Showing papers on "Isovitexin published in 2003"

Complex C-glycosyl flavonoid phytoalexins from Cucumis sativus.

Abstract: Extraction of cucumber leaf tissue expressing induced resistance against powdery mildew fungi revealed the presence of two new major C-glycosyl flavonoid products: vitexin-6-(4-hydroxy-1-ethylbenzene) (cucumerin A, 1) and isovitexin-8-(4-hydroxy-1-ethylbenzene) (cucumerin B, 2). In addition, the known C-glycosyl flavonoids apigenin-8-C-beta-D-glucopyranoside (vitexin, 3), apigenin-6-C-beta-D-glucopyranoside (isovitexin, 4), luteolin-8-C-beta-D-glucopyranoside (orientin, 5), and luteolin-6-C-beta-D-glucopyranoside (isoorientin, 6), as well as 4-hydroxycinnamic acid (p-coumaric acid, 7) and its methyl ester (p-came, 8), were found in higher quantities within resistant plants. The structures of 1-8 were elucidated using spectroscopic methods and unambiguously confirmed for 3-8 using co-chromatography experiments with authentic standards. On the basis of the results of this study and the reported biological activities of C-glycosyl flavonoids, these compounds would play a vital role in the defense strategy of this species by acting as phytoalexins.

Phenolic constituents and antioxidant properties of Xanthosoma violaceum leaves.

Abstract: An extract of Xanthosoma violaceum leaves was subjected to a polyphenol profile determination, including total polyphenols, and antioxidant activity evaluation. Analysis of the extract resulted in the isolation of a new flavone C-glycoside, apigenin 6-C-β-d-glucopyranosyl-8-C-β-d-apiofuranoside (1), as well as known flavone C-glycosides, including vitexin (2), isovitexin (3), isovitexin 4‘-O-rhamnopyranoside (4), apigenin 6-C-[β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside] (5), and apigenin 6,8-diC-β-d-glucopyranoside (6). The antioxidant activity of the extract was assessed by means of two different in vitro tests: bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test) and peroxidation induced by the water-soluble radical initiator 2,2‘-azobis(2-amidinopropane) hydrochloride, on mixed dipalmitoylphosphatidylcholine/linoleic acid unilamellar vesicles (LP-LUV test). In both tests used, the extract and a fraction II showed a significant antioxidant/free-radical scavenging effect (fraction...

Flavone C-Glycoside, Phenolic Acid, and Nitrogen Contents in Leaves of Barley Subject to Organic Fertilization Treatments

Abstract: From the leaves of barley, Hordeum vulgare, one new flavone C-glucoside and three known flavone glucosides were isolated and characterized by (1)H and (13)C NMR and MALDI-TOF-MS. The novel flavone C-glucoside was isovitexin 7-O-beta-[6' "-O-(E)-p-coumaroyl]glucoside (6' "-coumaroylsaponarin), and the known compounds were isovitexin 7-O-beta-[6' "-O-(E)-feruloyl]glucoside, isoorientin 7-O-beta-[6' "-O-(E)-feruloyl]glucoside, and tricin 7-O-beta-glucoside. The sum of all the flavone glycosides and soluble phenolic acids in the leaves decreased with increased rate of plant nutrients given in animal manure and with increased crop yield. All of the major phenylpropanoids showed the same general response to nutrient level. The concentration of nitrogen in the leaves was not directly related to nutrient application or to contents of phenylpropanoids.

Antioxidative, antihyaluronidase and antityrosinase activities of some constituents from the aerial part of Piper elongatum Vahl.

Abstract: Seven known compounds, pyrroside B (1), swertisin (2), isovitexin (3), isoswertiajaponin (4), vomifoliol (blumenol A) (5), (6S,9R)-roseoside (6) and angelicoidenol (7) were isolated from the methanol (MeOH) extract of the aerial part of Piper elongatum VAHL. and their structures were identified on the basis of physical and spectral data. In addition, the antioxidative activity of 1–4 was evaluated by the ferric thiocyanate method. All these compounds showed stronger antioxidative activity than that of α-tocopherol. Furthermore, the scavenging effects on 1,1-diphenyl-2-picrylhydrazyl (DPPH), the antihyaluronidase and the antityrosinase activities of 1–4, asebogenin (8), 2′,6′-dihydroxy-4′-methoxydihydrochalcone (9), 3-geranyl-4-methoxybenzoic acid (10), 3-geranyl-4-hydroxybenzoic acid (11), nervogenic acid (12) and 2,2-dimethyl-6-carboxyl-8-prenyl-chromene (13), which were previously isolated from the MeOH extract were evaluated. Compounds 4, 8 and 9 showed higher radical scavenging effect than that of L-cysteine, and 4, 8 and 11 exhibited stronger inhibition effect on the activation of hyaluronidase than that of tranilast. Compound 8 indicated almost the same antityrosinase activity as that of kojic acid.

High-speed countercurrent chromatography as a valuable tool to isolate C-glycosylflavones from Cecropia lyratiloba Miquel.

Abstract: A new apigeninglycoside, apigenin 6-C-galactosyl-6″-O-β-galactopyranoside (1), isoorientin, and a mixture of orientin and isovitexin were isolated from leaves of Cecropia lyratiloba by high-speed countercurrent chromatography using a solvent system containing ethyl acetate, butanol, methanol and water. The structural elucidation of 1 was based on NMR spectroscopy. Copyright © 2003 John Wiley & Sons, Ltd.

Pharmaceutical compositions for lowering blood glucose and blood cholesterol levels

Abstract: Methods of treating a mammal with high blood-glucose, or high blood-cholesterol, levels with isovitexin, and pharmaceutical compositions comprising the same are disclosed.

GONOCYTISUS PTEROCIADUS BiTKiSiNiN FLAVONOİTLERİ

Abstract: Ten flavonoids were isolated from the aerial parts of Gonocytisus pterocladus and identified using thin-layer chromatography, melting points and spectroscopic methods (UV and H NMR) as apigenin, chrysoeriol, luteolin, luteolin 7 O-glucoside, luteolin 7 O-rutinoside, vitexin, isovitexin, rhamnosyl vitexin, orientin and isoorientin.