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Chemical investigation of the roots of Entandrophragma congoënse (Meliaceae) led to the isolation of two new 3,4- seco -tirucallane triterpenes, namely seco -tiaminic acids B and C ( 1 and 2 ) together with nine known compounds: 3,4-secotirucalla-21-formyl-23-oxo-4(28),7,24-trien-3-oic acid ( 3 ), methyl angolensate ( 4 ), molucensin N ( 5 ), molucensin O ( 6 ), piscidinol A ( 7 ), 7 α ,20( S )-dihydroxy-4,24(28)-ergostadien-3-one ( 8 ), 24-methylene-cholest-5-en-3 β ,7 α -diol ( 9 ), entilin A ( 10 ), and entilin B ( 11 ). Their structures were determined using extensive spectroscopic methods including 1D and 2D NMR, HRMS, and CD analyses; new results were compared to existing data in the literature. The two newly identified seco -tiaminic acids showed moderate antiplasmodial and cytotoxic activities against a chloroquine-sensitive strain of the malaria parasite ( Plasmodium falciparum NF54) and were cytotoxic toward an L6 rat skeletal myoblast cell line, respectively. [ABSTRACT FROM AUTHOR]

Introduction The genus Quassia is a promising source of secondary metabolites with biological potential including antimalarial and cytotoxic activities. Limited data are available on the phytochemistry and pharmacology of Quassia silvestris Cheek & Jongkind, a Cameroonian medicinal plant used to treat various ailments. Objectives To carry out the bioassay-guided fractionation and LC-HR-ESI-MS analyses of the leaves extract from Q. silvestris; to purify the active fractions and isolate the major compounds using different chromatographic and spectroscopic methods. The obtained compounds will be evaluated for their biological activity. Material and methods Following the cytotoxic screening and LC-HR-ESI-MS profiling of fractions obtained from partition of the methanolic extract of Q. silvestris leaves, the CH2Cl2-soluble fraction which exhibited the highest cytotoxicity was retained for further investigations. Results Sixteen squalene-derived metabolites were identified with oxasqualenoid derivatives being the most predominant. Among the isolates, structure elucidation of two new oxasqualenoids quassiols E (1) and F (2), were achieved by NMR (one-dimensional (1D) and two-dimensional (2D)) and MS methods. The newly characterised compounds 1 and 2, together with the known tetraol (3) and 3-oxo-oleanoic acid (16) displayed moderate cytotoxicity. Conclusion The identification and structural characterisation of highly oxidised squalene derived metabolites from this plant may provide important insight data for further pharmacological investigations. The LC-HR-ESI-MS n method reported here could be developed as a rapid and efficient tool for the analyses of structurally related compounds in the genera Quassia, Simarouba, and Eurycoma of the subfamily Simarouboideae. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Bioassay guided fractionation of Hypericum riparium leaves extract has resulted in the isolation and characterization of three new compounds namely chipericumin E ( 1 ), hyperenone C ( 3 ), and hyperixanthone ( 5 ), together with twenty known compounds. Their structures were elucidated based on comprehensive interpretation of spectroscopic and spectrometric data. Compounds 1 – 4 , and 6 – 8 displayed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and cytotoxic effects on the human gastric cell line BGC-823 with IC 50 values ranging from 6.54 to 18.50 μM. [ABSTRACT FROM AUTHOR]

Abstract: Two unusual dibenzofurans, preussiafurans A–B (1–2), together with six known compounds have been isolated from the fungus Preussia sp. occurring in Enantia chlorantha Oliv. The structures were established on the basis of 1D and 2D NMR spectroscopy and MS analysis. Compounds 1–4 showed antiplasmodial activity against erythrocytic stages of chloroquine-resistant Plasmodium falciparum (NF54) and moderate cytotoxicity on L6 cell lines with IC50 values of 8.67 and 14.8μM, respectively. [Copyright &y& Elsevier]

In the search for new compounds to protect plants from fungi, an endophytic fungus, Epicoccum sp. CAFTBO, obtained from Theobroma cacao was found to produce three polyoxygenated polyketides, namely epicolactone ( 1) and epicoccolides A ( 2) and B ( 3), together with seven known metabolites. The structures of these compounds were elucidated by a combination of detailed spectroscopic and spectrometric analyses as well as DFT calculations of the electronic circular dichroism spectra and the single-crystal X-ray diffraction analysis of 1. Compounds 1- 3 showed potent antimicrobial activities and significant inhibitory effects on the mycelial growth of two peronosporomycete phytopathogens, Pythium ultimum and Aphanomyces cochlioides, and the basidiomycetous fungus Rhizoctonia solani. [ABSTRACT FROM AUTHOR]

Abstract: In our search for secondary metabolites regulating the motility behavior of zoospores of the grapevine downy mildew pathogen Plasmopara viticola, we found that extracts from an endophytic fungus Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides remarkably impaired motility of zoospores followed by lysis. The active principles in the extracts were isolated and identified as two new compounds, namely excelsional (1a) and 9-hydroxyphomopsidin (2a), together with excelsione (1b), phomopsidin (2b), alternariol (3a), alternariol-5-O-methyl ether (3b), the hitherto undescribed 5′-hydroxyalternariol (3c), altenusin (4) from the fungus, xanthochymol (5) and 1,5-dihydroxy-3-methoxyxanthone (mesuaxanthone, 6) from the plant. Bioassays revealed that compounds 1a/b, 2a/b, and 3a–6 displayed motility inhibition and lytic activities against zoospores of the grapevine downy mildew pathogen P. viticola in a dose- and time-dependent manner from 1 to 10μg/mL. Their structures were elucidated by extensive spectroscopic analyses including 2D NMR techniques. This is the first report of an endophyte and its natural products from E. calophylloides and the first isolation of compounds 5 and 6 from this plant. [Copyright &y& Elsevier]

Si-enterobactin (2a), a hexacoordinated complex of the siderophore enterobactin (2b) with silicon as the central atom, was isolated from an endophytic Streptomyces sp. occurring in Piper guinensis roots. The structure and absolute configuration were determined from NMR and MS data, and by X-ray diffraction. The orientation of the molecule along the pseudo-3-fold axis shows that the coordination environment of the silicon atom complexed with three bidentate ligands is Δ. We assume that 2a or related complexes may be involved in the transport of silicon in plants, diatoms, or other silicon-dependent organisms. [ABSTRACT FROM AUTHOR]

Chaetosidone A (I), a new depsidone, is isolated from a culture of Chaetomium sp. [ABSTRACT FROM AUTHOR]

A mixture of two compounds with potent antiplasmodial activity in vitro against the W2 strain of Plasmodium falciparum (half maximal inhibitory concentration, 1.12 μg/mL) was obtained in a previous investigation of the CH2Cl2-MeOH extract of the seeds of Salacia longipes var. camerunensis. Separation by column chromatography led now to the isolation of salaterpene E ( 1) and (1 R,2 R,4 S,5 S,6 R,7 R,9 S,10 R)-2-acetoxy-1,6,9-tribenzoyloxy-4-hydroxy-dihydro- β-agarofuran ( 2). The structure of 1 was elucidated by spectroscopic analysis, and its absolute configuration was established unambiguously by means of single-crystal X-ray diffraction. Also the absolute configurations of the recently described salaterpenes A ( 2a) and D ( 2b) were determined by this method using the anomalous scattering of the oxygen atoms only. [ABSTRACT FROM AUTHOR]

Two new tirucallane-type triterpenoids were isolated from the bark of Entandrophragma congoënse (Meliaceae) along with five known compounds gladoral A, bipendensin, 4-hydroxymethyl-3,5-dimethyldihydrofuran-2(3 H )-one, scopoletin and 5,7-dimethoxy-6-hydroxycoumarin. Their structures were elucidated by means of spectroscopic analyses including 1D and 2D-NMR spectroscopy, high resolution mass spectrometric data as well as the comparison of data with those reported in the literature. The tested compounds ( 1 – 4 ) displayed moderated antiplasmodial activity against erythrocytic stages of chloroquine-resistant Plasmodium falciparum strain NF54 and low cytotoxicity on L6 cell lines. All the isolated compounds are reported for the first time from the genus Entandrophragma. [ABSTRACT FROM AUTHOR]