SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Xanthone-2-carboxylic acids 4a-4k were synthesized as potential antiphlogistic compounds, and compounds 4a-4c and 4f-4i were tested for anti-inflammatory and analgesic properties. In the carrageenin paw edema the most potent of the series acid 4b displayed the activity which was approx one third of that of ketoprofen.
By appropriate superimposing of fenofibrate and fenofibric acid molecules, two xanthone derivatives (closed models) may be obtained. These compounds as well as their four chlorine-free isomers were prepared and tested on adrenaline- and theophylline-induced lipolysis in rat fat cells in comparison with ethyl 2-(4-chlorophenoxy)-2-methylpropionate (clofibrate). Some of these new derivatives besides being good inhibitors of adrenaline effect, as clofibrate is, were also very active in reducing theophylline-induced lipolysis. Very promising for further studies is the chlorine-free 3-isomer (3e). The possible difference in the action mechanism of these compounds as compared with clofibrate and the structure-activity relationships are briefly discussed.
A series of xanthone 1,4-dihydropyridine derivatives bearing a 2,3-lactone ring and a 2-acetoxymethyl group were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonist properties. The introduction of a 2,3-lactone ring improved the negative inotropic activity and selectivity.
A series of 2-substituted 1,4-dihydropyridines with a xanthone backbone was prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonist properties.
A series of xanthone and fluorenone-1,4-dihydropyridine derivatives bearing a 5-phosphonate group were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonistic properties. The insertion of a phosphonate group is detrimental for inotropic and calcium antagonistic activity but improves the potency and selectivity for chronotropism.
A series of alkanolamides and alkanoamines derivatives of xanthone were prepared and evaluated for antiepileptic activity in the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazol seizure threshold (ScMet) assays and for neurotoxicity (TOX). Several analogues from the appropriate alkanolamines were found to be active in both the anticonvulsant tests. Most interesting were the anticonvulsant results of the appropriate 2-amino- or 2-N-methylamino-1-butanol derivatives of 7-chloroxanthone 8-11, which displayed anti-MES activity with a protective index (TD50/ED50) in the range 2.84-3.62 for 8-11 corresponding with that for phenytoin, carbamazepine and valproate.
Synthesis and physicochemical properties of alkanolamine derivatives of xanthone are described. Alkanolamines were synthesized by of the reaction of an appropriate aminoalcohol with corresponding 2-bromomethylxanthones. The obtained compounds 1-13 were evaluated for anticonvulsant activity in the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole seizure threshold (scMet) assays and for neurotoxicity (TOX). Several alkanolamines were found to be active in both the anticonvulsant tests. Most interesting were the 2-amino-1-propanol-, 1-amino-2-propanol- or 1-amino-2-butanol derivatives of 6-methoxy- or 6-chloroxanthone, which displayed anti MES activity with a protective index (TD50/ED50) in the range 2.21-5.84 corresponding with that for phenytoin, carbamazepine and valproate.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
From the rhizomes of Swertia speciosa, a traditional medicinal plant from the Himalayan region of Uttaranchal (North India), a new constituent, 6-hydroxy-3,5-dimethoxy-1-[(6-O-beta-D-xylopyranosyl-beta-D-glucopyranosyl)oxy]-9H-xanthen-9-one (8), was isolated, together with nine known compounds. Their structures were elucidated on the basis of chemical, physical, and spectroscopic evidence. Both the acetone and MeOH extracts, as well as the known constituents ursolic acid (5) and 1,5,8-trihydroxy-3-methoxy-9H-xanthen-9-one (6) exhibited potent antioxidant activities in different biological assays (Table 2).
Chemical investigations of a microfungus Xylaria sp. isolated from the Australian rainforest tree Glochidion ferdinandi have afforded two new natural products, 2-hydroxy-6-methyl-8-methoxy-9-oxo-9H-xanthene-1-carboxylic acid (1) and 2-hydroxy-6-hydroxymethyl-8-methoxy-9-oxo-9H-xanthene-1-carboxylic acid (2). Compound 1 has previously been synthesised but only partially characterised. Methylation of 1 using diazomethane afforded the crystalline compound 2,8-dimethoxy-6-methyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ester (3), whose structure was determined by single crystal X-ray analysis. This paper reports the full spectroscopic characterisation of compounds 1-3 by NMR, UV, IR and MS data. All compounds were inactive in a brine shrimp lethality assay and several antimicrobial screens.
We recently demonstrated that 2,3,4,5,6-pentahydroxyxanthone (X5) inhibits the in vitro growth of both chloroquine-sensitive and multidrug-resistant strains of P. falciparum. To study the molecular basis of its antimalarial action, we tested X5 and selected hydroxyxanthone analogs as inhibitors of in vitro heme polymerization in a low ionic strength phosphate solution at mildly acidic pH. We found that addition of 1 Eq. of X5 resulted in complete inhibition of polymerization in this system whereas addition of up to 40 Eqs. of standard antimalarial compounds (chloroquine, primaquine, quinacrine, artemisinin and methylene blue) had no such effect although these compounds did co-precipitate with heme. The antimalarial potency of the hydroxyxanthones correlated well with their ability to inhibit in vitro heme polymerization in our assay, suggesting that these compounds exert their antimalarial action by preventing hemozoin formation. Based on the observed structure-activity relationships, we propose a model displaying possible interactions between hydroxyxanthones and heme.
Explore the source record for details and available documents.
8-Carboxymethyl-1,6-dihydroxy-3,5-dimethoxyxanthone, 8-carboxymethyl-1,5,6-trihydroxy-3-methoxyxanthone and 8-carboxymethyl-1,3,5,6-tetrahydroxyxanthone were isolated from the capitula of Leiothrix curvifolia and Leiothrix flavescens and characterized by spectroscopic methods, mainly 1D and 2D NMR experiments, as well as by electrospray mass spectrometry. Eight known flavonoids were also isolated and they were identified by 1D and 2D NMR experiments and comparison with literature data.
The isolation of 1-hydroxy-3,7-dimethoxyxanthone (1) from Shultesia guianensis is reported along with relevant NMR spectra, including new data by two-dimensional NMR experiments (HMQC and HMBC).
The organic extract of the plant Maclura tinctoria exhibited moderate anti-HIV activity. Seven prenylated phenolic derivatives were isolated from the active fractions and characterized by spectroanalytical methods. New compounds macluraxanthone B (1), macluraxanthone C (2), and dihydrocudraflavone B (8) were identified.
The new isoprenylated tetrahydroxyxanthone, 2,3,6,8-tetrahydroxy-1-(3-methylbut-2-enyl)-5-(2-methylbut-3-en-2-yl)-9H-xanthen-9-one (1), was isolated from the root bark of Cudrania tricuspidata together with macluraxanthone B (2) and cudraxanthone L (3), which were fully characterized by NMR spectroscopic and X-ray crystallographic analyses.
Ascherxanthone A (1), a novel symmetrical tetrahydroxanthone dimer, was isolated from the entomopathogenic fungus Aschersonia sp. BCC 8401. The structure of 1 was elucidated by spectroscopic analysis, especially 2D-NMR. Compound 1 exhibited activity against Plasmodium falciparum K1 with an IC(50) value of 0.20 microg/mL, but it also showed cytotoxic activities against Vero cells and three tumor cell lines.