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Four new xanthones, caledonixanthones A-D (1-4), were isolated from the trunk bark of Calophyllum caledonicum, in addition to 17 known compounds. The structures of 1-4 were determined by means of spectroscopic analysis and chemical derivatization.
A novel antifungal agent, Sch 54445, was isolated from the fermentation broth of an Actinoplanes species. Sch 54445 was identified as a polycyclic xanthone related to the albofungin family of compounds on the basis of analyses of spectroscopic data. As a broad-spectrum antifungal agent, Sch 54445 exhibits highly potent activities against various yeasts and dermatophytes with MIC values approximately 0.00038 microgram/mL.
A new xanthone derivative, artoindonesianin C (1), was isolated from Artocarpus teysmanii, together with two known prenylated flavonoids, cycloartobiloxanthone and artonin J. The structure of artoindonesianin C (1) was determined on the basis of MS and NMR evidence and by comparison with known related compounds.
PURPOSE: Synthesize and evaluate the protective activity against tertbutylhydroperoxide-induced toxicity in freshly isolated rat hepatocytes of trans-kielcorin, trans-isokielcorin B, as well as their respective building blocks 3,4-dihydroxy-2-methoxyxanthone and 2,3-dihydroxy-4-methoxyxanthone. METHODS: Wistar rats, weighing 200-250g were used. Hepatocyte isolation was performed by collagenase perfusion. Incubations were performed at 37 degrees C, using 1 million cells per milliliter in modified Krebs--Henseleit buffer. The protective activity was evaluated by measuring reduced and oxidized glutathione, lipid peroxidation and cell viability after inducing toxicity with tert-butylhydroperoxide (1.0 mM, 30 min), with or without the studied compounds in the concentrations of 0.025, 0.050, 0.100 and 0.200 mM. Silybin was tested in the same experimental conditions to serve as a positive control. RESULTS: Using these concentrations, the tested compounds prevented tert-butylhydroperoxide-induced lipid peroxidation and cell death in freshly isolated rat hepatocytes. All compounds were also effective in preventing perturbation of cell glutathione homeostasis in some extent. 3,4-Dihydroxy-2-methoxyxanthone and 2,3-dihydroxy-4-methoxyxanthone were more effective than trans-kielcorin and trans-isokielcorin B respectively. Silybin was less effective in protecting cells against lipid peroxidation and loss of cell viability than the four xanthonic derivatives. CONCLUSIONS: The tested compounds protected the freshly isolated rat hepatocytes against tert-butylhydroperoxide-induced toxicity.
Two new xanthones, caledonixanthone M 1 and caloxanthone L 2, and one new acid, caledonic acid 6 were isolated from the hexane-soluble extract of the stem bark of Calophyllum caledonicum. In the course of this phytochemical study, seven other known compounds - calothwaitesixanthone, calozeyloxanthone, allanxanthone, isoapetalic acid 3, calolongic acid 4, apetalic acid 5 and isocalolongic acid 7 - were isolated. Their antifungal activity against the growth of the human pathogenic fungus Aspergillus fumigatus was then investigated. The results indicated that the crude extract, calolongic acid 4 and isocalolongic acid 7 exhibited strong inhibitory effects with MIC (80) values of 8, 4, 2 microg/mL, respectively. Besides, calolongic acid 4, its lactone derivative 4a and isocalolongic acid 7 markedly reduced the respiration of pea seed mitochondria.
The inhibitory effects of 22 xanthones from three Guttiferae plants (Hypericum patulum, Calophyllum inophyllum and C. austroindium) on exogenous platelet activating factor (PAF)-induced hypotension were examined using a blood pressure monitoring in vivo assay method. Guanandin (2), caloxanthone E (3), 1,3,5,6-tetrahydroxy-2-isoprenylxanthone (8), 6-deoxyjacareubin (11) and patulone (18) showed strong inhibition of PAF-induced hypotension, with inhibitory effects of more than 60 %. Their ID50 values were greater than that of ginkgolide B (BN-52 021), a natural PAF-antagonist from the Ginkgo biloba.
A chemical and biological screening of 25 species of the Gentianaceae family has been undertaken. Both methanolic and dichloromethane extracts of Swertia calycina exhibited a strong antifungal activity against Cladosporium cucumerinum and Candida albicans. The compound responsible for this activity has been isolated and identified as 2-methoxy-1,4-naphthoquinone. It is the first naphthoquinone to be described in Gentianaceae species. LC-UV and LC-TSP-MS analysis of the crude extracts of Swertia calycina also allowed on-line identification of six known xanthones and secoiridoids.
Four new isoprenylated xanthones, cudraxanthones L, M, N, and O were isolated from the ethanol extract of the root bark of CUDRANIA TRICUSPIDATA (Carr.) Bur. (Moraceae), collected in China. The structures of cudraxanthones L, M, N, and O were shown to be 1-4, respectively, on the basis of chemical and spectral evidences.
Four new isoprenylated xanthones, cudraxanthone H,I,J, and K were isolated from the ethanol extract of the root bark of CUDRANIA TRICUSPIDATA (Carr.) Bur. (Moraceae), collected in China. The structures of cudraxanthones H,I,J, and K were shown to be 1- 4, respectively, on the basis of chemical and spectral evidence.
Eighteen synthetic xanthone derivatives were tested for their inhibitory effects on the activation of mast cells and neutrophils. 1,3- and 3,5-Dihydroxyxanthone showed strong inhibitory effects on the release of beta-glucuronidase and histamine from rat peritoneal mast cells stimulated with compound 48/80. 1,6-Dihydroxyxanthone and 1,3,8-trihydroxyxanthone showed strong inhibitory effects on the release of beta-glucuronidase, and beta-glucuronidase and lysozyme, respectively, from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP). 1,3- and 1,6-Dihydroxyxanthone, 1,3,7-trihydroxyxanthone, and 1,3,5,6-, 2,3,6,7-, and 3,4,5,6-tetrahydroxyxanthone showed potent inhibitory effects on superoxide formation of rat neutrophils stimulated with fMLP. 1,6- and 3,5-Dihydroxyxanthone showed remarkable inhibitory effects on hind-paw oedema induced by polymyxin B in normal as well as in adrenalectomized mice. These data indicated that the anti-inflammatory effect of these compounds is mediated through the suppression of chemical mediators released from mast cell and neutrophil degranulation.
Six patients with allergic asthma were studied in bronchial challenge tests with their specific antigen. In five cases 7ioxo-7-thiomethoxyxanthone-2-carboxylic acid, sodium salt (OTMX), a new xanthone with mediator-release inhibitory properties, given as an inhaled solution under 'single-blind' conditions, protected against the immediate-type bronchospastic response. This protection was statistically significant (p = 0.016) at the highest dose level used. Late reactions which occurred in two patients were unaffected by the compound.
Two new cytotoxic polycyclic xanthones, actinoplanones A (1) and B (2) were isolated from the culture broth of Actinoplanes sp. R-304 by monitoring their bioactivity against HeLa cells. Compound 1 was extremely cytotoxic (IC50 0.00004 micrograms/ml) against HeLa cells. The structures of 1 and 2 were established mainly by analyses of 2D heteronuclear correlation NMR experiments. The absolute configurations of the asymmetric carbons of the compounds have been assigned to be 9R, 24S, 25R and 27S by circular dichroism spectra and NMR analysis using chiral derivatives (esters of alpha-methoxy-alpha-(trifluoromethyl)acetic acid).
A series of aminoalkanolic derivatives of xanthone were examined in some experimental models of epilepsia, i.e., pilocarpine, aminophylline and pentetrazole-induced seizures. A final objective of this research was to examine the action of these compounds on the central nervous system, namely on spontaneous locomotor activity, amphetamine-induced hyperactivity and narcotic sleep induced by hexobarbital, as well as their influence on the gamma-aminobutyric acid (GABA) level and glutamic acid decarboxylase (GAD) activity in mice brain. The most interesting were the pharmacological results of (R)-2-N-methylamino-1-butanol derivative of 7-chloro-2-methylxanthone [Id], which displayed protective activity against the seizures induced by maximum electroshock and pentetrazole induced seizures; moreover, this compound had a relatively low toxicity and did not exhibit a neurotoxic effect. The influence on the locomotor activity as well as on the amphetamine-induced locomotor hyperactivity in mice was also seen for Id. Compound Id did not decrease the GABA level in mice brain.
The effects of twelve aminoalkanolic derivatives of xanthone on platelet aggregation have been evaluated. Five from them inhibited thrombin-induced platelet aggregation. The most active compound was R-(+)-2-N-(7-chloro-2-xanthonemethyl)-2-N-methylamino-1-butanol [IV] which, at a concentration of 40 micrograms/ml, nearly completely inhibited the aggregation concentration (TAC) of thrombin.
A series of appropriate aminoisopropanoloxy derivatives of 2-, 3- or 6-xanthone was synthesized and evaluated for anticonvulsant activity in the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole seizure threshold (ScMet) assays and for neurotoxicity (TOX). The most interesting result was the anticonvulsant activity of (+/-)-3-(2-propylamino)-1- [(2-methyl)-6-xanthonoxy]-2-propanol hydrochloride (10), which displayed anti-MES activity with a protective index (TD50/ED50) of 0.80. Some of the obtained compounds were also tested for their effect on the circulatory system (influence on the non-working heart perfusion, protection against adrenaline induced-arrhythmia) and acute toxicity.
As continuation of search for antiarrhythmic agents we obtained some alkanolamide derivatives of xanthone-2-acetic acid (I-III).
A series of xanthone 1,4-dihydropyridine derivatives were prepared. The compounds were evaluated for inotropic, chronotropic, and calcium antagonist properties.
A series of xanthone 1,4-dihydropyridine derivatives were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonistic properties. The tested compounds are weak calcium antagonists but exert potent selective bradycardic effects.