A New Ceramide and Biflavonoid from the Leaves of Parinari hypochrysea (Chrysobalanaceae).

A new ceramide and a new biflavonoid named parinaramide (1) and sparinaritin (2), respectively, have been isolated along with ten known compounds, kaempferol, quercetin, taxifolin, taxifolin-3-O-rhamnoside, lupeol, betulinic acid, ursolic acid, 2α-hydroxy-ursolic acid, 2,3-dihydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-propanone, and sucrose, from the leaves of Parinari hypochrysea (Chrysobalanaceae). Structures were determined using 1D- and 2D-NMR, MS and by chemical analysis. The methanol extract of leaves, stem bark and roots of P. hypochrysea were screened for their antioxidant and lipoxygenase inhibition potential and found to be inactive.

Cytotoxicity of four Aframomum species (A. arundinaceum, A. alboviolaceum, A. kayserianum and A. polyanthum) towards multi-factorial drug resistant cancer cell lines.

BACKGROUND: The search for natural products as potential cytotoxic agents has yielded promising candidates. However multidrug resistance (MDR) is still a major hurdle for patients receiving chemotherapy. In the present study, we evaluated the cytotoxicity of the methanol extracts of four dietary Aframomum plant species (A. arundinaceum, A. alboviolaceum, A. kayserianum and A. polyanthum) against nine sensitive and MDR cancer cell lines. We have also identified the bioactive constituents of A. arundinaceum. METHODS: The cytotoxicity of the methanol extracts of the above plants was determined using a resazurin reduction assay. Chromatographic techniques were used to isolate the constituents of A. arundinaceum. RESULTS: A preliminary experiment on leukemia CCRF-CEM cells at 40 µg/mL showed that the extracts from A. kayserianum and A. alboviolaceum as well as the isolated compounds namely compounds aframodial (1), 8(17),12-labdadien-15,16-dial (2), galanolactone (3), 1-p-menthene-3,6-diol (6) and 1,4-dimethoxybenzene (7) were less active, inducing more than 50% growth of this cell line contrary to A. polyanthum and A. arundinaceum extracts, galanals A (4) and B (5), naringenin (8) and kaempferol-3,7,4'-trimethylether (9). The IC50 values below or around 30 µg/mL were recorded with A. arundinaceum extract against eight of the nine tested cancer cell lines. This extract as well as compound 8 displayed IC50 values below 40 µg/mL towards the nine tested cancer cell lines whilst A. polyanthum extract, compounds 4, 5 and 9 showed selective activities. Collateral sensitivity (hypersensitivity) was observed with A. arundinaceum extract towards leukemia CEM/ADR5000 cells and glioblastoma U87MG.ΔEGFR compared to their respective sensitive counterparts CEM/CEM and U87MG. CONCLUSION: The results of this study provide evidence of the cytotoxicity selected Aframomum species as well as a baseline information for the potential use of Aframomum arundinaceum in the fight against drug sensitive and otherwise drug-resistant cancers.

Unambiguous Determination of the Absolute Configuration of Dimeric Stilbene Glucosides from the Rhizomes of Gnetum africanum.

Dimeric stilbene glucosides 1-3 [two diastereomers of (-)-gnemonoside A (1a and 1b), (-)-gnemonoside C (2), and (-)-gnemonoside D (3)] as well as a mixture of the two enantiomers of gnetin C (4) were isolated from the rhizomes of Gnetum africanum. The two enantiomers of gnetin C, (+)-4 and (-)-4, were obtained from the aglycones of 1a and 1b, respectively. The configurations of these stilbenoids were investigated by NMR and vibrational circular dichroism (VCD) experiments. The absolute configurations of (-)-1a, (-)-2, (-)-3, and (-)-4 were established as 7aS,8aS by VCD spectroscopy in combination with density functional theory calculations. The antiamyloidogenic activity of the isolated stilbenes was also evaluated versus beta-amyloid fibrils. The four glucosides of gnetin C (1a, 1b, 2, and 3) were found to be the most active compounds, with inhibition percentages of 56, 56, 58, and 54 at 10 µM, respectively.

Sonhafouonic acid, a new cytotoxic and antifungal hopene-triterpenoid from Zehneria scabra camerunensis.

A new hopene-type triterpenoid, namely sonhafouonic acid 1a was isolated from Zehneria scabra camerunensis, together with eight known compounds. The structure of 1a was established by extensive NMR and high resolution MS techniques and confirmed by single-crystal X-ray crystallographic analysis. Compound 1a exhibited inhibitory activity against mycelial growth of two peronosporomycete phytopathogens Pythium ultimum and Aphanomyces cochliodes and cytotoxicity towards brine shrimp larvae (Artemia salina) at 10 µg/mL.

Phosphodiesterase I-inhibiting Diels-Alder adducts from the leaves of Morus mesozygia.

A new 2-arylbenzofuran derivative, (+)-dimethylsmoracin O (1), and three new Diels-Alder type adducts, mesozygins A­C (2­4), in addition to eight known compounds, artonin I (5), chalcomaracin (6), norartocarpetin (7), moracin L (8), mulberrofuran F (9), moracin M (10), moracin C (11), and morachalcone A (12),were isolated from the leaves of Morus mesozygia Stapf. Structures were elucidated by spectroscopic data analyses. Compounds 2-7 displayed a potent phosphodiesterase I inhibitory activity.

Antimicrobial activities of the methanol extract and compounds from Artocarpus communis (Moraceae).

BACKGROUND: Artocarpus communis is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antimicrobial activities of the methanol extract (ACB) and compounds isolated from the bark of this plant, namely peruvianursenyl acetate C (1), α-amyrenol or viminalol (2), artonin E (4) and 2-[(3,5-dihydroxy)-(Z)-4-(3-methylbut-1-enyl)phenyl]benzofuran-6-ol (5). METHODS: The liquid microdilution assay was used in the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC), against seven bacterial and one fungal species. RESULTS: The MIC results indicated that ACB as well as compounds 4 and 5 were able to prevent the growth of all tested microbial species. All other compounds showed selective activities. The lowest MIC value of 64 µg/ml for the crude extract was recorded on Staphylococcus aureus ATCC 25922 and Escherichia coli ATCC 8739. The corresponding value of 32 µg/ml was recorded with compounds 4 and 5 on Pseudomonas aeruginosa PA01 and compound 5 on E. coli ATCC 8739, their inhibition effect on P. aeruginosa PA01 being more than that of chloramphenicol used as reference antibiotic. CONCLUSION: The overall results of this study provided supportive data for the use of A. communis as well as some of its constituents for the treatment of infections associated with the studied microorganisms.

Hepatoprotective and antioxidant arylbenzofurans and flavonoids from the twigs of Morus mesozygia.

The chemical investigation of the twigs of Morus mesozygia resulted in the isolation of three new prenylated 2-arylbenzofurans, named moracin KM, LM, and SC (1-3), nine known 2-arylbenzofurans (4-12), and two known flavonoids (13-14). The structures of the new compounds were established as [2'',3'':6,7]-(6-(S)-hydroxymethyl-6-methylpyrano)-2-(3,5-dihydroxyphenyl)benzofuran-5-ol (1), [2'',3'':6,7]-(4,7-dihydro-6-methyloxepine)-2-(3-hydroxy-5-methoxyphenyl)benzofuran-5-ol (2), and [2'',3'':6,7]-(6,6-dimethylpyrano)-2-(3,5-dihydroxyphenyl)benzofuran (3). One of the new compounds, moracin LM (2), displayed modest antioxidant activity, whereas known compounds 4, 13, and 14 showed significant hepatoprotective and antioxidant activities.

New stilbene dimers against amyloid fibril formation.

Twenty stilbene derivatives and moracin M extracted from natural products were tested against amyloid-beta peptide (Abeta) aggregation. Results of stilbene monomer derivatives indicated that interaction with resveratrol and piceid was specific. Concerning oligomers, scirpusin A and epsilon-viniferin glucoside demonstrated a strong inhibition of the aggregation process.

Prenylated arylbenzofuran derivatives from Morus mesozygia with antioxidant activity.

Five prenylated arylbenzofurans, moracins Q-U, were isolated from Morus mesozygia (Moraceae). Their structures were elucidated on the basis of spectroscopic evidence. Along with these compounds, 3beta-acetoxyurs-12-en-11-one, marsformoxide, moracin C, moracin M, moracin K, artocarpesin, cycloartocarpesin, morachalcone A were also isolated. Four of the five compounds, (moracins R-U) displayed potent antioxidant activity.