Showing papers on "Isovitexin published in 2000"

The application of atmospheric pressure chemical ionisation liquid chromatography-mass spectrometry in the chemotaxonomic study of flavonoids: characterisation of flavonoids from Ocimum gratissimum var. gratissimum.

Abstract: Liquid chromatography coupled to mass spectrometry (LC-MS), using atmospheric pressure chemical ionisation (APCI), was found to complement data obtained from diode array detection enabling common flavonoids in Ocimum gratissimum var. gratissimum to be characterised at the analytical level without complete purification, or even to be characterised in crudely purified ethanolic extracts. Xanthomicrol, cirsimaritin, rutin, kaempferol 3-O-rutinoside and vicenin-2 were identified as the major flavonoids, whereas luteolin 5-O-glucoside, luteolin 7-O-glucoside, apigenin 7-O-glucoside, vitexin, isovitexin, quercetin 3-O-glucoside and isothymusin were detected as minor constituents. First-order positive ion APCI-MS provided not only the pseudomolecular ion of flavonoid O-glycosides, but also an ion corresponding to the aglycone and an intermediate ion if more than one sugar was attached to the flavonoid. Information on the type and sequence of sugars was therefore obtained without the need to undertake MS2 product ion analyses. Product ion analysis was useful for confirming the glycoside fragmentation observed in first-order MS, especially with co-eluting compounds, and for obtaining fragmentation patterns of either free aglycones or the aglycone moiety of flavonoid O-glycosides; the latter could be used to support the aglycone identification achieved from the UV spectra. Negative ion APCI-MS was found useful for flavone C-glycosides and gave very characteristic product ions due to fragmentation of the C-sugars. For flavonoid O-glycosides analysed in the negative ion mode, there was evidence that the position and nature of the attached sugars could influence the aglycone product ion formed by MS2 analysis and hence its product ion spectrum. APCI is considered to be a more useful ion source than electrospray in the chemotaxonomic study of flavonoids. Copyright © 2000 John Wiley & Sons, Ltd.

Flavonoid Glycosides from Terminalia catappa L.

Abstract: Under the inhibition of Cu+2-induced LDL oxidation-guided fractionation, two new flavone glycosides with galloyl substitution were isolated from the dried fallen leaves of Terminalia catappa L. Their structures were established as apigenin 6-C-(2″-O-galloyl)-β-D-glucopyranoside (1) and apigenin 8-C-(2″-O-galloyl)-β-D-glucopyranoside (2), together with four known flavone glycosides, isovitexin, vitexin, isoorientin, and rutin, on the basis of spectroscopic method. Compounds 1 and 2 showed significant antioxidative effects. Their IC50 were 2.1 and 4.5 μM, respectively.

Stability of flower colors due to anthocyanin-flavone copigmentation in Japanese garden iris, Iris ensata Thunb.

Abstract: The fading of flower color in bluish purple and reddish purple cultivars of Iris ensata and the in vitro stability of malvidin 3RGac5Gand petunidin 3RGac5G due to copigmentation with isovetixin under different pH conditions were examined. The bluish purple cultivars exhibited higher flower color stability than the reddish purple cultivars 2 days after anthesis. In the absence of isovitexin, malvidin 3RGac5G and petunidin 3RGac5G were not able to maintain color stability except at low pH. However, the color stability of malvidin 3RGac5G and petunidin 3RGac5G was increased by copigmentation with isovitexin under all pH conditions tested. Most remarkable was the stabilization of both anthocyanins due to the copigmentation at pH 4.2–6.2. Therefore, it can be concluded that the stability of flower color in the bluish purple cultivars of malvidin 3RGac5Gand petunidin 3RGac5G type of I. ensata is caused at least in part by the copigmentation between these anthocyanins and isovitexin.

Major Antioxidative Substances in Boreava orientalis (Cruciferae)

Abstract: Antioxidative activities for lipid peroxidation of C-glycosylflavones isolated from the fruits of Boreava orientalis and related compounds were studied. C-glycosylflavones, especially isovitexin and isoorientin, were found to be antioxidative constituents of the fruits of B. orientalis. The activity of isoorientin was stronger than that of isovitexin.