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.     

红厚壳枝条的化学成分

从红厚壳(Calophyllum inophyllum Linn.)枝条乙醇提取物中分离得到11个化合物,通过光谱分析,鉴定其结构为:6-羟基-2,3-二甲氧基 酮 ( 1 ) ,1,3,7-三羟基 酮 ( 2 ) ,1,3,7-三羟基-8-甲氧基 酮( 3 ) ,7-羟基-1,3-二甲氧基 酮( 4 ) ,伪蒲公英甾醇( 5 ) ,1,3,6-三羟基-5,7-二甲氧基 酮( 6 ) ,2-羟基-1-甲氧基 酮 ( 7 ) ,2-羟基-1,8-二甲氧基 酮 ( 8 ) ,1,3,5-三羟基-2-甲氧基 酮 ( 9 ) ,4-羟基 酮 ( 10 ) ,1,3,5-三羟基 酮 ( 11 ) 。化合物 2 ~ 5 为首次从红厚壳属植物中得到,化合物 6 ~ 8 为首次从该植物中得到,化合物 1 为一新的天然产物。细胞毒活性测试结果表明,化合物 9 对人胃癌细胞(SGC-7901)的增殖显示出生长抑制活性, 其IC₅₀值为1.8×10^-5 mol/L。     

Tomoeones A-H, cytotoxic phloroglucinol derivatives from Hypericum ascyron

Phloroglucinol derivatives tomoeones A-H (1-8) and three known compounds were isolated from leaves of Hypericum ascyron. Their structures were established based on spectroscopic analyses. They are all acylphloroglucinol derivatives possessing a spiro skeleton with geminal isoprenyl groups and a monoterpene moiety, and they are stereoisomers to each other at C-4 and C-13. They appear to be a class of phloroglucinol derivatives. Cytotoxicities of the isolated phloroglucinol derivatives against human tumor cell lines, including multidrug-resistant (MDR) cancer cell lines, were evaluated. Tomoeone F (6) demonstrated significant cytotoxicity against KB cells with an IC50 value of 6.2 microM. Compound 6 was also cytotoxic against MDR cancer cell lines (KB-C2 and K562/Adr), which was more potent than doxorubicin.     

Biologically active alkylated coumarins from Kayea assamica

Four coumarin derivatives, theraphins A (1), B (2), C (3), and D (4), along with three known xanthones, 2-hydroxyxanthone, 1,7-dihydroxyxanthone, and 5-hydroxy-1-methoxyxanthone, were isolated from the bark of Kayea assamica (Clusiaceae) native to Myanmar. Their structures were determined using spectroscopic and chemical techniques. The absolute configuration of 1 was established by the modified Mosher ester method. Theraphins A (1), B (2), and C (3) exhibited good cytotoxicity against Col2, KB, and LNCaP human cancer cell lines. Theraphin D (4) showed mild activity only against the KB cell line. The coumarins also exhibited mild antimalarial activities.     

Composition of fatty acids triacylglycerols and unsaponifiable matter in Calophyllum calaba L. oil from Guadeloupe

The composition of the kernel oils of two Calophyllum species (Calophyllum calaba L. and Calophyllum inophyllum L.) was investigated. The physico-chemical properties and fatty acid composition of the kernel oils were examined. In two species, oleic acid C18:1 (39.1-50%) is the dominating fatty acid followed by linoleic acid C18:2 (21.7-31.1%) as the second major fatty acid. Stearic C18:0 (13.4-14.3%) and palmitic C16:0 (11-13.7%) acids are the major saturates. The oils contains an appreciable amount of unsaturated fatty acids (70.8-73.10%). Most of the fatty acids are present as triacylglycerol (76.7-84%), twenty one triacylglycerols are detected with predominantly unsaturated triacylglycerols. The total unsaponifiable content, its general composition and the identity of the components of the sterol and tocopherol fractions are presented. In both species, analysis of the unsaponifiable fractions revealed the preponderance of phytosterols, mainly stigmasterol (35.8-45.1%) and beta-sitosterol (41.1-43.1%). Among the eight tocopherols and tocotrienols present in two species, variations exist; alpha-tocopherol (183 mg/kg) is the main tocopherol in Calophyllum calaba L. and Delta-tocotrienol (236 mg/kg) is the dominant tocotrienol in Calophyllum inophyllum L.     

Xanthones from Hypericum chinense

Six xanthones, 1,3,7-trihydroxy-2-(2-hydroxy-3-methyl-3-butenyl)-xanthone (1), 1,7-dihydroxy-2,3-[2'-(1-hydroxy-1-methylethyl)-dihydrofurano]-xanthone (2), 1,3,7-trihydroxy-5-methoxyxanthone (3), 1,7-dihydroxy-5,6-dimethoxyxanthone (4), 4,5-dihydroxy-2,3-dimethoxyxanthone (5), 1,3-dihydroxy-2,4-dimethoxyxanthone (6) and 21 known xanthones were isolated from the leaves and stems of Hypericum chinense. Their structures were established based on spectroscopic studies.     

Antibacterial and cytotoxic xanthones from the roots of Cratoxylum formosum

Chemical investigation of the roots of Cratoxylum formosum has resulted in the isolation and characterization of xanthones: three new, named formoxanthone A-C and three known together with three known anthraquinones. Their structures were established on the basis of analysis of spectroscopic evidence. In addition, antibacterial and cytotoxic activities of the isolates were also evaluated.     

A polyisoprenylated ketone from Calophyllum enervosum

A polyisoprenylated ketone named enervosanone has been isolated from the stem bark of Calophyllum enervosum together with three known compounds, cambogin, osajaxanthone and epicatechin. Their structures were determined by spectroscopic analysis. The antimicrobial evaluations of the isolated compounds were also reported.     

Xanthone derivatives from Cratoxylum cochinchinense roots

Two xanthones and two caged-prenylated xanthones, named cochinchinones A-D, respectively, and a synthetically known caged-prenylated xanthone, together with seven known compounds were isolated from the roots of Cratoxylum cochinchinense (Lour.) Blume. Their structures were assigned on the basis of analyses of spectroscopic data. Some of the compounds exhibited effective antioxidative properties.     

Acylphloroglucinol and xanthones from Hypericum ellipticum

An acylphloroglucinol, elliptophenone A, and two xanthones, elliptoxanthone A and elliptoxanthone B, were isolated from the aerial portions of Hypericum ellipticum together with three known xanthones, 1,3,7-trihydroxy-8-(3-methyl-2-butenyl)-9H-xanthen-9-one, 1,6-dihydroxy-4-methoxy-9H-xanthen-9-one, and 1,4,5-trihydroxy-9H-xanthen-9-one. Their structures were determined by spectroscopic analyses. The acylphloroglucinol and xanthones were evaluated for cytotoxicity using three human colon cancer cell lines cell lines (HT-29, HCT-116 and Caco-2) and a normal human colon cell line (CCD-18Co).     

Albizosides D and E, two new cytotoxic triterpene saponins from Albizia chinensis

Two oleanane-type triterpene saponins, named albizosides D and E (1 and 2), together with a known compound, Julibroside J₈ (3), were isolated from the stem bark of Albizia chinensis. The structures of compounds 1 and 2 were established by 1D, 2D NMR experiments, and chemical methods, and they showed moderate cytotoxic activity against a small panel of human tumor cell lines.     

Two-step biodiesel production from Calophyllum inophyllum oil: Optimization of modified β-zeolite catalyzed pre-treatment

In this study, a two-step process was developed to produce biodiesel from Calophyllum inophyllum oil. Pre-treatment with phosphoric acid modified β-zeolite in acid catalyzed esterification process preceded by transesterification which was done using conventional alkali catalyst potassium hydroxide (KOH). The objective of this study is to investigate the relationship between the reaction temperatures, reaction time and methanol to oil molar ratio in the pre-treatment step. Central Composite Design (CCD) and Response Surface Methodology (RSM) were utilized to determine the best operating condition for the pre-treatment step. Biodiesel produced by this process was tested for its fuel properties.     

Homoisoflavonoids and xanthones from the tubers of wild and in vitro regenerated Ledebouria graminifolia and cytotoxic activities of some of the homoisoflavonoids

Eleven homoisoflavonoids and two xanthones were isolated and characterized from the bulbs of Ledebouria graminifolia. Five of the homoisoflavonoids are new compounds and were identified as: 5-hydroxy-7-methoxy-3-(4'-hydroxybenzyl)-4-chromanone, 5-hydroxy-6,7-dimethoxy-3-(4'-hydroxybenzyl)-4-chromanone, 5,7,8-trimethoxy-3-(4'-hydroxybenzyl)-4-chromanone, 5-hydroxy-3',4',7-trimethoxyspiro[2H-1-benzopyran-7'-bicyclo[4.2.0]octa-trien]-4-one, 5,7-dihydroxy-3',4'-dimethoxyspiro[2H-1-benzopyran-7'-bicyclo[4.2.0]octa-trien]-4-one. Structures were elucidated by extensive 1D, and 2D NMR spectroscopy and HRMS. A method for tissue culture was developed and the bulbs of mature plants were found to contain all the compounds isolated from the wild specimens of L. graminifolia.     

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.     

Ellagic acid derivatives and cytotoxic cucurbitacins from Elaeocarpus mastersii

Bioassay-guided investigation of the bark of Elaeocarpus mastersii using KB (human oral epidermoid carcinoma) cells as a monitor led to the isolation of two cucurbitacins, cucurbitacin D and cucurbitacin F as cytotoxic principles, together with two ellagic acid derivatives, 4'-O-methylellagic acid 3-(2",3"-di-O-acetyl)-alpha-L-rhamnoside (1) and 4,4'-O-dimethylellagic acid 3-(2",3"-di-O-acetyl)-alpha-L-rhamnoside (2). These compounds were evaluated against a panel of human tumor cell lines.     

A new quinoline derivative with cytotoxic activity from Streptomyces sp. neau50

A new quinoline derivative, methyl 8-(3-methoxy-3-methylbutyl)-2-methylquinoline-4-carboxylate (1), was isolated from the endophytic strain Streptomyces sp. neau50, and the structure was elucidated by extensive spectroscopic analysis. Compound 1 showed cytotoxicity against human lung adenocarcinoma cell line A549 with an IC₅₀ value of 29.3 μg mL⁻¹.     

Withanolides from Withania aristata and their cytotoxic activity

Seven new withanolides (1-7), along with three known ones (8-10), were isolated from the leaves of Withania aristata. Their structures were elucidated on the basis of spectroscopic analysis, including 2D NMR experiments and spectrometric techniques, and the absolute configuration of 1 and 2 was established by CD analysis. In the search for new cytotoxic compounds from Withania species, the isolated compounds 1-9, along with two derivatives, were assayed for their cytotoxicity against HeLa, MCF-7 and A-549 human tumor cell lines. Derivative (4S,20R,22R)-27-acetoxy-4-p-bromobenzoyloxy-1-oxo-witha-2,5,16,24-tetraenolide (13) showed cytotoxicity against all the cell lines assayed with IC₅₀ values ranging from 2.8 to 3.6 μM, and (4S,20R,22R)-4,27-diacetoxy-4-hydroxy-1-oxo-witha-2,5,16,24-tetraenolide (12) exhibited an IC₅₀ value of 5.4 μM on the MCF-7 cell line.     

Antiprotozoal and cytotoxic naphthalene derivatives from Diospyros assimilis

Chemical investigation of the roots of Diospyros assimilis had led to the isolation and characterization of six naphthalene derivatives, two 2-naphthaldehyes, namely 4-hydroxy-3,5-dimethoxy-2-naphthaldehyde 1, 4-hydroxy-5-methoxy-2-naphthaldehye 2, its related isomer 5-hydroxy-4-methoxy-2-naphthaldehyde 3 and three commonly occurring naphthoquinones, diospyrin 4, 8'-hydroxyisodiospyrin 5 and the simple monomer, plumbagin 6. Their chemical structures were established by detailed NMR investigations including 1H and 13C NMR, HSQC, HMBC and NOESY experiments. In addition, the naphthalene derivatives 1-5 were evaluated for their in vitro antiprotozoal activity against protozoan parasites belonging to the genera Trypanosoma, Leishmania and Plasmodium. Among the tested compounds, naphthaldehyde 1 showed moderate inhibition of the growth of the parasites, T. brucei, T. cruzi, L. donovani with IC50 values of 19.82, 12.28 and 38.78 microM and displayed cytotoxicity towards rat skeletal myoblasts (L-6 cells) with IC50 of 174.94 microM, while 2 and 3 were found to be comparatively less active to 1. The dimeric quinones 4 and 5 exhibited good activity against T. brucei and L. donovani with IC50 of 1.12 and 8.82 microM and 12.94 and 16.66 microM respectively.