Bangangxanthone A and B, two xanthones from the stem bark of Garcinia polyantha Oliv

Two xanthones, bangangxanthone A (1) [1,5,8-trihydroxy-6'-methyl-6'-(4-methylpent-3-enyl)- pyrano[2',3':3,4]xanthone] and B (2) [1,4,8-trihydroxy-2-prenylxanthone], along with two known xanthones, 1,5-dihydroxyxanthone, 2-hydroxy-1,7-dimethoxyxanthone and the pentacyclic triterpenoids, friedelin, oleanolic acid and lupeol were isolated from the chloroform extract of the stem bark of Garcinia polyantha. The structures of these compounds were assigned by spectroscopic analysis. Compounds 1-4 showed antioxidant DPPH radical scavenging activities.     

Tetraoxygenated xanthones from the fruits of Garcinia cowa

Tetraoxygenated xanthones, cowaxanthones A-E, together with 10 previously reported tetraoxygenated xanthones, were isolated from the crude hexane extract of the fruits of Garcinia cowa. Cowaxanthone B has previously been reported as a synthetic xanthone. Their structures were elucidated by analysis of spectroscopic data, especially by 1D and 2D NMR. The antibacterial activities of the isolated compounds were also evaluated.     

Antimalarial xanthones from Calophyllum caledonicum and Garcinia vieillardii

The antimalarial activity of 22 xanthones against chloroquino-resistant strains of Plasmodium falciparum was evaluated. Natural caloxanthone C (1), demethylcalabaxanthone (2), calothwaitesixanthone (3), calozeyloxanthone (4), dombakinaxanthone (5), macluraxanthone (6), and 6-deoxy-gamma-mangostin (7) were isolated from Calophyllum caledonicum. 1,6-dihydroxyxanthone (8), pancixanthone A (9), isocudraniaxanthone B (10), isocudraniaxanthone A (11), 2-deprenylrheediaxanthone B (12) and 1,4,5-trihydroxyxanthone (13) were isolated from Garcinia vieillardii. Moreover, synthetic compounds (14-22) are analogues or intermediates of xanthones purified from Calophyllum caledonicum (Oger J.M., Morel C., Helesbeux J.J., Litaudon M., Seraphin D., Dartiguelongue C., Larcher G., Richomme P., Duval O. 2003. First 2-Hydroxy-3-Methylbut-3-Enyl substituted xanthones isolated from Plants: structure elucidation, synthesis and antifungal activity. Natural Product Research 17(3), 195-199; Helesbeux J.J., Duval O., Dartiguelongue C., Seraphin D., Oger J.M., Richomme P., 2004. Synthesis of 2-hydroxy-3-methylbut-3-enyl substituted coumarins and xanthones as natural products. Application of the Schenck ene reaction of singlet oxygen with ortho-prenylphenol precursors. Tetrahedron 60(10), 2293-2300). The relationship between antimalarial activity and molecular structure of xanthones has also been explored. The most potent xanthones (2), (3) and (7) (IC50 = c.a. 1.0 microg/mL) are 1,3,7 trioxygenated and prenylated on the positions 2 and 8.     

Prenylated xanthones and tocotrienols from Garcinia virgata

Two xanthones, namely virgataxanthone A and B, have been isolated from the stem bark of Garcinia virgata, together with two formylated tocotrienols and the known delta-tocotrienol, griffipavixanthone and 2,6-dihydroxy-4-methoxybenzophenone (cotoin). Their structures were mainly established using one and two-dimensional NMR and mass spectroscopies. When sufficient material was available, the antioxidant activities of the crude extracts as well as the isolated compounds were evaluated.     

Prenylated xanthones with NGF-potentiating activity from Garcinia xanthochymus

Two prenylated xanthones, 1,4,5,6-tetrahydroxy-7,8-di(3-methylbut-2-enyl)xanthone (1) and 1,2,6-trihydroxy-5-methoxy-7-(3-methylbut-2-enyl)xanthone (2), were isolated from the wood of Garcinia xanthochymus along with a known xanthone, 12b-hydroxy-des-D-garcigerrin A (3). Their structures were elucidated by spectroscopic analysis. Compound 1 (10 muM), 2 (10-30 muM) and 3 (10 muM) showed a markedly enchancing activity of nerve growth factor (NGF)-mediated neurite outgrowth on PC12D cells.     

Xanthones and benzophenones from Garcinia griffithii and Garcinia mangostana

A new polyisoprenylated benzophenone, guttiferone I, together with the known compounds cambogin, 1,7-dihydroxyxanthone, 1,3,6,7-tetrahydroxyxanthone and 1,3,5,6-tetrahydroxyxanthone were isolated from the stem bark of Garcinia griffithii. The acetone extract of the heartwood of Garcinia mangostana contained one new diprenylated xanthone (mangoxanthone) and a new benzophenone (3',6-dihydroxy-2,4,4'-trimethoxybenzophenone) as well as the known xanthones dulxanthone D, 1,3,7-trihydroxy-2-methoxyxanthone, 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran[7,6-b]xanthen-9-one. Their structures were established on the basis of spectroscopic studies and chemical correlation.     

Xanthones from the bark of Garcinia merguensis

The bark of Garcinia merguensis yielded 10 xanthones, merguenone, 1,5-dihydroxy-6'-methyl-6'-(4-methyl-3-pentenyl)-pyrano(2',3':3,2)-xanthone, subelliptenone H, 8-deoxygartanin, rheediaxanthone A, morusignin G, 6-deoxyjacareubin, 1,3,5-trihydroxy-4,8-di(3-methylbut-2-enyl)-xanthone, rheediachromenoxanthone and 6-deoxyisojacareubin. The structure of merguenone was determined using spectroscopic techniques, mainly 1D and 2D NMR spectroscopy.     

Cytotoxic Compounds from the Leaves of Garcinia polyantha

A new compound, named banganxanthone C (=12‐(1,1‐dimethylprop‐2‐en‐1‐yl)‐5,10‐dihydroxy‐9‐methoxy‐2‐methyl‐2‐(4‐methylpent‐3‐en‐1‐yl)‐2H,6H‐pyrano[3,2‐b]xanthen‐6‐one; 4 ), together with five known compounds, were isolated from the leaves of Garcinia polyantha. The structures of the compounds were elucidated on the basis of 1D‐ and 2D‐NMR spectroscopy. Among the known compounds, two were xanthones, one was a pentacyclic triterpene, one sterol, and one benzophenone derivative. Isoxanthochymol ( 2 ) and 4‐[(2E)‐3,7‐dimethylocta‐2,6‐dien‐1‐yl]‐1,5,8‐trihydroxy‐3‐methoxy‐9H‐xanthen‐9‐one ( 3 ) exhibited significant antiproliferative activity against the leukemia cell line TPH‐1 with IC₅₀ inhibition values of 1.5 and 2.8 μg/ml, respectively. The cytotoxic activity was found to be related to apoptosis induction.     

Lanostanes and friedolanostanes from the bark of Garcinia speciosa

The CHCl(3) extract of the bark of Garcinia speciosa contained four 17,14-friedolanostanes and five lanostanes as well as friedelin and common plant constituents. The friedolanostanes were the previously known methyl ester of (24E)-3 alpha,23 alpha-dihydroxy-17,14-friedolanostan-8,14,24-trien-26-oic acid and the methyl esters of three hitherto unknown acids, 3 alpha-hydroxy-16 alpha,23 alpha-epoxy-17,14-friedolanostan-8,14,24-trien-26-oic acid, 3 alpha,23 alpha-dihydroxy-8 alpha,9 alpha-epoxy-17,14-friedolanostan-15-oxo-24-en-26-oic acid and 3 alpha,23 alpha-dihydroxy-17,14-friedolanostan-15-oxo-8(14),24-dien-26-oic acid. New lanostanes were 3 beta,9 alpha-dihydroxylanost-24-en-26-al and the methyl ester of 3 beta-hydroxy-23-oxo-9,16-lanostadien-26-oic acid. Structures were established by analysis of spectroscopic data. In the case of the lanostanes the previously unassigned C-25 stereochemistry was shown to be 25R by X-ray analysis of 3 beta-hydroxy-23-oxo-9,16-lanostadien-26-oic acid. In the case of the friedolanostanes the configuration at C-23 was established as 23R, identical with the absolute configuration at C-23 of mariesiic acids A and B.     

Xanthones from the stem bark of Garcinia nigrolineata

Nine xanthones, nigrolineaxanthones A-I, together with nine known xanthones, were isolated from the crude methanol extract of the stem bark of Garcinia nigrolineata; two of which have previously been reported as synthetic xanthones. The structures were elucidated by analysis of spectroscopic data, especially using 1D and 2D NMR spectroscopic data.     

Xanthones from Garcinia smeathmannii (Oliver) and their antimicrobial activity

Two new xanthones, smeathxanthone A (1) (2-(3,7-dimethyl-2,6-octadienyl)-1,3,5,8-tetrahydroxyxanthone) and smeathxanthone B (2) (5,7,10-trihydroxy-2-methyl-2-(4-methylpent-3-enyl)[2H, 6H]pyrano[3,2-b]xanthen-6-one), have been isolated from the stem bark of Garcinia smeathmannii, and their structures elucidated on the basis of 1D and 2D NMR experiments. 1,3,5-Trihydroxyxanthone and 1,5-dihydroxyxanthone were also obtained. The compounds showed only modest activity against a range of bacteria and yeasts.     

Xanthones from the heartwood of Garcinia mangostana

Twelve xanthones were isolated from the hexane extract of the heartwood of Garcinia mangostana from Myanmar. Their structures were determined using 1D and 2D NMR techniques     

Xanthones from Garcinia cowa Roxb. latex

Five xanthones named cowagarcinone A-E and six previously reported xanthones were isolated from the latex of Garcinia cowa Roxb. Their structures were determined on the basis of spectroscopic analysis. The crude latex and the isolated compounds were investigated for their radical scavenging activities.     

Anti-diabetic xanthones from the bark of Garcinia xanthochymus

An ethyl acetate extract the bark of Garcinia xanthochymus exhibited strong inhibition towards α-glucosidase and PTP1B with IC₅₀ values of 0.3 ± 0.1 μg/mL and 2.3 ± 0.4 μg/mL, respectively. Chemical constituents of the extract were therefore examined, and two new compounds, xanthochymusxanthones A (1) and B (2), along with ten known xanthones (3–12), were isolated. Their structures were determined using spectroscopic methods, mainly 1D and 2D NMR. Inhibitory activity of the isolated compounds was then tested, and subelliptenone F (12) showed significant effect towards α-glucosidase with IC₅₀ value of 4.1 ± 0.3 μM (compared with acarbose, IC₅₀ = 900.0 ± 3.0 μM) whilst xanthochymusxanthone B (2) exhibited remarkable activity towards PTP1B with IC₅₀ value of 8.0 ± 0.6 μM (compared with RK682, IC₅₀ = 4.4 ± 0.3 μM).     

Laurentixanthones A and B, antimicrobial xanthones from Vismia laurentii

A phytochemical investigation of the constituents of the roots of Vismia laurentii has resulted in the isolation of two xanthone derivatives named laurentixanthone A (1) (6-hydroxy-3,3-dimethyl-11-(3-methylbut-2-enyl)pyrano[2,3-c]xanthen-7(3H)-one) and laurentixanthone B (2) (1-hydroxy-5,6,7,8-tetramethoxyxanthone), along with 11 known compounds: 1,7-dihydroxyxanthone, vismiaquinone, vismiaquinone B, bivismiaquinone, 3-geranyloxy-6-methyl-1,8-dihydroxyanthraquinone, O(1)-demethyl-3',4'-deoxypsorospermin-3',4'-diol, 6-deoxyisojacareubin, 1,8-dihydroxy-6-methoxy-3-methylanthraquinone, kaempferol, friedelin and stigmasterol. The structures of compounds were established by means of spectroscopic methods. Furthermore, the compounds were screened for antimicrobial activities in vitro.     

Globulixanthones C,D and E: three prenylated xanthones with antimicrobial properties from the root bark of Symphonia globulifera

Two prenylated xanthone derivatives, named globulixanthones C and D and one bis-xanthone, designated globulixanthone E, have been isolated from the root bark of Symphonia globulifera. The structures of these compounds were elucidated by a detailed spectroscopic analysis. They have been shown to exhibit in vitro significant antimicrobial activity against a range of micro-organisms.     

Phenolic compounds from the flowers of Garcinia dulcis

Dulcisxanthones C-F and dulcinone together with 22 known compounds were isolated from the flowers of Garcinia dulcis. Their structures were determined by spectroscopic methods. The abilities of some of these compounds to act as radical scavengers and antibacterial agents were investigated.     

Illudalane sesquiterpenoids, echinolactones A and B, from a mycelial culture of Echinodontium japonicum

Illudalane sesquiterpenoids, echinolactones A and B, were isolated from the culture broth of the fungus Echinodontium japonicum, and their structures spectroscopically determined.     

Thelephantins A,B and C: three benzoyl p-terphenyl derivatives from the inedible mushroom Thelephora aurantiotincta

Three benzoyl p-terphenyl derivatives named thelephantins A, B and C were isolated from the ethyl acetate extract of fruit bodies of the Thelephoraceous Basidiomycete Thelephora aurantiotincta. Their structures were elucidated by analysis of high-resolution 2D NMR, MS, IR and UV spectra.     

Phenolic compounds from the fruit of Garcinia dulcis

Dulcinoside (1), dulcisisoflavone (2), dulcisxanthone A (3) and sphaerobioside acetate (6) together with 22 known compounds were isolated from the green fruit of G. dulcis. Dulcisflavan (4), dulcisxanthone B (5) and isonormangostin (7) together with 22 known compounds were isolated from the ripe fruit. Compounds 6 and 7 were synthetic known compounds. Their structures were determined by spectroscopic methods. The radical scavenging and antibacterial activities of some of the compounds were investigated.