Invertébrés marins du lagon Néo calédonien : 3. Etude structurale de trois nouveaux diterpènes isolés du pennatulaire Cavernulina grandiflora

Three new diterpenes, related to stylatulide but non-balogenated, have been isolated from a new species of sea-pen, Cavernulina grandiflora : cavernuline (1) O-deacetylpropionyl cavernuline (5) and cavernulinine (6). The structures are proposed on the basis of spectral evidence

La girolline, nouvelle substance antitumorale extraite de l'éponge, Pseudaxinyssa cantharella n. sp. (Axinellidae)

Une nouvelle substance antitumorale a été isolée d'une Eponge néo-calédonienne, #Pseudaxinyssa cantharella$. Sa structure a été établie à l'aide de ses caractéristiques spectrales et par préparation de dérivés sélectivement substitués. (Résumé d'auteur

Girolline interferes with cell-cycle progression, but not with translation

Girolline is a 2-aminoimidazole derivative with cytotoxic activity. It affects the survival of exponentially growing leukaemic cultured cells and has a significant antitumour activity on grafted murine tumours in vivo. In vitro studies showed that girolline affected protein synthesis by interfering with the translation termination process. Here, we investigate the effect of girolline on translation termination in human cultured cells. We show that girolline neither induces an increase in translational readthrough of stop codons nor affects the polysome profile in treated cells. This suggests that girolline does not act on translation in vivo. Then, we examine the effect of girolline on cell-cycle progression and we show that girolline induces an arrest of the cell cycle at the G2 stage

Der Nachweis eines Radikalketten-Mechanismus für die Knabe-Reaktion von 1,2-Dihydro-2-methylpapaverin

Die Knabe-Reaktion von 1,2-Dihydro-2-methylpapaverin (9) und die begleitende Eliminierungsreaktion wurden durch ihre gebrochene Reaktionsordnung und durch die Möglichkeit der Inhibition als Radikalkettenreaktionen erkannt, deren kettentragendes Radikal das 3,4-Dimethoxybenzylradikal ist. Die Synthese von N-Methylpavin (19) aus 1,2-Dihydro-2-methylpapaverin (9) ist an die Anwesenheit von Ameisensäure als Inhibitor der Radikalketten gebunden. Durch Zusatz von Inhibitoren können nun Immoniumionen 10 und analoge Verbindungen stabilisiert und ihre Chemie untersucht werden

New Lobane and Cembrane Diterpenes from Two Comorian Soft Corals

Preliminary biological investigation of a collection of Comorian soft corals resulted in the selection of two specimens, one of Sarcophyton and the other of Lobophytum, on the basis of their toxicity on larvae of the brine shrimp (Artemia salina) and inhibition of acetylcholinesterase, respectively. Bioassay-guided fractionations provided a known antitumor promoter cembrane diterpenoid, (+)-sarcophytol-A (1), along with a new lobane diterpenoid, carbomethoxyfuscol (2), from Sarcophyton sp., and a new cembranoid, crassumolide E (3), from Lobophytum sp. The structures of compounds 1–3 were determined by spectroscopic analysis and by comparison of the spectral data with previously reported values. The cembranoid 3 was found to exhibit a moderate inhibitory effect on acetylcholinesterase