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Phytochemical investigation of barks of Christiana africana led to the identification of cyclopeptide alkaloids, flavonoids, coumarinolignans, iridoids, sesquiterpenoids, and triterpenes. This plant was classified so far in the Tiliaceae family. This study was started while the genomic study of numerous specimens was described in order to establish new criteria for Malvales botanical classification. In the present work, twenty components were identified, belonging to the three major classes of secondary metabolites: alkaloids, phenols, and terpenes. In the first class, cyclopeptides are well-known compounds in Rhamnaceae and Sterculiaceae. Their presence in Malvaceae (in APG2 sensus) suggests a possible chemical link between the ex-Tiliaceae and the Malvaceae.

A new isoflavone, 5,7-dihydroxy-4'-methoxy-3'-(2,3-dihydroxy-3-methylbutyl)isoflavone (1) was isolated from the stem bark of Ficus nymphaefolia Mill. (Moraceae) together with eight known isoflavones: genistein, erycibenin A, cajanin, 5,7,2'-trihydroxy-4'-methoxyisoflavone, erythrinin C, alpinumisoflavone, derrone and 3'-(3-methylbut-2-enyl)biochanin A. Their structures were established by spectral analysis including 1D and 2D NMR experiments.

International audience; Bioguided fractionation of the roots of Citrus sinensis (Rutaceae) led to the isolation and identification of five coumarins, namely, clausarin, suberosin, poncitrin, xanthyletin and thamnosmonin, seven acridones, namely, acrimarine B, 2-methoxycitpressine I, citpressine I, buntanine, acrimarine E, honyumine and acrimarine C, and one terpenoid, namely, limonin. Among these compounds, clausarin, 2-methoxycitpressine I and acrimarine E inhibited P-glycoprotein-mediated drug efflux in K562/R7 human leukemic cells over-expressing P-glycoprotein.Bioguided fractionation of the roots of Citrus sinensis (Rutaceae) led to the isolation and identification of five coumarins, namely, clausarin, suberosin, poncitrin, xanthyletin and thamnosmonin, seven acridones, namely, acrimarine B, 2-methoxycitpressine I, citpressine I, buntanine, acrimarine E, honyumine and acrimarine C, and one terpenoid, namely, limonin. Among these compounds, clausarin, 2-methoxycitpressine I and acrimarine E inhibited P-glycoprotein-mediated drug efflux in K562/R7 human leukemic cells over-expressing P-glycoprotein.

The first regioselective syntheses of 6-(1,1-dimethylallyl)- and 8-(3,3-dimethylallyl) chrysins have been designed. Claisen rearrangement of protected 5- O -(3,3-dimethylallyl) chrysin in N , N -diethylaniline at 200–217°C gave selective access to the 8-(3,3-dimethylallyl) isomer. Similar rearrangement in N , N -diethylbutylamine at 140–160°C, or in cycloheptane/Eu(fod) 3 at 100°C, led to the formation of the 6-(1,1-dimethylallyl) isomer. Four different protecting groups for position 7 of chrysin have been compared, and found to follow the order of interest Bz>MOM>TBDPS>MEM.

Regioselective control of the Claisen rearrangement of 7-MEM-5-prenyl chrysin was achieved by microwave irradiation. The nature of the products was influenced by the irradiation power and the type of solvent. Irradiation at 750 W in N,N-diethylaniline specifically yielded the 8-(3,3-dimethylallyl) para-rearranged product while refluxing in N,N-diethylbutylamine gave selective access to the 6-(1,1-dimethylallyl) ortho-rearranged compound.

A benzophenone glycoside has been isolated from Davallia solida. Its structure was elucidated by chemical and spectral means as 4-O-beta-D-glucopyranosyl-2,6,4'-trihydroxybenzophenone. It bound with moderate affinity to the purified C-terminal cytosolic domain of P-glycoprotein, but the binding affinity was 6- to 10-fold increased for its aglycone derivative and other related benzophenones.A benzophenone glycoside has been isolated from Davallia solida. Its structure was elucidated by chemical and spectral means as 4-O-beta-D-glucopyranosyl-2,6,4'-trihydroxybenzophenone. It bound with moderate affinity to the purified C-terminal cytosolic domain of P-glycoprotein, but the binding affinity was 6- to 10-fold increased for its aglycone derivative and other related benzophenones.

Analytical capillary zone electrophoresis (CZE) conditions including concentration, pH value and nature (complexing or non-complexing) of the running buffer with or without the addition of methanol, capillary temperature and applied voltage, were studied in order to optimize the separation and resolution of a mixture of 13 C-glycosylflavones and one flavone O-glucoside. Factors primarily responsible for differences in electrophoretic mobility of flavone C-glycosides are identical to those defined from the separation of flavonoid O-glycosides, i.e. number and position of the free hydroxy groups on the flavone skeleton, and number and type of attached sugar groups. Nevertheless, an increase in the pH value from 9 to 10 of the borate running buffer affects the elution order: such an increase induces greater relative electrophoretic mobilities of C-glycoside derivatives with a free hydroxy group at C-4′ compared with those of luteolin C-glycoside derivatives. This change in the migration order could be explained both by a decrease of the net charge linked to an increase and stability of the borate–luteolin complexation and by an increase in molecular size. Moreover the 6-C-glycosylflavones present electrophoretic mobilities lower than their homologous 8-C-glucosyl isomers. Finally, the study of C-glucosylflavones from 18 different samples of Passiflora incarnata by CZE shows a great variability in the qualitative composition. Copyright © 2000 John Wiley & Sons, Ltd.

External lipophilic methylated flavonoids have been extracted from dried leaves of Mentha aquatica, M. spicata, M. x piperita and M. citrata. After separation and purification, twenty flavonoids have been identified by means of spectrometric methods (UV, EIMS, 1H NMR). The flavonoid patterns of these species and hybrid support the view that M. x piperita may be a hybrid of M. aquatica and M. spicata while a linalool-producing sample of M. citrata may be considered a variety of M. aquatica. Cytological data agree with the observed biochemical results.

Different steps of monoterpene metabolism—disappearance of limonene, accumulation of 1,8-cineole, reduction of menthone to menthol and acetylation of menthol—have been studied in different parts of Mentha × piperita leaves of different ages. The analyses of different samples (leaf strips, disks and individual peltate trichomes, translucent or containing crystals from either epidermis) show that all these dynamic changes start at the distal extremity of the leaf and shift progressively towards the base. Except for the peltate trichomes localized within the leaf area, in which a metabolic step is being realized, the trichomes of other parts present a homogeneous monoterpene composition. The measurements of amounts of chlorophyll in two parts, distal and basal, of youngest leaves of terminal buds show that chlorophyll biosynthesis starts also at the distal extremity of the leaf. The regulation of the menthone reduction is discussed.

From the aerial part of Thymus hirtus, eight flavonoids were extracted. Besides three common flavones, apigenin, luteolin and diosmetin, three derivatives of these flavones and two derivatives of quercetin and kaempferol, substituted by a p-hydroxybenzyl moiety, were isolated. The 8-C-substitution of apigenin, luteolin, diosmetin and quercetin was demonstrated by spectrometric data.

A qualitative study of free aglycones from one clone of Mentha × piperita growing natura carried out weekly for 2 months shows that the flavonoid pattern of the whole plant remained invariable. Moreover, the flavonoid composition of mint clones possessing different terpenoid patterns have been studied. A Principal Component Analysis recognizes three flavonoid groups which correspond to the three terpenoid groups. The study of the effects of photoperiodic treatments shows that the flavonoid pattern is affected by the day length.

International audience; In our continual course toward the valorization of traditionally used endemic flora through the analysis of its chemobiodiversity, the phytochemical analysis of aerial parts of Marrubium deserti de Noé was undertaken. Dichloromethane and methanol extracts led to the isolation of terpenoid derivatives among which two were new labdane diterpenes named marrulibacetal A and desertine, respectively. Six of them were known compounds (a mixture of the isomers cyllenin A and 15-epi-cyllenin A, marrubiin, marrulactone, marrulibacetal and β-stigmasterol) and seven known phenolic compounds were also isolated: apigenin and several 7-O-substituted derivatives (apigenin-7-O-β-neohesperidoside, apigenin-7-O-glucoside, terniflorin and apigenin-7-O-glucuronide) together with two phenylethanoid glucosides (acteoside and forsythoside B). The structures and relative configurations of the new compounds were elucidated by MS and a series of 1D and 2D NMR analyses. Some pure compounds have been evaluated for their antioxidant activities through different methods: DPPH and ABTS assays as well as CUPRAC assay. Genotoxic and antigenotoxic activities of extracts and pure compounds were also evaluated in vitro on Escherichia coli PQ37 cells by the SOS Chromotest. Some of the isolated compounds like phenylethanoid derivatives showed stronger antioxidant capacity than trolox and were also able to significantly inhibit β-galactosidase induction caused by the mutagen agent nitrofurantoin.

International audience; Known for its medicinal, aromatic or culinary properties, the Lamiaceae family represents a major economic interest, in particular as a source of essential oils. The purpose of this research concerns the phytochemical and the biological study of one of the Algerian flora's medicinal plants known as Marrubium deserti de Noé. The extraction by solvents of increasing polarity: dichloromethane, ethyl acetate and butanol led to the isolation and identification of a novel labdane-type diterpene, a flavonoid and phenylpropanoid glycosides. Extracts and pure compounds were tested as antioxidant, antibacterial as well as antigenotoxic.; Connue pour ses propriétés médicinales, aromatiques ou culinaires, la famille des Lamiacées présente un intérêt économique majeur, notamment comme source d'huiles essentielles. Dans le cadre de l'étude de la biodiversité de la flore algérienne, l'analyse phytochimique et la recherche des activités biologiques des parties aériennes de Marrubium deserti de Noé ont été entreprises. L'extraction par des solvants de polarité croissante tels que le dichlorométhane, l'acétate d'éthyle et le butanol, puis la purification des extraits obtenus ont permis d'isoler et d'identifier à ce jour un diterpène original de type labdane, un flavonoïde et des phénylpropanoïdes glycosylés. Les extraits et les composés isolés ont fait l'objet d'une étude biologique comme antioxydants, antibactériens et antigénotoxiques.

From Mentha x piperita leaves, 16 free lipophilic flavonoid aglycones were isolated and identified. The variation of this flavonoid composition studied by the means of HPLC techniques from the youngest to the oldest leaves shows that the A- and B-ring O-methylation patterns of leaf pairs differ according to leaf age and would indicate the sequential activity of 4′-O- and 6-O-methyl-transferases.

Dimethylallyl (DMA) derivatives of a naturally occurring xanthone (decussatin 1) were prepared. Their activity as potential P-glycoprotein inhibitors was monitored by affinity of direct binding and compared to that of corresponding DMA-flavones. Both classes of compounds exhibited the same structure-activity relationships. Decreasing polarity enhanced the binding affinity for the P-glycoprotein C-terminal cytosolic domain since DMA derivatives were more active, but unsubstituted hydroxyl group close to the carbonyl was required for efficient activity.Dimethylallyl (DMA) derivatives of a naturally occurring xanthone (decussatin 1) were prepared. Their activity as potential P-glycoprotein inhibitors was monitored by affinity of direct binding and compared to that of corresponding DMA-flavones. Both classes of compounds exhibited the same structure-activity relationships. Decreasing polarity enhanced the binding affinity for the P-glycoprotein C-terminal cytosolic domain since DMA derivatives were more active, but unsubstituted hydroxyl group close to the carbonyl was required for efficient activity.

International audience; Four new xanthones, butyraxanthones A?D (1?4), were isolated from the stem bark of Pentadesma butyracea, together with six known xanthones (5?10) and a triterpenoid (lupeol). The structures of 1?4 were established by spectroscopic methods. Compounds 1?10 were tested in vitro for antiplasmodial activity against a Plasmodium falciparum chloroquine-resistant strain and for cytotoxicity against a human breast cancer cell line (MCF-7). Nearly all of these xanthones exhibited good antiplasmodial activity, and some of them also demonstrated potent cytotoxicity. Four new xanthones, butyraxanthones A?D (1?4), were isolated from the stem bark of Pentadesma butyracea, together with six known xanthones (5?10) and a triterpenoid (lupeol). The structures of 1?4 were established by spectroscopic methods. Compounds 1?10 were tested in vitro for antiplasmodial activity against a Plasmodium falciparum chloroquine-resistant strain and for cytotoxicity against a human breast cancer cell line (MCF-7). Nearly all of these xanthones exhibited good antiplasmodial activity, and some of them also demonstrated potent cytotoxicity.

International audience; Bio-guided fractionation of the roots of Paris polyphylla (Trilliaceae), based on inhibition of P-glycoprotein-mediated daunorubicin efflux in K562/R7 cell line, led to isolation and identification of the three saponins 3-O-Rha(12)[Ara(14)]Glc-pennogenine, gracillin and polyphyllin D, and the two ecdysteroids 20-hydroxyecdysone and pinnatasterone. These compounds were tested for multidrug reversion on P-glycoprotein (ABCB1) with both drug-selected and transfected cell lines, and also on Breast Cancer Resistance Protein (BCRP/ABCG2). By contrast to a weak efficiency on BCRP, the three saponins displayed significant effects as inhibitors of P-glycoprotein-mediated drug efflux.

From the dichloromethane extract of aerial parts of Ferula vesceritensis (Apiaceae), 11 sesquiterpene derivatives were isolated. Among them five were compounds designated as 10-hydroxylancerodiol-6-anisate, 2,10-diacetyl-8-hydroxyferutriol-6-anisate, 10-hydroxylancerodiol-6-benzoate, vesceritenone and epoxy-vesceritenol. The six known compounds were identified as feselol, farnesiferol A, lapidol, 2-acetyl-jaeschkeanadiol-6-anisate, lasidiol-10-anisate and 10-oxo-jaesckeanadiol-6-anisate. All the structures were determined by extensive spectroscopic studies including 1D and 2D NMR experiments and mass spectroscopy analysis. Two of the compounds, the sesquiterpene coumarins farnesiferol A and feselol, bound to the model recombinant nucleotide-binding site of an MDR-like efflux pump from the enteropathogenic protozoan Cryptosporidium parvum.

International audience

The monoterpene composition of leaves of Mentha x piperita has been studied by direct analyses of samples (Desorption-Concentration-Introduction Technique). Kinetic studies on individual pairs of leaves from plants subjected to different photoperiodic treatments (long or short photoperiod followed or not by an inversion of the initial photoperiod) show that the photoperiod received by the young leaves directly influenced the oil composition. Therefore the photoperiod as such is responsible for the variations of the monoterpene metabolic pathway. This conclusion is based on the likelihood that the reducing pathway (menthone-menthol) was developed in young leaves on condition that they are subjected to a long photoperiodic treatment and that the metabolic pathway originally induced by the daylength in the oldest leaves was not changed by the inversion of the initial photoperiodic treatment.

A library of 42 natural and synthetic flavonoids has been screened for their effect on cell proliferation and apoptosis in a human colonic cell line (HT-29). Examples of different classes of flavonoids have been screened, and the effects of hydroxylation, methoxylation and/or C-alkylation at various positions in the A- and B-rings have been assessed. Flavones and flavonols possess greater antiproliferative activity than chalcones and flavanones. With respect to structural modification of flavonoids, C-isoprenylation was by far the most effective, with substitution at the 8-position and longer chains, such as geranyl giving the best results. Finally, most compounds that significantly reduced cell survival also increased caspase activity, suggesting that at least part of their antiproliferative activity might be attributable to an apoptotic response.

Two new flavonol glycosides: 4′-methylquercetagetin 7-O-(6″-E- caffeoyl-β- d -glucoside ) and quercetagetin 7-O-(6- acetyl-β- d -glucoside ) along with the 7- O -glucosides of 6-hydroxykaempferol, quercetin and quercetagetin have been isolated and characterized from the leaves of Eupatorium glandulosum .

In Mentha x piperita leaves, the peltate glands may be divided into two types according to the presence or the absence of crystals in the head of the trichomes. In both types, the free lipophilic flavonoid aglycones, characterized by UV and chromatographic data, are located in the head of the peltate glands, together with monoterpenes.

Phytochemical investigation of the leaves of Umbilicus pendulinus afforded in addition to 2-O-caffeoyl malate, isoquercitrin and Z-venusol, the new isomer E-venusol. Special NMR experiments were carried out to elucidate the configuration of the two latter compounds.

Previous studies have shown that flavones bind to P-glycoprotein (Pgp) with higher affinity than isoflavones, flavanones, and glycosylated derivatives. In the present work, a series of C- or O-substituted hydrophobic derivatives of chrysin were synthesized to further investigate structural requirements of the A ring toward Pgp modulation. Increasing hydrophobicity at either position 6, 8, or 7 increased the affinity of in vitro binding to a purified cytosolic domain of Pgp, but only benzyl and 3,3-dimethylallyl C-substitution produced a high maximal quenching of the protein intrinsic fluorescence. Inhibition of membrane Pgp within leukemic cells, characterized by intracellular drug accumulation, was specifically produced by isoprenylated derivatives, with 8-(3,3-dimethylallyl)chrysin being even more efficient than the commonly used cyclosporin A.

Dimethylallyl (DMA) derivatives of a naturally occurring xanthone (decussatin 1) were prepared. Their activity as potential P-glycoprotein inhibitors was monitored by affinity of direct binding and compared to that of corresponding DMA-flavones. Both classes of compounds exhibited the same structure-activity relationships. Decreasing polarity enhanced the binding affinity for the P-glycoprotein C-terminal cytosolic domain since DMA derivatives were more active, but unsubstituted hydroxyl group close to the carbonyl was required for efficient activity.

The genus Ammoides (Apiaceae) tribe of Ammineae includes two species in Algeria, one of which is endemic: Ammoides atlantica (Coss. et Dur.) Wolf; the other one, Ammoides pusilla (Brot.) Breistr, is widespread in the Mediterranean region [1]. The aerial parts of Ammoides atlantica were collected from Megress Mountain (Eastern Algeria) at 1500 m above sea level during June 2004 and identified by Dr. H. Laouer. A voucher specimen (B6308) has been deposited in the Museum d’Histoire Naturelle of Nice (France). The air-dried powdered parts (700 g) of A. atlantica were macerated three times in boiling methanolic solution (70%). The MeOH extract was concentrated to dryness, the residue was dissolved in boiling water (600 mL) after filtration, and the residue was extracted successively three times with AcOEt and n-butanol (3×200 mL) to give 2.5 and 22.7 g of the respective residues. Solvents were evaporated and the residues of n-BuOH and AcOEt extracts were dissolved in small volumes of MeOH. Analysis by two-dimensional paper chromatography using 15% AcOH and BAW (n-BuOH–AcOH–H2O, 4:1:5, upper phase) as solvents indicated that extracts of n-BuOH and AcOEt contain identical separation of flavonoids. The AcOEt extract was applied to a column of silica gel and eluted with a gradient of n-hexane–AcOEt–MeOH with increasing polarity to obtain nine fractions (A-I). Concentration under reduced pressure of fractions B, D, and G gave three precipitates, which were filtered and washed with MeOH to obtain three compounds 1 (10 mg), 2 (32 mg), and 3 (40 mg). Fraction C was purified by preparative TLC on silica gel eluted with n-hexane–AcOEt (2:8) to afford compound 4 (10 mg). Final purification of each compound for spectral analysis was carried out using MeOH over Sephadex LH-20 (Pharmacia Fine Chemicals), prior to UV, MS, and 1H spectral analysis [2, 3]. Hydrolysis of the glycosides 3 and 4 (HCl 0.1 N, 2 h) yielded the sugar residues and the aglycones, all of which were chromatographed with authentic samples. 1H NMR spectra were recorded in CD3OD at 300 MHz. All the structures were in good agreement with literature data. Compound 1, C15H10O5, mp 345°C, identified as apigenin [4]. Compound 2, C15H10O6, mp 330°C, identified as luteolin [5]. Compound 3, C21H20O10, mp 220–222°C identified as apigenin 7-O-glucoside [6]. Compound 4, C21H20O11, mp 239–242°C, identified as luteolin 7-O-glucoside [7]. Only one flavonoid, luteolin 7-O-glucoside [7], has recently been reported from an Egyptian A. pusilla. Compounds 1–4 were isolated for the first time from A. atlantica, and compounds 3, 4 are reported for a second time from a Ammoides species [6, 7]. Compounds 1 and 2 are new for the genus Ammoides.

International audience; From the diethyl ether extracts of the aerial parts of Thymus herba barona, the flavanones eriodictyol,naringenin and the flavones luteolin, sorbifolin, thymusin, cirsiliol, apigenin, sideritoflavone, cirsimaritin, cirsilineol, xanthomicrol, 8-methoxycirsilineol and genkwanin were isolated and characterized. This is the first report of sorbifolin and cirsiliol in the genus Thymus. The distribution of these flavonoids in the seven terpenoid chemotypes of T. herba barona growing in Corsica was studied and the chemotaxonomic implications of this data discussed.

Three taxa have been described to study common junipers of the old world : Juniperus communis L., Juniperus alpina (Suter) Celak and Juniperus hemisphaerica Presl.. Their populations show a large variability and morphological criteria (habit and leaf morphology) do not always make it possible to differenciate between them. Proanthocyanic (prodelphinidin) analysis was performed on 450 specimens to better understand biological diversity within this complex. A multi-criteria approach (morphology, geography, ecology and biochemistry) yielded reference profiles for J, communis (23 specimens), J. alpina (18 specimens) and J. hemisphaerica (19 specimens). These types were used as guidelines for the analysis of populations found in several mountain ranges which showed, depending on the area, introgression processes (J. communis x J. alpina", J. communis x J. hemisphaerica) revealing the originality of either islands (Corsica) or some mountains that function as continental biogeographic islands (Mount Ventoux, Lure Mountain, Apennines). Creeping junipers found in Mediterranean (Sierra Nevada) and peri-Mediterranean (Pyrénées, Massif Central, Mount Ventoux, Southern Alps pro parte) mountains do not generally belong to the «nana» taxon which is restricted to the Alps and some «islands» (Corsica, Apennines). They are fundamentaly linked with the «communis» taxon (sensu stricto) as are Scandinavian and Baltic populations, whatever their habit. The very high biological diversity of Juniperus aggr. communis L. led the authors to discuss the phylogenetic origins of the main taxa and to propose a new biogeographic scheme for their distribution. Hypotheses are made concerning the ecological consequences of the studied populations’ biochemical structuration on strategies for repelling herbivores., Trois taxons ont été décrits pour réunir les genévriers communs de l’Ancien Monde : Juniperus communis L., Juniperus alpina (Suter) Celak, Juniperus hemisphaerica Presl. Leurs populations présentent une grande variabilité et les critères morphologiques (port et feuillage) ne permettent pas toujours de les séparer sans ambiguïté. Pour parvenir à une approche plus complète de la diversité biologique au sein de ce groupe, 450 spécimens ont été soumis à l’analyse proanthocyanique (prodelphinidine). Une approche multicritères (morphologique, géographique, écologique et biochimique) a tout d’abord permis de caractériser les profils référentiels de J. communis (23 spécimens), J. alpina (18 spécimens) et J. hemisphaerica (19 spécimens). Ces types ont ensuite guidé une analyse de populations présentes dans différents massifs montagneux, mettant en évidence selon les secteurs des processus d’introgression (J. communis x J. alpina ; J. communis x J. hemisphaerica ) qui expriment l’originalité des îles (Corse), ou de certains massifs fonctionnant comme des îles biogéographiques continentales (Ventoux, Lure, Apennins). Plus généralement, les genévriers rampants des montagnes méditerranéennes (Sierra Nevada) et péri-méditerranéennes (Pyrénées, Massif Central, Mont Ventoux, Alpes du Sud pro parte ) ne relèvent pas du taxon «nana», restreint aux Alpes et à quelques «îles» (Corse, Apennins) ; ils sont à rattacher fondamentalement au taxon communis (sensu stricto), comme d’ailleurs les populations Scandinaves et baltes, quel qu’en soit le port. La diversité biologique très marquée de Juniperus aggr. communis L. conduit les auteurs à discuter des origines phylogénétiques des principaux taxons, et à construire un nouveau schéma biogéographique de leur répartition. Des hypothèses sont formulées quant aux conséquences écologiques de la structuration biochimique des populations étudiées sur les tactiques de dissuasion des herbivores., Barbero Marcel, Bayet Christine, Hammoud Abdulillah, Laracine-Pittet Claire, Lebreton Philippe. Diversité biologique du Genévrier commun, espèce collective flavoniquement polymorphe. In: Ecologia mediterranea, tome 16,1990. pp. 13-39.

A new flavonol glycoside isolated from the leaves of Eupatorium glandulosum has been characterized as 6-hydroxykaempferol 7-(6″-caffeoylglucoside) by chemical and spectral methods.

Phytochemical investigation of the leaves of Umbilicus pendulinus afforded in addition to 2-O-caffeoyl malate, isoquercitrin and Z-venusol, the new isomer E-venusol. Special NMR experiments were carried out to elucidate the configuration of the two latter compounds.