroxyphenyl)-propionic acid, respectively. To elucidate to what extent different hydroxylation patterns on the B-ring influence the degradation degree of flavonoids, the conversions of galangin and kaempferol as well as that of apigenin and luteolin were compared with those of quercetin (3,5,7,3',4'-pentahydroxyflavone) and chrysin (5,7-dihydroxyflavone), respectively. Regardless of the flavonoid subclass, the presence of a hydroxy group at the 4'-position seems to be a prerequisite for fast breakdown. An additional hydroxy group at the B-ring did not affect the degradation degree.

Topics: Animals; Apigenin; Bacteria; Cecum; Chromatography, High Pressure Liquid; Flavones; Flavonoids; Gas Chromatography-Mass Spectrometry; Humans; Kaempferols; Kinetics; Luteolin; Models, Animal; Quercetin; Spectrometry, Mass, Electrospray Ionization; Swine

A number of natural and synthetic flavonoids have been assessed previously with regard to their effects on the activity of cyclin-dependent kinases (Cdk1 and -2) related to the inhibition of cell cycle progression. On the other hand, the Cdk5/p35 system is of major importance in neuronal migration phenomena and brain development, and its deregulation is implicated in neurodegenerative diseases, particularly Alzheimer's. Here we show that some natural flavonoids inhibit the activity of the Cdk5/p35 system in the micromolar range, while others are practically inactive. Ring B-unsubstituted and highly methoxylated flavones were inactive or gave irreproducible results, and 6-methoxyapigenin and 6-methoxyluteolin were the most potent Cdk5 complex inhibitors within this series, while the common flavonols kaempferol and quercetin showed intermediate behavior. The reported crystal structure of the Cdk5 complex with its activator p25 was used for docking studies, which also led to the identification of the two 6-methoxyflavones, kaempferol and quercetin, as well as the untested 6-methoxy derivatives of kaempferol and quercetin and the corresponding 6-hydroxy analogues as compounds exhibiting a good fit to the active site of the enzyme.

Topics: Algorithms; Centaurea; Cyclin-Dependent Kinase 5; Cyclin-Dependent Kinases; Flavonoids; Flavonols; Inhibitory Concentration 50; Kaempferols; Molecular Conformation; Molecular Structure; Quercetin; Structure-Activity Relationship

To study the chemical constituents the roots of Chirita fimbrisepala.. The constituents were extracted with solvent, separated and purified with chromatographic methods, identified by NMR, MS, UV, IR and physical-chemical constants.. Three flavonoids mahuangchiside(I), hispidulin (II) and kaempferol(III) were isolated with daucosteral(IV).. I is a new compound elucidated as hispidulin-7-O-beta-D-xylopyranosyl-(1-->2)-beta-D-xylopyranoside, named mahuangchiside, II and III were isolated for the first time from the family Gesneriaceae, and IV was isolated for the first time from the genus Chirita.

Topics: Disaccharides; Flavones; Flavonoids; Isoflavones; Kaempferols; Magnoliopsida; Molecular Structure; Plant Roots; Plants, Medicinal; Sitosterols