Louisette Le Men-Olivier

Structure-Activity Relationships of Haemolytic Saponins

The haemolytic activity of 59 samples, natural or partially synthetic pure saponins and mixtures thereof, was determined. The tested saponins possessed triterpenic genins and six structural skeleton types were studied. Structure-activity relationships were established by comparison of the functional groups of each saponin and of the branched sugar chains attached to aglycone. The haemolytic activity is shown to depend on the number of sugar units in the chains, as well as on the presence of an osidic chain in position 3 or of functional groups on the genin such as carboxylic or 16a-OH. Comparison of activities of monodesmosidic and bidesmosidic saponins showed that monodesmosidic saponins were generally more active and suggested a polar balance between the two sugar chains at positions 3 and 28. Twelve saponins showed strong haemolytic activity and five possessed a Haemolytic Index (HI) greater than 100,000, such as the a- and ß-aescines (HI: 200,000).

Isolation of indole alkaloids from Catharanthus roseus by centrifugal partition chromatography in the pH-zone refining mode

Centrifugal partition chromatography (CPC) in the pH-zone refining mode allowed a preparative and efficient isolation of vindoline, vindolinine, catharanthine and vincaleukoblastine from a crude mixture of Catharanthus roseus alkaloids. The separation protocol was tested with a synthetic mixture of vindoline, catharanthine and vincaleukoblastine. The fraction content was analyzed and the results compared with theoretical chromatograms obtained by numerical simulation. The increase in injected sample mass results in an improvement of the purity of the isolated compounds. This observation, confirmed by theory, is of prime importance for the development of preparative pH-zone refining CPC as a preparative separation method.

Bioactive phenolic glycosides from Amburana cearensis

Abstract Coumarin ( 1 ) and two new phenolic glycosides have been isolated from the stem bark of Amburana cearensis , a tree reported in the Chacobo pharmacopoeia to be used against fever-causing diseases. The novel compounds were identified as: 4-(O-β- d -glucopyranosyl)-hydroxy-7-(3′,4′-dihydroxy-benzoyl)-benzyl alcohol ( 2 ) and 4-(O-β- d -glucopyranosyl)-hydroxy-7-(3′-methoxy-,4′-hydroxy-benzoyl)-benzyl alcohol ( 3 ). All three compounds were assayed in vitro for antimalarial, antiprotozoal, antifungal and antibacterial activities.

Alstonia species: are they effective in malaria treatment?

A review of the literature on Alstonia species indicates that evidence in support of their effectiveness in the treatment of malaria is controversial. The antiprotozoal activity of the major alkaloid present in Alstonia species, echitamine, was assessed in vitro against Plasmodium falciparum and Giardia intestinalis. Echitamine displayed little antiplasmodial activity, but two quinoline alkaloids from A. coriacea (corialstonine and corialstonidine) were found to have some activity against P. falciparum although this was approximately 10 times less than that of quinine. None of the three Alstonia alkaloids was active against G. intestinalis. These results are discussed in the context of previously published data.

Preparative separation of anthocyanins by gradient elution centrifugal partition chromatography

Abstract Centrifugal partition chromatography (CPC) allowed purification of anthocyaanins from Champagne vintage by-products (Vitis vinifera) and from blackcurrant (Ribes ni9grum L.). In the first case a 5-1 pilot-CPC used on a preparative multi-gram scale. The biphasic solvent system used was ethyl acetate-1-butanol-water, acidified by TFA (pH 1–3) for both gradient and isocratic normal-phase elutions. Separation selectives which differ for cyanidin and delphinidin glycosides in CPC and cellulose-TLC using the solvent system 1-butanol-acetic acid-water (4:1:5) are discussed.

Dammarane saponins from Zizyphus lotus

Four dammarane-type saponins were isolated by means of centrifugal partition chromatography from the root bark of Zizyphus lotus. Their structures were elucidated using a combination of 1D and 2D 1H and 13C NMR spectra and mass spectroscopy. One of these glycosides is the known jujuboside A. The others are three new dammarane saponins, identified as 3-O-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl (1-->3)-[alpha-L-rhamnopyranosyl(1-->2)]-alpha-L-arabinopyranosyl jujubogenin = jujuboside C, 3-O-alpha-L-rhamnopyranosyl (1-->2)-[beta-D-glucopyranosyl(1-->3)]-beta-D-galactopyranosyl lotogenin = lotoside I, and 3-O-alpha-L-rhamnopyranosyl(1-->2)-[beta-D-glucopyranosyl (1-->3)]-beta-D-glucopyranosyl lotogenin = lotoside II. Lotogenin is a new dammarane derivative identified as (15R, 16R, 20R, 22R)-16 beta, 22-epoxydammar-24-ene-3 beta, 15 alpha, 16 alpha, 20 beta-tetraol.

Alkaloids from stem bark and leaves of Peschiera buchtieni

Abstract During an investigation of the stem bark and leaves of Peschiera buchtieni , 34 alkaloids were isolated. Eight new alkaloids were obtained from the stem bark, N -methyl-pericyclivine, 18,19( R )-dihydroxycoronaridine, chloromethylene affinisinium, demethylaccedinisine, 18-hydroxyaffinisine, buchtienine, 3-hydroxytetrahydroolivacine and demethylceridimine. The known alkaloids from the stem bark were coronaridine, voaphylline, coronaridine hydroxyindolenine, heyneanine, eglandine, eglandulosine, 19-epi-heyneanine, voachalotine, ochropamine, olivacine, ibogamine, affinisine, N -oxyaffinisine, vallesamine, ( E )-isositsirikine, voaphylline hydroxyindolenine, normacusine B, janetine, 3,14-dihydroolivacine, 3′( R / S )-hydroxy- N -demethyl-tabernamine, 4′,17β-dihydrotchibangensine, ceridimine and N -demethyltabernamine. Apodine, voacristine, voacristine hydroxyindolenine and olivacine were identified in leaves.

Saponins from Steganotaenia araliacea.

Six saponins have been isolated and identified from the leaves of Steganotaenia araliacea. They were identified as 3-O-[beta-D-galactopyranosyl(1----2)-(beta-D-galactopyranosyl (1----3))-beta-D-glucuronopyranosyl]-21-O-tigloyl and -21-O-angeloyl-R1-barrigenol, 3-O-[beta-D-glucopyranosyl(1----2)-(beta-D-xylopyranosyl (1----3))-beta-D-glucuronopyranosyl]-21-O-tigloyl and -21-O-angeloyl-R1-barrigenol, 3-O-[beta-D-glucopyranosyl(1----2)-(beta-D-glucopyranosyl-(1----3))-(alp ha-L- rhamnopyranosyl(1----4))-beta-D-glucopyranosyl] steganogenin and 3-O-[(beta-D-galactopyranosyl(1----2)-beta-D-glucuronopyranosyl]-2 8-O- beta-D-glucopyranosyl olean-12-ene-28-oic acid. Steganogenin is a new 17,22-seco-oleanolic acid derivative. The structures of the saponins were established by analysis of their 1H and 13C NMR spectra with the help of 2D-experiments and by Californium Plasma Desorption Mass Spectrometry.

Further alkaloids from strychnos longicaudata and strychnos ngouniensis

Abstract Twenty four alkaloids have been isolated and identified from the root and stem barks of Strychnos longicaudata Gilg and Strychnos ngouniensis Pellegrin. Among these, 17 alkaloids are isolated for the first time; the novel bisindole series represented by longicaudatine includes now two other compounds: longicaudatines F and Y; besides ngouniensine, its epimer epingouniensine has been isolated along with two glucosyl-ngouniensines. Other new alkaloids include tubotaiwinal and several bases possessing the akuammicine skeleton.

Alkaloids of Strychnos johnsonii

Abstract Twenty-three alkaloids have been identified in the root bark and stem bark of Strychnos johnsonii from Zaire. They are demethoxycarbonyl-3,14-dihydro-gambirtannine, angustine, dihydro-cycloakagerine, O -ethylakagerine, O -ethylakagerine lactone, dihydro decussine, normalindine, oxojanussine, tetrahydroalstonial, ajmalicinial, norepimalindine, norharman, harman, akagerine, akagerine lactone, janussines A and B, tetrahydro akagerine, demethoxycarbonyl-3,14,15,16,17,18-hexahydro-gambirtannine, dihydrocorynantheol, anthirine lactone, anthirine and isoanthirine.