Mary Païs

Depsipeptides from Metarhizium anisopliae

Abstract From the culture medium of a strain of Metarhizium anisopliae , 14 depsipeptides have been isolated. Five of them were identified as known destruxins A, B, C, D and desmethyldestruxin B. The structures of the new compounds, named destruxins E, A 1 , A 2 , B 1 , B 2 , C 2 , D 1 , D 2 and E 1 ,were established mainly from the mass spectral analysis of their corresponding open-chain derivatives.

New nitrogenous and aromatic derivatives from Aglaia argentea and A. forbesii

Seeds and leaves of Aglaia argentea and bark of A. forbesii were extracted. The known cyclopentatetrahydrobenzofuran derivative rocaglaol (1) and the aminopyrrolidine odorine (5), were isolated together with nine new compounds: didesmethylrocaglamide (6), aglains A (7), B (8) and C (9), aglaforbesins A (10) and B (11), ethylrocaglaol (12) and forbaglins A (13) and B (14). Compounds 7–11 and 13,14 possess a new cyclopentatetrahydrobenzopyran and benzoxepine skeleton, respectively, linked to an odorine type moiety. All the structures were elucidated notably by 2D NMR spectroscopy. In addition, the structure of forbaglin A was established by X-Ray crystallographic analysis. Didesmethylrocaglamide revealed strong cytotoxic activity against KB cells (IC50 0.006 μg/ml).

Lapidilectine A and lapidilectine B, two new alkaloids from Kopsia lapidilecta

Abstract Bark and leaves of Kopsia lapidilecta Van der Sleesen were extracted. Two new indole alkaloids were afforded: lapidilectine A 1 (bark) and lapidilectine B 2 (leaves). Both possess a novel skeleton with a five membered unsaturated ring. The structures of these alkaloids were elucidated especially by 2D NMR analysis.

Insecticidal and cytotoxic effects of natural and hemisynthetic destruxins

The insecticidal and cytotoxic effects of 13 natural and hemisynthetic destruxins have been studied. DE shows insecticidal effects similar to those of DA, while DE and DA are more active than all the other natural compounds and analogues tested. Brominated destruxin is a relatively active analogue displaying particular modalities of cytotoxic effects which reflect a certain originality of its mode of action. The linear molecule resulting from the opening of the DA cycle is not toxic. The most hydrophilic destruxins showing e.g. charged radicals (COO-) appear the least toxic probably because they do not penetrate easily the cellular membranes.

Hemisynthesis of rhazinilam analogues: structure - activity relationships on tubulin-microtubule system

Abstract Semi-synthesis of derivatives of rhazinilam, an antitubulin compound, delineated some molecular features necessary for biological activity. In the course of this study, the formation of rhazinilam from 1,2-didehydroaspidospermidine is reexamined and a new mechanism is proposed.

Terengganensines A and B, dihydroeburnane alkaloids from Kopsia terengganensis

Five known indole alkaloids, (+)-quebrachamine, (−)-eburnamine, (+)-isoeburnamine, (−)-eburnaminol and (+)-larutensine, and two new alkaloids, terengganensines A 1 and B 2, possessing a unique dihydroeburnane skeleton were isolated from the bark of Kopsia terengganensis. The structures of the new compounds were elucidated by spectral methods.

Piliostigmin, A 2-phenoxychromone, and C-methylflavonols from Piliostigma thonningii

Abstract Piliostigmin, a 2-phenoxychromone, and three C -methylflavonols, 6,8-di- C -methylquercetin 3-methyl ether, 6- C -methylquercetin 3,7-dimethyl ether and 6,8-di- C -methylquercetin 3,7-dimethyl ether, were isolated from the leaves of Piliostigma thonningii , together with the known compounds quercetin, quercitrin, 6- C -methylquercetin 3-methyl ether, 6- C -methylquercetin 3,7,3′-trimethyl ether, 6,8-di- C -methylkaempferol 3-methyl ether and 6,8-di- C -methylkaempferol 3,7-dimethyl ether. The structures of the new compounds were established by spectral methods, especially 2D NMR. Complete 13 C assignments using HMBC experiments are reported for the four latter C -methylflavonols.

Kurzilactone from Cryptocarya kurzii

Abstract Kurzilactone, a new α,β-unsaturated-δ-lactone, has been isolated from the leaves of Cryptocarya kurzii. The structure of kurzilactone was determined by spectroscopic methods. Kurzilactone exhibits marked cytotoxicity against KB cells (IC50 = 1 μg ml−1).

Phloeodictines A1-A7 and C1-C2, antibiotic and cytotoxic guanidine alkaloids from the new caledonian sponge, Phloeodictyon sp.

Abstract Phloeodictines A1-A7 ( 3a, 3b, 4a, 4b, 4c, 5a, 5b ) and phloeodictines C1-C2 ( 6a, 6b ), new antibacterial and cytotoxic guanidine alkaloids, have been isolated from the sponge Phloeodictyon sp. Their structures were established essentially by mass spectrometry utilizing B/E linked scanning and by 2D NMR experiments.

Cytotoxic cycloartanes from aglaia argentea

Aglaia argentea leaves yielded three new cycloartanes: argenteanones A and B, and argenteanol. The first two possess cytotoxic activity against KB cells (IC50 7.5 micrograms ml-1 and 6.5 micrograms ml-1 respectively). Structural elucidation was done by two-dimensional NMR spectroscopy.