Topic
Xanthone
About: Xanthone is a research topic. Over the lifetime, 1639 publications have been published within this topic receiving 25870 citations. The topic is also known as: 9-oxo-xanthene & Diphenyline ketone oxide.
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TL;DR: In this paper, the chemical structures of two xanthone compounds contributing to the coloration of red-flowered gentian petals were determined by mass spectrometry and nuclear magnetic resonance spectroscopy.
Abstract: Cultivated Japanese gentians traditionally produce vivid blue flowers because of the accumulation of delphinidin-based polyacylated anthocyanins. However, recent breeding programs developed several red-flowered cultivars, but the underlying mechanism for this red coloration was unknown. Thus, we characterized the pigments responsible for the red coloration in these cultivars. An HPLC-PDA analysis revealed the presence of phenolic compounds, including flavones and xanthones, as well as the accumulation of colored cyanidin-based anthocyanins. The chemical structures of two xanthone compounds contributing to the coloration of red-flowered gentian petals were determined by mass spectrometry and nuclear magnetic resonance spectroscopy. The compounds were identified as norathyriol 6-O-glucoside (i.e., tripteroside designated as Xt1) and a previously unreported norathyriol-6-O-(6'-O-malonyl)-glucoside (designated Xt2). The copigmentation effects of these compounds on cyanidin 3-O-glucoside were detected in vitro. Additionally, an RNA-seq analysis was performed to identify the cDNAs encoding the enzymes involved in the biosynthesis of these xanthones. Recombinant proteins encoded by the candidate genes were produced in a wheat germ cell-free protein expression system and assayed. We determined that a UDP-glucose-dependent glucosyltransferase (StrGT9) catalyzes the transfer of a glucose moiety to norathyriol, a xanthone aglycone, to produce Xt1, which is converted to Xt2 by a malonyltransferase (StrAT2). An analysis of the progeny lines suggested that the accumulation of Xt2 contributes to the vivid red coloration of gentian flowers. Our data indicate that StrGT9 and StrAT2 help mediate xanthone biosynthesis and contribute to the coloration of red-flowered gentians via copigmentation effects.
7 citations
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TL;DR: In this paper, two xanthones and two caged-prenylated Xanthones, named cochinchinones A-D and a synthetically known CPGXXanthone, together with seven known compounds were isolated from the roots of Cratoxylum cochichinense (Lour.) Blume.
Abstract: Two xanthones and two caged-prenylated xanthones, named cochinchinones A-D, respectively, and a synthetically known caged-prenylated xanthone, together with seven known compounds were isolated from the roots of Cratoxylum cochinchinense (Lour.) Blume. Their structures were assigned on the basis of analyses of spectroscopic data. Some of the compounds exhibited effective antioxidative properties.
7 citations
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TL;DR: Results of 13C and 2H n.r.m. analyses of [2H33]- and [1,2-13C22]-acetate-enriched tajixanthone are reported, which indicate that ring cleavage of an anthraquinone, and not anthrone, precursor must precede C-prenylation, and that dihydropyran ring formation precedes xanthone ring formation during biosynthesis of tajxanthone.
Abstract: The results of 13C and 2H n.m.r. analyses of [2H33]- and [1,2-13C22]-acetate-enriched tajixanthone are reported, which indicate, inter alia, that ring cleavage of an anthraquinone, and not anthrone, precursor must precede C-prenylation, and that dihydropyran ring formation precedes xanthone ring formation during biosynthesis of tajixanthone.
7 citations
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TL;DR: A series of 15 ω-aminoalkoxylxanthones containing methyl, ethyl, propyl, tert-butylamino and piperidinyl moieties synthesized from a natural xanthone isolated from a lichen species revealed selective activity against Staphylococcus aureus and inhibited tumor cells growth.
Abstract: A series of 15 ω-aminoalkoxylxanthones containing methyl, ethyl, propyl, tert-butylamino and piperidinyl moieties were synthesized from a natural xanthone isolated from a lichen species. These compounds were tested for their in vitro antibacterial properties against Gram-positive and Gram-negative bacteria and cytotoxicity against a number of human tumor cell lines was too evaluated. The newly synthesized derivatives revealed selective activity against Staphylococcus aureus (Gram-positive), and the most promising results are for a multidrug resistant strain, for which six of these compounds showed good activity (MICs 4 µg/mL). Many derivatives inhibited tumor cells growth and most compounds were active on multiple lines.
7 citations
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TL;DR: In this paper, the petrol and methanol extracts of the bark and timber of Garcinia thwaitesii have been investigated and β-amyrin and tirucallol, four biflavonoids and a new xanthone, 2,5-dihydroxy-1,6-dimethoxyxanthone have been isolated and characterized.
7 citations