Prenylated Xanthone Research Articles

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

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 compounds, 3 (α-mangostin, IC50, 0.2 μM) and 11 (3,6-di-O-methyl-α-mangostin, IC50, 0.9 μM), were active. A preliminary analogue development study showed that 3,6-diacetylation and 6-benzoylation both slightly increased the cytotoxicity of α-mangostin (3), whereas methylation reduced such activity. In contrast, neither acetylation, benzoylation, nor methylation enhanced the cytotoxicity of cochinchinone A (6).

Microbial metabolism of α-mangostin isolated from Garcinia mangostana L.

α-Mangostin ( 1), a prenylated xanthone isolated from the fruit hull of Garcinia mangostana L., was individually metabolized by two fungi, Colletotrichum gloeosporioides (EYL131) and Neosartorya spathulata (EYR042), repectively. Incubation of 1 with C. gloeosporioides (EYL131) gave four metabolites which were identified as mangostin 3-sulfate ( 2), mangostanin 6-sulfate ( 3), 17,18-dihydroxymangostanin 6-sulfate ( 4)and isomangostanin 3-sulfate ( 5). Compound 2 was also formed by incubation with N. spathulata (EYR042). The structures of the isolated compounds were elucidated by spectroscopic data analysis. Of the isolated metabolites, 2 exhibited significant anti-mycobacterial activity against Mycobacterium tuberculosis.

A new prenylated xanthone from Garcinia xipshuanbannaensis Y.H. Li

A new prenylated xanthone, named bannaxanthone I (1), has been isolated from the leaves of Garcinia xipshuanbannaensis, along with five other known compounds, bannaxanthone E (2), mangostinone (3), tovophyllin A (4), garcinone E (5), and γ-mangostin (6). The structure of the new compound was elucidated on the basis of high-resolution fast atom bombardment mass spectra (HRFABMS), 1D-and 2D-NMR experiments, including heteronuclear multiple bond connectivity (HMBC), heteronuclear single quantum coherence (HSQC) and 1H–1H-COSY (correlated spectroscopy, COSY).

Antitumor Activity of Some Prenylated Xanthones

Pyranoxanthones 6-8 were obtained by dehydrogenation of the respective dihydropyranoxanthones 3-5 with DDQ in dry dioxane. Two prenylated xanthones 10,11 were obtained from the reaction of 1-hydroxyxanthone (9) with prenyl bromide in alkaline medium, or by condensation of xanthone 9 with isoprene in the presence of orthophosphoric acid. The structural elucidation of the two new compounds 6,11, as well as an update of data for the already described prenylated derivatives 7,8,10 were accomplished by IR, UV, HRMS and NMR (1H, 13C, HSQC and HMBC) techniques. The effect of the prenylated xanthone derivatives on the in vitro growth of human tumor cell lines MCF-7 (breast adenocarcinoma) and NCI-H460 (non-small cell lung cancer) is also reported. Compounds 10 and 11 have been found to exhibit a moderate growth inhibitory activity against the MCF-7 cell line.

Cytotoxic prenylated xanthones from Calophyllum inophyllum

A new prenylated xanthone (1), named caloxanthone N, together with two known constituents, gerontoxanthone C (2) and 2-hydroxyxanthone (3), was isolated from the ethanolic extract of the twigs of Calophyllum inophyllum. Their structures were completely elucidated using a combination of 1D, 2D NMR techniques (COSY, HMQC, HMBC, and ROESY) and HR-ESI-MS analyses. Compounds 1 and 2 exhibited cytotoxicity against chronic myelogenous leukemia cell line (K562) with IC50 values of 7.2 and 6.3 μg ml− 1, respectively.

Constituents of the Cuban Endemic Species Calophyllum pinetorum

A new prenylated xanthone, pinetoxanthone (1), and two new pyranochromanones, pinetoric acid I (2) and pinetoric acid II (3), together with 10 known compounds, namely, the triterpenes friedelin and canophyllol, the xanthone macluraxanthone, the pyranochromanone derivatives calophyllic acid, isocalophyllic acid, calolongic acid, apetalic acid, and isoapetalic acid, and the flavonoids amentoflavone and apigenin, were isolated from the stem bark and leaves of Calophyllum pinetorum, an endemic species in Cuba. The structures of 1-3 were elucidated by spectroscopic methods including 1D and 2D NMR experiments as well as HRESIMS analysis.

Cytotoxicity of Prenylated Xanthones and Other Constituents from the Wood ofGarcinia merguensis

One new prenylated xanthone 5-farnesyltoxyloxanthone B ( 4), three known xanthones alpha-mangostin ( 1), rubraxanthone ( 2) and isocowanol ( 3) as well as (2 E,6 E,10 E)-4beta-hydroxy-3-methyl-5beta-(3,7,11,15-tetramethylhexadeca-2,6,10-tetraenyl)-cyclohex-2-en-1-one ( 5) and 3,3',4- O-trimethylellagic acid were isolated from the wood of GARCINIA MERGUENSIS Wight. The cytotoxic activities of compounds 1 - 5 were evaluated against the MCF-7, MDA-MB-231, NCI-H-460 and SF-268 cell lines with rubraxanthone 2 and 5 exhibiting the highest activity at 9.0 and 12.1 microM, respectively, against MCF-7 cells.

Antiprotozoal Activity Against Plasmodium falciparum. and Trypanosoma cruzi. of Xanthones Isolated from Chrysochlamys tenuis.

One new prenylated xanthone, 1,5-dihydroxy-3-methoxy-4-isoprenylxanthone (1), along with four previously known prenylated xanthones, ananixanthone (2), 1,3,7-trihydroxy-2,4-diisoprenylaxnthone (3), 8-desoxygartanin (4), and toxyloxanthone A (5), have been isolated from Chrysochlamys tenuis. (Hammel) (Clusiaceae). Compound 1 showed moderate activity (31 ± 9 µM) against a chloroquine-resistant strain of Plasmodium falciparum., and compounds 3 and 5 showed the highest antimalarial potency, IC50 = 20 ± 2 and 16 ± 4 µM, respectively. Evaluated against Trypanosoma cruzi., compound 1 presented negligible activity, but compounds 2, 3, and 4 showed mild antitrypanosomal activity with IC50 values of 23 ± 4, 21 ± 5, and 24 ± 3 µM, respectively. All structures were elucidated by NMR spectroscopy in combination with UV, IR, and MS spectral data.

Cytotoxic and Antimalarial Prenylated Xanthones from Cratoxylum cochinchinense

A new prenylated xanthone, 5-O-methylcelebixanthone (1), together with six known compounds; celebixanthone (2), 1,3,7-trihydroxy-2,4-di(3-methylbut-2-enyl)xanthone (3), cochinchinone A (4), alpha-mangostin (5), beta-mangostin (6) and cochinchinone C (7) were isolated from roots of Cratoxylum cochinchinense. Their structures were elucidated by spectroscopic methods. Compounds 2 and 4-7 showed cytotoxic activity against the human lung cancer cell line (NCI-H187) with IC(50) values ranging from 0.65 to 5.2 microg/ml. Compounds 1, 2, 6 and 7 also showed antimalarial activity against Plasmodium falciparum with IC(50) values of 3.2, 4.9, 7.2 and 2.6 microg/ml, respectively.

A prenylated xanthone with antimicrobial activity from the seeds of Symphonia Globulifera

A prenylated xanthone has been isolated from the seeds of Symphonia globulifera together with the known compounds sitosterol and oleanolic acid. The structure of the new compound was elucidated by spectroscopic methods.

Mucigerin, a new coumarin from Calophyllum mucigerum (Guttiferae)

Our recent studies on the stem bark of Calophyllum mucigerum (Guttiferae) have yielded a new coumarin mucigerin, a prenylated xanthone cudraxanthone C and the common steroidal triterpenes friedelin and stigmasterol. Structural elucidations of these compounds were achieved using 1H NMR, 13C NMR, DEPT, COSY, HETCOR and HMBC experiments while MS gave the molecular masses. Cytotoxic assays using CEM-SS cell line (T-lymphoblastic leukemia) on the crude extracts of the stem bark indicated some activity. The crude extracts were also found to be moderately toxic against the larvae of Aedes aegypti. This article reports the isolation and identification of mucigerin as well as bioassay data.

Prenylated xanthones from Garcinia xanthochymus.

A new prenylated xanthone, 1,3,5,6-tetrahydroxy-4,7,8-tri(3-methyl-2-butenyl)xanthone (1), was isolated from the wood of Garcinia xanthochymus together with a known xanthone, garciniaxanthone E (2). Their structures were determined by spectroscopic analysis. Compounds 1 (3 microM) and 2 (10 microM) elicited marked enhancement of nerve growth factor-mediated neurite outgrowth in PC12D cells.

A prenylated xanthone from Allanblackia floribunda

A prenylated xanthone, allanxanthone A, was isolated from Allanblackia floribunda in addition to four known compounds. Its structure was deduced by spectral methods and it was tested for its cytotoxic activity against KB cell line.

Xanthones from hypericum japonicum and H. henryi

From the aerial part of Hypericum japonicum, one new xanthone glycoside, 1,5-dihydroxyxanthone-6- O- β- d-glucoside, one novel dimer xanthone, bijaponicaxanthone, and the first natural prenylated xanthone, 1,3,5,6-tetrahydroxy-4-prenylxanthone, were isolated together with the four known xanthones, 1,5,6-trihydroxyxanthone, isojacereubin, 6-deoxyisojacareubin and 4′,5′-dihydro-1,5,6-trihydroxy-4′,4′,5′-trimethylfurano (2′,3′:4,5) xanthone. Five previously known xanthones, kielcorin, cadensin, 1,7,-dihydroxyxanthone, 1,5-dihydroxy-4-methoxyxanthone and 1,2,5-trihydroxyxanthone were also found in the dichoromethane extract of the stems and leaves of H. henryi. Their structures were elucidated by spectroscopic and chemical methods. Some of the compounds from H. japonicum were found to exert an interesting coagulant activity in an in vitro test. The chemotaxonomic value of xanthones is discussed briefly.

A prenylated xanthone from the bark of symphonia globulifera

One new prenylated xanthone, ananixanthone, was isolated from the bark of Symphonia globulifera The structure was determined by NMR spectroscopy including 2D techniques.

A Highly Prenylated Xanthone from the Bark of Calophyllum Gracilipes (Guttiferae)

A new, highly prenylated xanthone, gracilixanthone (1), was isolated from Calophyllum gracilipes together with three other known xanthones, pyranojacareubin (2), caloxanthone C (3) and trapezifolixanthone (4).

A prenylated xanthone from cell suspension cultures of Hypericum patulum

A new xanthone patulone, 1,2-dihydro-3,6,8-trihydroxy-1,1-bis(3-methylbut-2-enyl)-xanthen-2,9-dione, has been isolated from the callus tissues of Hypericum patulum together with the known compounds 1,3,5,6-tetrahydroxanthone and (−)-epicatechin.