Complete assignment of the 1H and 13C NMR spectra of garciniaphenone and keto-enol equilibrium statements for prenylated benzophenones

This article reports the structural elucidation by IR, UV and MS spectroscopic data along with 1H and 13C NMR chemical shift assignments of two benzophenones isolated from the fruit pericarp of Garcinia brasiliensis Mart. (Clusiaceae): garciniaphenone, (1R,5S,7S)-3-benzoyl-4-hydroxy-6,6-dimethyl-5,7-di(3-methyl-2-butenyl)bicyclo[3.3.1]non-3-ene-2,9-dione, a novel triprenylated benzophenone; and 7-epi-clusianone, a tetraprenylated benzophenone that has already been extracted from another species of the same family. Furthermore, the keto-enol tautomeric equilibrium at solution-state was described for these compounds by 1D and 2D NMR spectral methods and one attempt to rationalize the different ratios between the noted tautomers was based on stereochemical features.     

Novel and anti-inflammatory constituents of Garcinia subelliptica

Four novel phloroglucinol derivatives, garcinielliptones A (1), B (2), C (3), D (4), a novel triterpenoid, garcinielliptone E (5), and three known compounds were isolated from the seeds of Garcinia subelliptica. The structures, including relative configurations, were elucidated by means of spectroscopic data. Known compounds garsubellin A (6) and garcinielliptin oxide (7) showed potent inhibitory effects on the release of beta-glucuronidase, and beta-glucuronidase and histamine, respectively, from peritoneal mast cells stimulated with compound 48/80 in a concentration-dependent manner with IC(50) values of 15.6+/-2.5, and 18.2+/-3.6 and 20.0+/-2.7 microM, respectively. Compound 7 showed potent inhibitory effects on the release of beta-glucuronidase and lysozyme from neutrophils stimulated with formyl-Met-Leu-Phe(fMLP)/cytochalasin B (CB) in a concentration-dependent manner with IC(50) values of 15.7+/-3.0 and 23.9+/-3.2 microM, respectively. Compound 7 also showed potent inhibitory effect on superoxide formation from neutrophils stimulated with fMLP/CB also in a concentration-dependent manner with an IC(50) value of 17.9+/-1.5 microM.     

Proteasome-inhibitory and cytotoxic constituents of Garcinia lateriflora: absolute configuration of caged xanthones

A new biflavonoid (1), a new xanthone enantiomer (2), five new caged xanthones (3-7), and several known compounds were isolated from the stem bark of Garcinia lateriflora, collected in Indonesia. The structures of the new compounds were determined by analysis of spectroscopic data, and the absolute configuration of the caged xanthones was shown for the first time at carbons 5, 7, 8, 8a, 10a, and 27, by analysis of COSY and NOESY NMR and ECD spectra. The biflavonoids exhibited proteasome-inhibitory activity, and the known compound, morelloflavone (8) was found to have the greatest potency (IC₅₀=1.3 μM). The caged xanthones were cytotoxic toward HT-29 cells, with the known compound, morellic acid (10) being the most active (ED₅₀=0.36 μM). However, when tested in an in vivo hollow fiber assay, it was inactive at the highest dose tested (20 mg/kg).     

Novel polyisoprenylated benzophenone derivatives from Garcinia paucinervis

Four novel polyisoprenylated benzophenone derivatives, paucinones A-D (1-4), were isolated from the leaves of the plant Garcinia paucinervis. Paucinones A-C (1-3) contained an unexpected cyclohexane-spiro-tetrahydrofuran moiety. A 1-methylene-3,3-dimethylcyclohexane group never reported before was found in the structure of paucinone D (4). The structures of these compounds were elucidated with spectroscopic evidences. The relative stereochemistries of 1-4 were determined by NOESY correlations. These compounds showed significant cytotoxicities against HeLa cells.     

A Highly Rearranged Pentaprenylxanthonoid from the Resin of Garcinia hanburyi

Gamboketanol ( 1 ), a highly rearranged pentaprenylated xanthonoid, two new caged pentaprenylated xanthonoids, gambogefic acid A ( 2 ) and gambogellic acid A ( 3 ), together with two known compounds, were isolated from the acetone extract of the resin of Garcinia hanburyi. Their structures were established on the basis of extensive spectroscopic and mass‐spectrometric analyses. The cytotoxicity of compounds 1 – 3 against HeLa tumor cell line was evaluated, with all of them being modestly active.     

Epunctanone,a New Benzophenone,and Further Secondary Metabolites from Garcinia epunctata Stapf (Guttiferae)

A new polyprenylated benzophenone, named epunctanone ( 1 ), was isolated from the stem bark of Garcinia epunctata Stapf , together with eight known compounds, 7‐epiisogarcinol ( 2 ), 2,6‐dimethoxy‐p‐benzoquinone ( 3 ), friedelin ( 4 ), lupeol ( 5 ), 16β‐hydroxylupeol ( 6 ), betulin ( 7 ), stigmasterol ( 8 ), and rheediaxanthone A ( 9 ). The structure of epunctanone ( 1 ) was established by detailed analysis of its spectroscopic data, especially 1D‐ and 2D‐NMR, and HR‐MS data. All these compounds were evaluated for their antimicrobial and anti‐protozoan activities. They were also assayed to determine if any of the compounds were nonpeptide agonist ligands for nematodal G‐protein‐coupled receptors, which would be an indication of potential antinematodal activity. Among the isolated compounds, 7‐epiisogarcinol ( 2 ) was the most active against Candida albicans.     

莽吉柿中几种双苯吡酮和蒽醌类成分的分离与鉴定

对莽吉柿(Pericarpium Garciniae Mangostanae)85%乙醇提取物进一步分离,得到8个双苯吡酮类化合物和1个蒽酮类化合物,经理化性质和NMR及MS谱学数据鉴定分别为α-倒捻子素-3,6-二乙酸酯（α-mangostin-3,6-diyl diacetate,Ⅰ）、1,5,8-三羟基-3-甲氧基-2,4-双-（3-甲基丁-2-烯）双苯吡酮（8-hydroxycudraxanthone G,Ⅱ）、1,3-二羟基-6,7-二甲氧基-2,8-双-（3-甲基丁-2-烯基）双苯吡酮（Cowaxanthone B,Ⅲ）、1,6-二羟基-3,5-二甲氧基-2-（3-甲基丁-2-烯基）双苯吡酮（Cowaxanthone A,Ⅳ）、1,5-二羟基-4-（3-甲基丁-2-烯基）-6′,6′-二甲基吡喃[2′,3′:3,2]双苯吡酮（trapezifolixanthone,Ⅴ）、1,6-二羟基-6′,6′-二甲基吡喃[2′,3′:7,8]-6″,6″-二甲基吡喃[2″,3″:3,2-]双苯吡酮（brasilixanthone B,Ⅵ）、1,3,5-三羟基-2-（3-甲基丁-2-烯）-4-（1,1-二甲基-2-烯丙基）双苯吡酮（Allanxanthone A,Ⅶ）、1,3,8-三羟基-5-甲氧基-2,4-双-（3-甲基丁-2-烯）双苯吡酮(2,4-di-(3-methylbut-2-enyl)-1,3,8-trihydroxy-5-methoxyxanthone,Ⅷ)、1,4,8-三羟基-6-甲基-3-甲氧基-9,10-蒽酮(1,4,8-trihydroxy-6-methyl-3-methoxy- 9,10-anthraquinone, Ⅸ）。 其中化合物Ⅰ、Ⅴ、Ⅵ、Ⅶ、Ⅸ为首次从藤黄属植物中分离得到,化合物Ⅱ、Ⅲ、Ⅳ、Ⅷ为首次从该植物中分离得到。     

Chemical Constituents from the Bark of Garcinia xanthochymus and Their 1,1‐Diphenyl‐2‐picrylhydrazyl (DPPH) Radical‐Scavenging Activities

A new bis‐xanthone (xanthone=9H‐xanthen‐9‐one), named bigarcinenone A ( 1 ) which is the first example of a bis‐xanthone with the xanthone–xanthone linkage between an aromatic C‐atom and a C₅ side chain from a guttiferae plant, a new phloroglucinol (=benzene‐1,3,5‐triol) derivative, named garcinenone F ( 2 ), together with seven known xanthones were isolated from the bark of Garcinia xanthochymus. Their structures were elucidated by spectroscopic methods, especially 2D‐NMR techniques. Bigarcinenone A ( 1 ) exhibited potent antioxidant activity in the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging test with a IC₅₀ value of 9.2 μM , compared to the positive control, the well‐known antioxidant butylated hydroxytoluene (BHT) with a IC₅₀ of 20 μM (Table 3).     

A novel xanthone dimer derivative with antibacterial activity isolated from the bark of Garcinia mangostana

A novel xanthone dimer derivative, garmoxanthone (1), together with 10 known compounds (2–11), were isolated from bark of Garcinia mangostana. Their structures were established through spectroscopic methods. Garmoxanthone exhibited strong inhibitory activities against MRSA ATCC 43300 and MRSA CGMCC 1.12409 (with MIC values of both 3.9 μg/mL) and moderate activities against tested strains of Vibrio (with MIC values ranging from 15.6 to 31.2 μg/mL). Garmoxanthone is a unique xanthone dimer with linkage of a fused 5/6 ring system and its absolute configuration was elucidated on the basis of experimental and calculated electronic circular dichroism. Garmoxanthone exhibited strong antibacterial activity which partially validated the ethnobotanical use of G. mangostana in the treatment of infections.     

A Novel Xanthone from Garcinia oligantha

One novel xanthone, oliganthone A ( 1 ), was isolated from the stems of the plant Garcinia oligantha. It features the O‐bearing C(3)‐atom and absence of C(4) compared with the structures of related known xanthones, which have never been reported before. The structure of this compound was elucidated by spectroscopic analysis. Compound 1 showed strong HeLa cell growth‐inhibiting effects with IC₅₀ values below 10 μM .