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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), 7α,20(S)-dihydroxy-4,24(28)-ergostadien-3-one (8), 24-methylene-cholest-5-en-3β,7α-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., (Copyright © 2017 Elsevier B.V. All rights reserved.)

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(3H)-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., (Copyright © 2015 Elsevier B.V. All rights reserved.)

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 IC50 values ranging from 6.54 to 18.50μM., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The stem bark of Polyalthia oliveri was screened for its chemical constituents using liquid chromatography high resolution mass spectrometry resulting in the isolation of three indolosesquiterpene alkaloids named 8α-polyveolinone (1), N-acetyl-8α-polyveolinone (2) and N-acetyl-polyveoline (3), together with three known compounds, dehydro-O-methylisopiline (4), N-methylurabaine (5) and polycarpol (6). The structures of the compounds were elucidated by means of high resolution mass spectrometry and different NMR techniques and chemical transformations. Their absolute configurations were assigned by ab-initio calculation of CD and ORD data (for 2 and 3) and X-ray diffraction analysis (for 2). Compounds 2 and 3 exhibited moderate antiplasmodial activity against erythrocytic stages of chloroquine-sensitive Plasmodium falciparum NF54 strain and low cytotoxicity on rat skeletal myoblast (L6) cell line., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Six labdane diterpene derivatives, named turraeanins F-J (3-6, 8) and epi-turraeanin J (7), and a pregnane steroid derivative named turraeasterodionene (2), were isolated by preparative high performance liquid chromatography together with thirteen known compounds from the Cameroonian medicinal plant Turraeanthus africanus. Their structures were elucidated by means of nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry in conjunction with the published data for the analogs, as well as the fragmentation patterns of each compound. Most of the known compounds were obtained for the first time from this plant. The compounds (2-7) were tested for their antibacterial efficacies against both Gram-positive and Gram-negative bacteria, including some clinically-important Risk group 2 human pathogens. Compound 4 exhibited the most pronounced antibacterial effectiveness comparable to standard reference streptomycin, with more potency against Gram-positive than Gram-negative bacteria. By comparing compounds 3, 4 and 5, a tentative structure-activity relationship could be drawn; selected oxidations at C-16 and C-18 drastically reduced the antibacterial efficacy of the parent compound (4). These results revealed the potential of compound 4 as a suitable antibacterial lead compound that might be used for further development of other derivatives to increase the antimicrobial efficacy., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

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 14.8 μM, respectively., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Two polyketides, cryptosporiopsin A (1) and hydroxypropan-2',3'-diol orsellinate (3), and a natural cyclic pentapeptide (4), together with two known compounds were isolated from the culture of Cryptosporiopsis sp., an endophytic fungus from leaves and branches of Zanthoxylum leprieurii (Rutaceae). The structures of these metabolites were elucidated on the basis of their spectroscopic and spectrometric data. Cryptosporiopsin A and the other metabolites exhibited motility inhibitory and lytic activities against zoospores of the grapevine downy mildew pathogen Plasmopara viticola at 10-25μg/mL. In addition, the isolated compounds displayed potent inhibitory activity against mycelial growth of two other peronosporomycete phytopathogens, Pythium ultimum, Aphanomyces cochlioides and a basidiomycetous fungus Rhizoctonia solani. Weak cytotoxic activity on brine shrimp larvae was observed., (Copyright © 2012 Elsevier Ltd. All rights reserved.)