Saponins from Verbascum nigrum.

Two triterpene saponins have been isolated from the inflorescences of Verbascum nigrum. Their structures were determined by chemical and spectral methods as 3-O-([alpha-L-rhamnosyl-(1-->4)-(beta-D-glucopyranosyl-(1-->3)]-be ta-D-glucopyranosyl]-(1-->2)-beta-fucopyranosyl)-13 beta,28-epoxyolean-11-ene-3 beta,23-diol and 3-O-([alpha-L-rhamnosyl-(1-->4)-(beta-D-glucopyranosyl-(1-->3)-bet a-D- glucopyranosyl]-(1-->2)-beta-fucopyranosyl)-11-methoxy-olean-12-en e-3 beta,23,28-triol.

Saponins from Harpullia cupanioides.

Five new saponins have been isolated from the stem bark of Harpullia cupanioides and identified as 3-O-beta-D-glucopyranosyl(1-->2)[alpha-L-rhamnopyranosyl(1-->3)] beta-D-glucuronopyranosyl 22-O-angeloyl-A1-barrigenol, 3-O-beta-D-glucopyranosyl(1-->2)[alpha-L-rhamnopyranosyl(1-->3)] beta-D-glucuronopyranosyl 28-O-angeloyl-A1-barrigenol, 3-O-beta-D-galactopyranosyl(1-->2)[alpha-L-rhamnopyranosyl(1-->3)] beta-D-glucuronopyranosyl 28-O-angeloyl-A1-barrigenol. 3-O-beta-D-galactopyranosyl(1-->2)[alpha-L-rhamnopyranosyl(1-->3)] beta-D-glucuronopyranosyl 16-O-beta, beta-dimethylacryloyl-camelliagenin A and 3-O-beta-D-glucopyranosyl(1-->2)[alpha-L-rhamnopyranosyl(1-->3)] beta-D-glucuronopyranosyl 28-O-angeloyl-camelliagenin A. The structures were elucidated by analysis of 2D-NMR spectra and mass spectra.

Cytotoxic polyisoprenes and glycosides of long-chain fatty alcohols from Dimocarpus fumatus.

The ethanolic extract from the stem bark of Dimocarpus fumatus, showed in vitro cytotoxic activity against KB cells. Fractionation of the extract gave compounds belonging to different classes. The two major components have been identified as a benzoquinone, sargaquinone, and a chromene, sargaol. One sphingolipid, soyacerebroside I, two glycosides of sitosterol, and fatty acids were also identified. Besides these known compounds, two new glycosides of long-chain fatty alcohols have been identified as 1-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D- glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->6)-beta-D- glucopyranosyl]hexadecanol and 1-O-[[alpha-L-arabinopyranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1 -->2)- beta-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->6)-beta-D- glucopyranosyl] hexadecanol, and a mixture of three new diacylglycerylglucosides has been isolated. These structures were elucidated by analysis of 2D-NMR and mass spectra.

Saponins from three species of Mimusops.

Six saponins were isolated from the seed kernel of Mimusops elengi, M. hexandra and M. manilkara. Their structures were determined using a combination of 1H NMR, 13C NMR and mass spectroscopy. Three of them are new compounds: 3-O-(beta-D-glucuronopyranosyl) 28-O-(alpha-L-rhamnopyranosyl (1-->3) beta-D-xylopyranosyl(1-->4) [alpha-L-rhamnopyranosyl(1-->3)] alpha-L-rhamnopyranosyl(1-->2) alpha-L-arabinopyranosyl) protobassic acid, 3-O-(beta-D-glucuronopyranosly) 28-O-(alpha-L-rhamnopyranosyl(1-->3) beta-D-xylopyranosyl(1-->4) alpha-L-rhamnopyranosyl(1-->2) alpha-L-arabinopyranosyl) 16-alpha-hydroxyprotobassic acid and 3-O-(beta-D-glucopyranosyl(1-->3) beta-D-glucopyranosyl) 28-O-(alpha-L-rhamnopyranosyl(1-->3) beta-D-xylopyranosyl(1-->4) alpha-L-rhamnopyranosyl(1-->2) alpha-L-arabinopyranosyl) protobassic acid.

Triterpene saponins from Myrsine pellucida.

Quercitol, five saponins and 3-O-(6'-O-palmitoyl) beta-D-glucopyranosyl stigmasterol were isolated from the stem bark of Myrisine pellucida. These compounds are described for the first time in this plant and their structures were determined using a combination of 1H and 13C NMR, and mass spectroscopy. The two saponins are new compounds, 3-O-(alpha-L-rhamnopyranosyl (1-->2) beta-D-glucopyranosyl (1-->4) alpha-L-arabinopyranosyl) cyclamiretin A and 3-O-(beta-D-xylopyranosyl) (1-->2) beta-D-glucopyranosyl (1-->4) [beta-D-glucopyranosyl (1-->2)] alpha-L-arabinopyranosyl) cyclamiretin D.

4-Quinolinone alkaloids from Dictyoloma peruviana.

The stem-bark of Dictyoloma peruviana yielded two new piperidino [1,2-a] 4-quinolinones, dictyolomide A and dictyolomide B. Their structures were established by NMR spectroscopy.

Saponins from Pisonia umbellifera.

Six saponins were isolated from the leaves of Pisonia umbellifera. Three are new oleanolic acid saponins, and two of them contain an unusual seco-glycopyranosyl moiety. Their structures were determined using a combination of 1H and 13C NMR, and mass spectrometry as 3-O-{beta-D-glucopyranosyl(1-->2)[beta-D-glucopyranosyl (1-->2)-beta-D-xylopyranosyl(1-->3)]-beta-D-glucuronopyranosyl} 28-O-beta-D-glucopyranosyl olean-12-en-3 beta-ol-28-oic acid, 3-O-{2'-(2"-O-glycolyl)-glyoxylyl-beta-D-glucuronopyranos yl} 28-O-beta-D-glucopyranosyl olean-12-en-3 beta-ol-28-oic acid and 3-O-{2'-O-glycolyl)-glyoxylyl-beta-D-glucuronopyranosyl++ +} olean-12-en-3 beta-ol-28-oic acid.

Withanolide glycosides from Dunalia australis.

Four new withanolide glycosides, (20R,22R)-O-(3)-[beta-D- xylopyranosyl(1----3), beta-D-xylopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide, (20R,22R)-O-(3)-[beta-D-xylopyranosyl(1----3), beta-D-glucopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide, (20R,22R)-O-(3)-[beta-D- glucopyranosyl(1----3), beta-D-glucopyranosyl(1----4)]-beta-D-glucopyranosyl- 3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide and (20R,22R)-O-(3)-[beta-D-glucopyranosyl(1----3), beta-D- glucopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta, 12 beta,20-trihydroxy- 1 alpha,acetoxy-witha-5,24-dienolide, named dunawithanines C, D, E and F, respectively, were isolated from Dunalia australis. Their structures were elucidated on the basis of spectral and chemical evidence, especially NMR data of the peracetates.

Triterpene saponins from Verbascum songaricum.

Songarosaponin A, B and C isolated from the aerial parts of Verbascum songaricum were shown to be 3-O-[alpha-L-rhamnopyranosyl-(1----4)-beta-D-glucopyranosyl-(1----3)]-[b eta-D-glucopyranosyl-(1----2)-beta-D-fucopyranosyl]-olea-11,13-die ne-3 beta-23,28-triol, 3-0-[alpha-L-rhamnopyranosyl-(1----4)-beta-D-glucopyranosyl-(1----3)]-[b eta-D-glucopyranosyl-(1----2)]-beta-D-fucopyranosyl]-olea-1 1-ene-3 beta-13,23,28-tetrol and 3-O-[beta-D-glucopyranosyl-(1----4)]-[beta-D-glucopyranosyl-(1----3)]-[b eta-D-glucopyranosyl-(1----2)]-beta-D-fucopyranosyl]-13 beta,28-epoxyolea-11-ene-3 beta,23-diol.

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.

Seco-glycosides of oleanolic acid from Beta vulgaris.

Two new oleanolic acid saponins were isolated from the leaves and roots of Beta vulgaris. Both contained the unusual feature of a 3,4 seco-glycopyranosyl moiety. Their structures were established by a combination of 2D NMR experiments and of Californium plasma desorption mass spectrometry.

Saponins from the stem bark of Filicium decipiens.

Four new saponins have been isolated from the stem bark of Filicium decipiens and identified as 3-O-{beta-D-glucopyranosyl(1-->2)-beta- D-glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)-beta- D-xylopyranosyl (1-->6)]. [4-O-angeloyloxy-alpha-L-arabinopyranosyl(1-->2)-alpha-L- rhamnopyranosyl(1-->2)]}-beta-D-glucopyranosyl gypsogenic acid, 3-O-{beta-D-glucopyranosyl(1-->2)-beta-D- glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)- beta-D-xylopyranosyl(1-->6)] [4-O-angeloyloxy-alpha-L- arabinopyranosyl(1-->2)-alpha-L-rhamnopyranosyl(1-->2)]}-beta-D- glucopyranosyl medicagenic acid, 3-O-{beta-D-glucopyranosyl(1-->2)-beta-D- glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)] [beta-D-xylopyranosyl(1-->4)]alpha-L-rhamnopyranosyl(1-->2)-4-O-[3'- hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyroyloxy++ +]-beta-D- fucopyranosyl} medicagenic acid and 3-O-beta-D-glucopyranosyl-28-O- {[alpha-L-arabinopyranosyl(1-->2)] [beta-D-xylopyranosyl(1-->4)] alpha-L-rhamnopyranosyl(1-->2)-4- O-[(3'-hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyro yloxy]-beta- D-fucopyranosyl} zanhic acid. These structures were elucidated by analysis of 2D-NMR spectra and of electrospray ionization mass spectra.

Saponins from stem bark of Petersianthus macrocarpus.

Two bioactive saponins were isolated from the stem bark of Petersianthus macrocarpus. Their structures were elucidated by chemical degradations and by a combination of 2D NMR techniques and by Californium plasma desorption mass spectrometry. They are 3-O-([beta-D-galactopyranosyl (1-->2)][beta-D-galactopyranosyl (1-->3)]- beta-D-glucuronopyranosyl)-21-O-[3-(3-tigloyloxynilic acid)-4-tigloyloxy- alpha-L-arabinopyranosyl] barringtogenol C and 3-O-([beta-D-galactopyranosyl (1-->2)][beta-D-galactopyranosyl (1-->3)]-beta-D-glucuronopyranosyl)-28-O-alpha-L-rhamnopyranosyl barringtogenol C-21-O-benzoate. The absolute configuration of nilic acid was determined by partial synthesis. 3,3'-Dimethoxy ellagic acid and 3,3'-dimethoxy-4-O-beta-D- glucopyranosyl ellagic acid were also isolated.

Triterpenoid glycosides from the bark of Mimosa tenuiflora.

Two new saponins were isolated from Mimosa tenuiflora and their structures established as 3-O-[alpha-L-rhamnopyranosyl(1----2)-beta-D-glucopyranosyl-(1----3]-(alp ha-L- arabinopyranosyl-(1----4]-beta-D-xylopyranosyl-(1----2)]-[beta-D- xylopyranosyl-(1----4)]-beta-D-glucopyranosyl)-28-O-alpha-L-rhamnopyrano syl oleanolic acid and 3-O-[alpha-L-rhamnopyranosyl-(1----2)-beta-D-glucopyranosyl-(1----3]-(al pha- L-arabinopyranosyl-(1----4]beta-D-xylopyranosyl-(1----2)]-[beta-D- xylopyranosyl-(1----4)]-beta-D-glucopyranosyl) oleanolic acid.

A ferulic acid ester of sucrose and other constituents of Bhesa paniculata.

A novel derivative of sucrose, beta-(3,6-di-O-feruloyl)-fructofuranosyl-alpha-(2,3,4,6-tetra-O-ac etyl)- glucopyranoside, was isolated from the wood of Bhesa paniculata. Its structure was determined by a combination of 2D 1H-1H and 1H-13C correlation NMR spectroscopy. The known compounds, glycerol 1-9',12'-octadecadienoate, beta-sitosterol, (+/-)-pinoresinol, methyl 3,4-dihydroxybenzoate, 4-hydroxy-3-methoxybenzoic acid, anofinic acid and 2-(1'-methylethenyl)-benzofuran-5-carboxylic acid were also isolated.

Proton NMR spectroscopy assignment of D-glucose residues in highly acetylated starch.

1H NMR spectroscopy assignments have been obtained for starch acetates using COSY and HOHAHA experiments by comparison with the spectra of amylose triacetate and of peracetylated malto-oligosaccharides (maltotriose, maltotetraose, maltoheptaose). These assignments are valuable for the location and evaluation of the substitution pattern in modified starches. The bulk of the 1H NMR spectra of highly acetylated starch strongly resembles the spectrum of amylose triacetate in which all protons are identified and display distinct chemical shifts. The resolving power of the HOHAHA experiment allowed the distinction of minor spin systems. Beside these strong signals pertaining to an average 2.3.6-tri-O-acetyl-alpha-(1-->4) linked D-glucopyranose unit in an infinite chain, the combination of COSY and HOHAHA experiments allowed the identification of these systems to the terminal, n-1, n-2, and to partially acetylated glucopyranosyl units. As an example, two different preparations of starch acetates with degrees of substitution 2.74 and 2.63 were examined. In one case, NMR demonstrates that the defects of acetylation are random on the polymeric chain (with corresponding signals for unacylated secondary hydroxyl positions at delta 3.61 and 3.40) while in another case, these signals are not detectable, probably due to the presence of clusters of non-acetylated residue forming solid-like zones.

How far can one go in the field of structural elucidation of natural products?

Structural elucidation of bioactive compounds has always been and remains a field of interest for organic chemists. Tools have constantly evolved over the past fifty years and the field has become so sophisticated and relies so heavily on instruments and computers that is becoming an area for specialists. Specialization has become such that the natural product chemist now faces X-ray professionals, mass spectrometry specialists, not to speak of NMR experts; all these people use different tools, different quantities of material and it may happen that once our natural product chemists opens the door of one of their laboratories, he is not welcome in the others anymore. The purpose of this paper is to discuss briefly what can be done best with each of the tools. It will be also shown that chemistry may still find a use, especially when problems are very difficult to tackle. Examples will be chosen among terpenes, antibiotics and toxins.

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.

Julocrotine, a glutarimide alkaloid from Croton membranaceus.

The isolation and spectral data of julocrotin (1), a glutarimide alkaloid from Croton membranaceus are reported.