Showing papers on "Xanthone published in 2011"

Antibacterial activity of xanthones from guttiferaeous plants against methicillin-resistant Staphylococcus aureus

Abstract: Extracts of Garcinia mangostana (Guttiferae) showing inhibitory effects against the growth of S. aureus NIHJ 209p were fractionated according to guidance obtained from bioassay and some of the components with activity against methicillin-resistant Staphylococcus aureus (MRSA) were characterized. One active isolate, alpha-mangostin, a xanthone derivative, had a minimum inhibitory concentration (MIC) of 1.57-12.5 micrograms mL-1. Other related xanthones were also examined to determine their anti-MRSA activity. Rubraxanthone, which was isolated from Garcinia dioica and has a structure similar to that of alpha-mangostin, had the highest activity against staphylococcal strains (MIC = 0.31-1.25 micrograms mL-1), an activity which was greater than that of the antibiotic vancomycin (3.13-6.25 micrograms mL-1). The inhibitory effect against strains of MRSA of two of the compounds when used in conjunction with other antibiotics was also studied. The anti-MRSA activity of alpha-mangostin was clearly increased by the presence of vancomycin; this behaviour was not observed for rubraxanthone. The strong in-vitro antibacterial activity of xanthone derivatives against both methicillin-resistant and methicillin-sensitive Staphylococcus aureus suggests the compounds might find wide pharmaceutical use.

Genome-Based Deletion Analysis Reveals the Prenyl Xanthone Biosynthesis Pathway in Aspergillus nidulans

Abstract: Xanthones are a class of molecules that bind to a number of drug targets and possess a myriad of biological properties. An understanding of xanthone biosynthesis at the genetic level should facilitate engineering of second-generation molecules and increasing production of first-generation compounds. The filamentous fungus Aspergillus nidulans has been found to produce two prenylated xanthones, shamixanthone and emericellin, and we report the discovery of two more, variecoxanthone A and epishamixanthone. Using targeted deletions that we created, we determined that a cluster of 10 genes including a polyketide synthase gene, mdpG, is required for prenyl xanthone biosynthesis. mdpG was shown to be required for the synthesis of the anthraquinone emodin, monodictyphenone, and related compounds, and our data indicate that emodin and monodictyphenone are precursors of prenyl xanthones. Isolation of intermediate compounds from the deletion strains provided valuable clues as to the biosynthetic pathway, but no genes accounting for the prenylations were located within the cluster. To find the genes responsible for prenylation, we identified and deleted seven putative prenyltransferases in the A. nidulans genome. We found that two prenyltransferase genes, distant from the cluster, were necessary for prenyl xanthone synthesis. These genes belong to the fungal indole prenyltransferase family that had previously been shown to be responsible for the prenylation of amino acid derivatives. In addition, another prenyl xanthone biosynthesis gene is proximal to one of the prenyltransferase genes. Our data, in aggregate, allow us to propose a complete biosynthetic pathway for the A. nidulans xanthones.

Anticancer Activities of Six Selected Natural Compounds of Some Cameroonian Medicinal Plants

Abstract: Background Natural products are well recognized as sources of drugs in several human ailments. In the present work, we carried out a preliminary screening of six natural compounds, xanthone V1 (1); 2-acetylfuro-1,4-naphthoquinone (2); physcion (3); bisvismiaquinone (4); vismiaquinone (5); 1,8-dihydroxy-3-geranyloxy-6-methylanthraquinone (6) against MiaPaCa-2 pancreatic and CCRF-CEM leukemia cells and their multidrug-resistant subline, CEM/ADR5000. Compounds 1 and 2 were then tested in several other cancer cells and their possible mode of action were investigated. Methodology/Findings The tested compounds were previously isolated from the Cameroonian medicinal plants Vismia laurentii (1, 3, 4, 5 and 6) and Newbouldia laevis (2). The preliminary cytotoxicity results allowed the selection of xanthone V1 and 2-acetylfuro-1,4-naphthoquinone, which were then tested on a panel of cancer cell lines. The study was also extended to the analysis of cell cycle distribution, apoptosis induction, caspase 3/7 activation and the anti-angiogenic properties of xanthone V1 and 2-acetylfuro-1,4-naphthoquinone. IC50 values around or below 4 µg/ml were obtained on 64.29% and 78.57% of the tested cancer cell lines for xanthone V1 and 2-acetylfuro-1,4-naphthoquinone, respectively. The most sensitive cell lines (IC50<1 µg/ml) were breast MCF-7 (to xanthone V1), cervix HeLa and Caski (to xanthone V1 and 2-acetylfuro-1,4-naphthoquinone), leukemia PF-382 and melanoma colo-38 (to 2-acetylfuro-1,4-naphthoquinone). The two compounds showed respectively, 65.8% and 59.6% inhibition of the growth of blood capillaries on the chorioallantoic membrane of quail eggs in the anti-angiogenic assay. Upon treatment with two fold IC50 and after 72 h, the two compounds induced cell cycle arrest in S-phase, and also significant apoptosis in CCRF-CEM leukemia cells. Caspase 3/7 was activated by xanthone V1. Conclusions/Significance The overall results of the present study provided evidence for the cytotoxicity of compounds xanthone V1 and 2-acetylfuro-1,4-naphthoquinone, and bring supportive data for future investigations that will lead to their use in cancer therapy.

Xanthone derivatives as potential anti-cancer drugs

Abstract: Xanthone derivatives have been shown to be potent inhibitors of tumour growth. Oxygenated xanthones and [3-(dialkylamino)-2-hydroxypropoxy]xanthones have been prepared and tested for in-vitro inhibition of human PLC/PRF/5, KB and 212 cells. Structure-activity analysis indicated epoxidation of the hydroxyxanthone increased cytotoxicity against tumour cells but ring-opening of the epoxide group with dialkylamine did not enhance the anti-tumour activity. Further evaluation of three of the most active compounds 2, 6-, 3, 6-, and 3, 5-di(2,3-epoxypropoxy)xanthone (compounds 10a, 11a, and 12a, respectively) in DNA, RNA and protein synthesis of tumour cells showed potent inhibitory activity. The 3,5-di(2,3-epoxypropoxy)xanthone also showed potent inhibitory activity against 212 cells, a Ha-ras oncogene-transformed NIH 3T3 cell line. The results indicated that compounds 10a and 12a are potent anti-tumour agents which not only suppressed cellular DNA, RNA and protein synthesis but also specifically inhibited the Ha-ras oncogene in 212 cells.

Cytotoxic and NF-κB inhibitory constituents of the stems of Cratoxylum cochinchinense and their semisynthetic analogues.

Abstract: A new caged xanthone (1), a new prenylxanthone (2), seven known xanthones, and a known sterol glucoside were isolated from the stems of Cratoxylum cochinchinense, collected in Vietnam. Compounds 1 and 2 were determined structurally by analysis of their spectroscopic data. In addition, five new (10 and 16−19) and eight known prenylated xanthone derivatives were synthesized from the known compounds α-mangostin (3) and cochinchinone A (6). Several of these substances were found to be cytotoxic toward HT-29 human colon cancer cells, with the most potent being 3,6-di-O-acetyl-α-mangostin (8, ED50, 1.0 μM), which was tested further in an in vivo hollow fiber assay, but found to be inactive at the highest dose used (20 mg/kg; ip). Of the substances evaluated in a NF-κB p65 inhibition assay, 1,3,7-trihydroxy-2,4-diisoprenylxanthone (5) exhibited the most potent activity (IC50, 2.9 μM). In a mitochondrial transmembrane potential assay, two new compounds, 1 (IC50, 3.3 μM) and 10 (IC50, 1.4 μM), and two known compou...

γ-Pyrone compounds as potential anti-cancer drugs

Abstract: The gamma-pyrones, artomunoxanthotrione epoxide, cyclocommunol, cyclomulberrin, and cyclocommunin exhibited potent inhibition of human PLC/PRF/5 and KB cells in-vitro. Dihydroisocycloartomunin showed significant and potent inhibition of human PLC/PRF/5 and KB cells in-vitro, respectively. Cyclomorusin, dihydrocycloartomunin and artomunoxanthone showed significant inhibition of KB cells in-vitro. Based on the above finding and the reported antileukaemic activity of xanthone psorospermin, a series of natural gamma-pyrones was prepared and the inhibition of human PLC/PRF/5 and KB cells in-vitro was measured. Structure-activity analysis indicated the epoxide group substituted at 3-hydroxyl and 2,6-; 3,6-; and 3,5-dihydroxyl xanthone enhanced the anti-tumour activity. The epoxide group substituted at the 6-hydroxyl group of 1,6-dihydroxyxanthone did not show anti-tumour activity.

A new xanthone derivative from the co-culture broth of two marine fungi (strain No. E33 and K38)

Abstract: A new xanthone derivative, 8-hydroxy-3-methyl-9-oxo-9H-xanthene-1-carboxylic acid methyl ether (1), was isolated from the co-culture broth of two mangrove fungi (strain No. K38 and E33) isolated from the South China Sea coast. The structure of 1 was determined by comprehensive spectroscopic methods, especially 2D NMR techniques. Primary bioassays showed that compound 1 has inhibitory activity against five microorganisms, including Gloeasporium musae and Peronophthora cichoralearum etc.

Root cultures of Hypericum perforatum subsp. angustifolium elicited with chitosan and production of xanthone-rich extracts with antifungal activity

Abstract: Hypericum perforatum is a well-known medicinal plant which contains a wide variety of metabolites, including xanthones, which have a wide range of biological properties, including antifungal activity. In the present study, we evaluated the capability of roots regenerated from calli of H. perforatum subsp. angustifolium to produce xanthones. Root biomass was positively correlated with the indole-3-butyric acid concentration, whereas a concentration of 1 mg l−1 was the most suitable for the development of roots. High auxin concentrations also inhibited xanthone accumulation. Xanthones were produced in large amounts, with a very stable trend throughout the culture period. When the roots were treated with chitosan, the xanthone content dramatically increased, peaking after 7 days. Chitosan also induced a release of these metabolites into the culture. The maximum accumulation (14.26 ± 0.62 mg g−1 dry weight [DW]) and release (2.64 ± 0.13 mg g−1 DW) of xanthones were recorded 7 days after treatment. The most represented xanthones were isolated, purified, and spectroscopically characterized. Antifungal activity of the total root extracts was tested against a broad panel of human fungal pathogen strains (30 Candida species, 12 Cryptococcus neoformans, and 16 dermatophytes); this activity significantly increased when using chitosan. Extracts obtained after 7 days of chitosan treatment showed high antifungal activity (mean minimum inhibitory concentration of 83.4, 39.1, and 114 μg ml−1 against Candida spp., C. neoformans, and dermatophytes, respectively). Our results suggest that root cultures can be considered as a potential tool for large-scale production of extracts with stable quantities of xanthones.

Synthesis and antithrombotic effect of xanthone derivatives.

Abstract: A series of xanthone derivatives was synthesized and tested in-vitro for their ability to inhibit aggregation of rabbit washed platelets and human platelet-rich plasma (PRP) induced by various inducers. 2-Prenyloxyxanthone showed the most potent inhibition of rabbit washed platelet aggregation induced by arachidonic acid (IC50 = 10.2 μM). Of the compounds tested in human PRP, 2-[3 (propylamino)-2-hydroxypropoxy]xanthone (4) hydrochloride salt exhibited the most potent inhibition of platelet aggregation induced by adrenaline (IC50 = 4.4 μM), whereas in evaluation of mouse antithrombotic activity, compound 4 exhibited the most potent protection of mice from thrombotic challenge. Compound 4, 2-[3-(isopropylamino)-2-hydroxypropoxylxanthone hydrochloride salt and 2,5 dihydroxyxanthone suppressed the secondary aggregation induced by adrenaline in human PRP. We conclude that the antiplatelet effects of these compounds are mainly due to an inhibitory effect on thromboxane formation.

Chemical constituents isolated from the bark of Guatteria blepharophylla (Annonaceae) and their antiproliferative and antimicrobial activities

Abstract: Phytochemical study of the bark of Guatteria blepharophylla (Mart.) Mart. afforded twelve compounds, namely two sesquiterpenes, caryophyllene oxide (1) and spathulenol (3), one xanthone, lichexanthone (2), a mixture of steroids, β-sitosterol (4), and stigmasterol (5), and seven isoquinoline alkaloids, O-methylmoschatoline (6), lysicamine (7), nornuciferine (8), liriodenine (9), isocoreximine (10), subsessiline (11), and isomoschatoline (12). Their structures were established on the basis of spectroscopic methods. Compounds 1-6, 11 and 12 were reported for the first time in this species. The 13C NMR (nuclear magnetic resonance) data for the compounds 11 and 12 are described for the first time in the literature. The antiproliferative activity against human tumour cell lines and antimicrobial activities were investigated for the major compounds. Compound 9 showed significant activity against cell lines of breast (MCF-7, Michigan Cancer Foundation-7), superior to the positive control doxorubicin. Compound 12 presented antifungal activity similar to the positive control nystatin against Candida albicans.

Xanthone natural products via N-heterocyclic carbene catalysis: total synthesis of atroviridin.

Abstract: The total synthesis of atroviridin has been accomplished by a linear route involving the N-heterocyclic carbene (NHC)-catalyzed aroylation of the fluorobenzene derivative, Claisen cyclization of the O-propargylated benzophenones, and intramolecular 1,4-addition of the quinone intermediates. The result provides a viable route to xanthone natural products.

Reaction of Benzyne with Formamides and Acetylimidazole

Abstract: The reaction of DMF with o-trimethylsilylphenyl triflate in the presence of CsF afforded dimethyldiphenylammonium triflate, xanthene, and xanthone in 62%, 16%, and 24% yields, respectively. On the ...

Investigation of Anti-inflammatory Properties of Swertia chirayta and Gloriosa superba

Abstract: Gloriosa superba (Liliaceae) is one of the oldest ingredients of species from ancient time. Tubers roots and seeds are two most important part of glory lily used for variety of purpose. Swertia chirata (Gentianaceae) is widely used in India to treat fever and malaria. It is also used to treat liver diseases . The whole plant methanol and aqueous extracts of Swertia chirayta possessed maximum anti-inflammatory activity in a dose dependent manner i.e 50 mg/kg and 100 mg/kg in carrageenan induced animal models. Further screening of the potent extracts of the plant confirmed the presence of xanthone (1, 5-dihydroxy-3, 8-dimethoxy xanthone, m.p.185 0 C, yellowish crystalline needles from methanol) was obtained. The structure of the fraction was confirmed by spectral analysis (UV, IR, NMR). The methanol and aqueous extracts of tubers of Gloriosa superba also possessed good anti-inflammatory in a dose dependent manner i.e 100 mg/kg and 200 mg/kg in carrageenan induced animal models. Further screening of the extracts confirmed the presence of colchicines in the extracts. The present study thus revealed the presence of potent anti-inflammatory drugs in these plants.

Xanthone and benzophenone glycosides from the stems of Cratoxylum formosum ssp. pruniflorum.

Abstract: Two new xanthone glycosides, namely pruniflorosides A and B (1, 2), a new benzophenone glycoside, prunifloroside C (3), and a new xanthone, pruniflorone S (4) were isolated from the stems of Cratoxylum formosum ssp. pruniflorum, along with six known xanthones (5—10). Their structures were determined on the basis of extensive spectroscopic analysis. In addition, their retinoid X receptor α (RXRα) transcriptional activities were evaluated in vitro.

Two Unusual Xanthones from the Bark of Garcinia xanthochymus

Abstract: A new xanthone derivative, garcinexanthone F (1), which was found to possess an α,β-unsaturated γ-lactone moiety, and a new bisxanthone, bigarcinenone B (2), with a terpene bridge providing the xanthonexanthone linkage, were isolated from the bark of Garcinia xanthochymus. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques. The antioxidant assay in vitro showed that compounds 1 and 2 exhibited significant scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical with IC50 values of 22.32 and 20.14 μM, and against HO. radical with IC50 values of 1.16 and 2.85 μM, respectively.

Antifibrotic Constituents from Garcinia mangostana

Abstract: From the CHCl3-soluble fraction of the fruits of Garcinia mangostana (Clusiaceae), six xanthone derivatives, alpha-mangostin (1), gamma-mangostin (2), gartanin (3), deoxygartanin (4), 1-isomangstanin (5) and garcinone E (6), were isolated. All these compounds significantly inhibited HSC-T6 viability as assessed by employing HSC-T6 hepatic stellate cells as an in vitro assay system. Among them, compounds 1 and 2, the most potent and major constituents of G. mangostana, inhibited HSC-T6 viability in dose- and time-dependent manners. In addition, compounds 1 and 2 significantly reduced collagen content, a pathological characteristic of liver fibrosis. Taken together, G. mangostana and its constituents might be beneficial for the treatment of liver fibrosis.

Antiplasmodial constituents from the fruit pericarp of Pentadesma butyracea

Abstract: Bioassay-guided fractionation of the fruit pericarp of Pentadesma butyracea, using the antiplasmodial test, led to the isolation of a new xanthone, named pentadexanthone (1), together with six known compounds: cratoxylone (2), α-mangostin (3), 1,3,5-trihydroxy-2-methoxyxanthone (4), garcinone E (5), (-)-epicathechin (6), and lupeol (7). The structure of 1 was elucidated by spectroscopic data analysis. An antiplasmodial assay was performed with the isolates, in which compounds 1- 3 and 5 exhibited potent activity in vitro against Plasmodium falciparum chloroquine-resistant strain W2, with IC₅₀ values below 3 µM.

New antifungal xanthones from the seeds of Rhus coriaria L

Abstract: Phytochemical investigations of the ethanolic extract of the seeds of Rhus coriaria L. (Anacardiaceae) led to the identification of four new xanthones, characterized as 2,3-dihydroxy-7-methyl xanthone (1), 2,3,6-trihydroxy-7-hydroxymethylene xanthone-1-carboxylic acid (2), 2-methoxy-4-hydroxy-7-methyl-3-O-beta-D-glucopyranosyl xanthone-1,8-dicarboxylic acid (4), and 2-hydroxy-7-hydroxymethylene xanthone-1,8-dicarboxylic acid 3-O-beta-D-glucopyranosyl-(2'-->3")-3"-O-stigmast-5-ene (5), along with the known steroidal glucoside beta-sitosterol-beta-D-glucoside (3). The structures of the isolated compounds have been identified on the basis of spectral data analysis and chemical reactions. All xanthones were active against Aspergillus flavus.