Bruno David

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.

Composition of the flower, leaf and stem essential oils from Laurus nobilis L

The composition of the essential oil from the flowers of Laurus nobilis L. shows differences with the essential oil of the leaves with a high content of β-caryophyllene (10.0%), viridiflorene (12.2%), germacradienol (10.1%), β-elemene (9.7%) and (E)-ocimene (8.0%). Differences between the flower oil and the oils of stem wood and stem bark were also investigated.

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.

A PRELIMINARY CHEMOTAXONOMIC REVIEW OF KOPSIA (APOCYNACEAE)

The present paper is the result of a botanical and chemical study of the Indo-Pacific genus Kopsia (Plumerioideae-Rauvolfieae) Apocynaceae. Some of the species of this genus possess medicinal uses. A survey of the accepted taxa and their synonymy, based on the study of types, is presented. Studies on alkaloids provides chemotaxonomic information. Indeed, in some cases, chemical relationships occur between species belonging to the same botanical group.

Acylated kaempferol glycosides from Laurus nobilis leaves

Abstract Laurus nobilis leaves yielded four non-polar flavonoids: kaempferol -3-O-α- l -(3″,4″- di -E-p- coumaroyl)-rhamnoside , kaempferol -3-O-α- l -(2″,4″- di -E-p- coumaroyl)-rhamnoside , kaempferol -3-O-α- l -(2″-E-p- coumaroyl)-rhamnoside and a new product kaempferol -3-O-α- l -(2″,4″- di -Z-p- coumaroyl)-rhamnoside . Structural elucidation was achieved by UV, 1D- and 2D-NMR experiments, mass spectrometry, acid hydrolysis and saponification.

Alkaloids from leaves and stem bark of Ervatamia polyneura

Abstract Twenty-three alkaloids were isolated from leaves and stem bark of Ervatamia polyneura, four of which are new: vobasenal, 16-epivobasenal, 3-oxo-19-epiheyneanine and 3-hydroxy-3,4-secocoronaridine. The other alkaloids are the known pericyclivine, vobasine, vobasine N-(4)-oxide, 16-epivobasine, vobasinol, dregamine, perivine, anhydrovobasindiol, apparicine, (+) tubotaiwine, voaphylline, 3, 14-dihydroellipticine, coronaridine, eglandine, eglandulosine, heyneanine, 19-epiheyneanine, voacangine and coronaridinehydroxyindolenine. Structural elucidation of the new alkaloids was based on spectral data.

A new flavonol glycoside from Catharanthus roseus

Abstract A new flavonol glycoside was isolated together with two known flavonoids from the stems of Catharanthus roseus (Apocynaceae). Its structure was established as syringetin-3- O -robinobioside by means of UV, MS and NMR data, especially two dimensional experiments.

Sulphated steroidal derivatives from Ruscus aculeatus

Abstract Two novel steroidal derivatives, (1β-hydroxyruscogenin 1-sulphate and 26-O-β- d -glucopyranosyl furost-5-en-1β,22ζ-triol 1-sulphate) were isolated from the rhizome of Ruscus aculeatus . The structures were established by spectroscopic methods.

Alkaloids from the leaves and stem bark of Ervatamia malaccensis

Abstract Chemical investigation of the leaves and stem bark of Ervatamia malaccensis afforded two novel alkaloids, N (1)-methoxymethuenine and N (1)-methoxy-19,20-dehydroervatamine together with the known alkaloids: 19,20-dehydroervatamine, 20-epiervatamine, methuenine, 16-epimethuenine, 6-oxomethuenine and dregamine. Structural elucidation of the new alkaloids was based on spectral data and on a chemical correlation.

Volatile constituents from leaves and wood of Leea guineensis G. Don (Leeaceae) from Cameroon

The volatile constituents from wood and leaves of Leea guineensis G. Don were obtained by hydrodistillation and analysed by GC-MS. This analysis indicated the presence of 69 compounds, which have never been described in this plant.