Alkaloids of the stem bark of Alstonia lanceolifera

Nine indole alkaloids were identified from the stem bark of Alstonia lanceolifera: (?)-lochnericine, 10,11-dimethoxy 1-methyldeacetylpicraline 3′,4′,5′-trimethoxybenzoate, 10,11-dimethoxy-1-methylpicraline, akuammiline, picraline, 10-methoxy-nor-C-fluorocurarine, 11-methoxyakuatiammicine, 10-methoxycompactinervine and 11-methoxycompactinervine.     

Alcaloides d'Alstonia lanceolifera

From the aerial parts of Alstonia lanceolifera six alkaloids were isolated and identified: O-trimethoxycinnamoylvincamajine, O-trimethoxy-cinnamoyl-10-methoxyvincamajine, O-trimethoxycinnamoyl-10-hydroxyvincamajine, O-trimethoxybenzoylhydroxyvincamajine, 10-methoxyvincamajine, N(a)-methyl-10-methoxyakuammidine. These alkaloids are new compounds, except for the first. The position of aromatic substituents was determined by study of the Nuclear Overhauser Effect (N.O.E.) in the NMR spectra.     

Alkaloids of Alstonia lanceolata

Thirteen alkaloids were isolated from the stem bark of Alstonia lanceolata. They were lochnericine, gentianine, 10,11-dimethoxy-1-methyl-deacetylpi     

Alkaloids of Alstonia plumosa

Nineteen indole alkaloids have been isolated from the root and stem barks of Alstonia plumosa, from New Caledonia. Twelve of them were known compou     

Alkaloids of Alstonia sphaerocapitata

Twenty alkaloids have been isolated from the leaves, fruit and stem-bark of Alstonia sphaerocapitata from New Caledonia. They were vincamedine, 10-methoxyvincamedine, Z-isositsirikine, akuammicine, quaternoline, 11-methoxyakuammicine, tubotaiwine, 10-methoxyvincamedine N(4)-oxide, cabucraline, cathafoline, caberoline, vincoridine, quebrachidine, quaternoxine, nor C-fluorocurarine, desoxycabufiline, nordesoxycabufiline and three alkaloids of unknown structure.     

Some alkaloids of Alstonia undulata

Sixteen indole alkaloids have been identified in the root bark and in the leaves of Alstonia undulata from New Caledonia. They are vincamedine, tetrahydroalstonine, alstonidine, deplancheine, fluorocarpamine, pleiocarpamine, 11-methoxyakuammicine, cabucraline, desoxycabufiline, cabucraline-N(4)-oxide, 11-methoxyakuammicine N(4)-oxide, gentiacraline, plumocraline, vincorine, cathafoline and pericyclivine. Five bis indoles of unknown structure have been isolated. The root bark alkaloid mixture contains gentiacraline the first alkaloid made up of an indole and a pyridine alkaloid.     

Scholarine: An indole alkaloid of Alstonia scholaris

A new alkaloid designated scholarine was isolated from the leaves of Alstonia scholaris. It was (±) 12-methoxyechitamidine as determined by chemical and spectroscopic investigations.     

Alkaloids of Hunteria zeylanica

Twenty alkaloids were isolated from the leaves and stem bark of Hunteria zeylanica, collected in Kenya. They were: 3-epi-dihydrocorymine 3-acetate, norisocorymine, corymine, 3-epi-dihydrocorymine 17-acetate, picralinal, picrinine, 3-epi-dihydrocorymine, isositsirikine, lanceomigine, geissoschizol, gentianine, kopsinine, eburnamine, norpleiomutine, pleiocarpamine, tubotaiwine, pleiomutinine, 19′-epi-pleiomutinine, yohimbol and 10-hydroxy-16-epi-affinine.     

Alcaloïdes des feuilles et écorces de tronc d'Alstonia odontophora

Six known indole alkaloids were isolated from the leaves and stem bark of Alstonia odontophora: vincamajine, 11-methoxy- akuammicine, quebrachidine, pleiocarpamine, antirhine, pleiocorine and pleiocraline, along with the novel bisindole, N (I′)-demethylpleiocorine.     

Alkaloids from Alstonia angustifolia

Six new alkaloids, viz., alstolactone, affinisine oxindole, lagumicine, N(4)-demethylalstonerine, N(4)-demethylalstonerinal, and 10-methoxycathafoline N(4)-oxide, in addition to 36 other known alkaloids, were obtained from the leaf extract of Alstonia angustifolia var. latifolia. The structures of the new alkaloids were determined using NMR and MS analysis.     

Alkaloids of Pterotaberna inconspicua

Sixteen alkaloids were isolated from the seeds and root-bark of Pterotaberna inconspicua, collected in Zaïre. They were voacangine 3-carbonitrile, voacangine, voacristine, 3,6-oxido-voacangine, vobasine, 10-hydroxycoronaridine, 10-hydroxyheyneanine, methuenine, apparicine, tubotaiwine, 16-epi-isositsirikine, 16-epimethuenine, 3,14-dihydroellipticine, an isomer of corynantheol, 16-epimethuenine N-oxide and tetra-hydroellipticine.     

Alkaloids of melodinus guillauminii

Fourteen alkaloids were isolated from the stem bark and aerial parts of Melodinus guillauminii. They were 11-hydroxytabersonine, venalstonine, venalstonidine, 14,15-seco-3-oxokopsinal, 3-oxovenalstonine, 11-methoxy-Δ¹⁴– vincamenine, 3-oxo-hydroxykopsinine, 11-methoxy-Δ¹⁴-vincanol, kopsinine, 15-α-hydroxykopsinine, 11-methoxy- tabersonine, pleiocarpamine, 19-β-hydroxyvenalstonine and guillauminiine.     

Na-formylechitamidine,an alkaloid from Alstonia boonei

A known alkaloid, echitamidine, and a new alkaloid, N_a-formylechitamidine, have been isolated from the stem bark of Alstonia boonei. The structure of this new alkaloid was assigned on the basis of chemical and spectroscopic data.     

Indole alkaloids from Hunteria zeylanica

Fourteen indole alkaloids were isolated and identified from the leaves and bark of Hunteria zeylanica: isocorymine, vobasine, (+)-eburnamenine, eburnamine, isoeburnamine, O-ethyleburnamine, O-methyleburnamine, O-methylisoeburnamine, pleiocarpamine, dihydrocorynantheol, yohimbol, epiyohimbol, tuboxenine and hydroxy-17-decarbomethoxy-16-dihydroepiajmalicine. O-Ethyleburnamine, O-methylisoeburnamine, epiyobimbol and hydroxy-17-decarbomethoxy-16-dihydroepiajmalicine, although known products, were isolated for the first time from a natural source.     

Alstolenine, 19,20-dihydropolyneuridine and other minor alkaloids of the leaves of Alstonia venenata

Structures of alstolenine and 19,20-dihydropolyneuridine, two new indole alkaloids of the leaves of Alstonia venenata have been established. In add     

Further alkaloids of Alstonia muelleriana

Five further alkaloids, des-N′_a-methylanhydromacralstonine, quebrachidine, vinervinine, pleiocarpamine, and 2,7-dihydropleiocarpamine, have been isolated from Alstonia muelleriana bark. Phytochemical problems in the genus Alstonia are considered, especially with reference to the ‘macroline-derived’ indole and bis-indole alkaloids.     

Alkaloids of Rauwolfia cumminsii stem

24 indole alkaloids were isolated from the stem bark of Rauwolfia cumminsii and 21 identified. The alkaloids comprised E-seco, sarpagan, dihydroindole, yohimbine, heteroyohimbine, 18-hydroxyyohimbine ester and anhydronium types together with peraksine and deacetylpicraline. The probable biosynthesis of the alkaloids is discussed.