ABSTRACT
A total of 20 new indole alkaloids comprising mainly oxidized derivatives of macroline- (including alstofonidine, a macroline indole incorporating a butyrolactone ring-F), pleiocarpamine-, and sarpagine-type alkaloids were isolated from the bark and leaf extracts of Alstonia angustifolia. The structures and relative configurations of these alkaloids were determined using NMR and MS analyses and in some instances confirmed by X-ray diffraction analyses. Alkaloids 3, 7, 35, and 41 showed moderate to weak activity, while 21 showed strong activity in reversing multidrug resistance in vincristine-resistant KB cells.
Subject(s)
Alstonia/chemistry , Indole Alkaloids/isolation & purification , Alkaloids , Crystallography, X-Ray , Humans , Indole Alkaloids/chemistry , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Oxidation-Reduction , Oxindoles , Plant Leaves/chemistry , Vincristine/pharmacologyABSTRACT
Nine bisindole alkaloids, comprising four belonging to the macroline-sarpagine group, and five belonging to the macroline-pleiocarpamine group, were isolated from the stem-bark extracts of Alstonia angustifolia (Apocynacea). Their structures were established using NMR and MS analyses.
Subject(s)
Alkaloids/chemistry , Alstonia/chemistry , Indole Alkaloids/chemistry , Magnetic Resonance Spectroscopy , Mass Spectrometry , Molecular Structure , OxindolesABSTRACT
Five new nitrogenous compounds were isolated from the Malayan Alstonia angustifolia and their structures determined based on interpretation of spectroscopic data.
Subject(s)
Alkaloids/chemistry , Alstonia/chemistry , Molecular StructureABSTRACT
Three new bisindole alkaloids of the macroline-macroline type, perhentidines A-C (1-3), were isolated from the stem-bark extract of Alstonia macrophylla and Alstonia angustifolia. The structures of these alkaloids were established on the basis of NMR and MS analyses. The absolute configurations of perhentinine (4) and macralstonine (5) were established by X-ray diffraction analyses, which facilitated assignment of the configuration at C-20 in the regioisomeric bisindole alkaloids perhentidines A-C (1-3). A potentially useful method for the determination of the configuration at C-20 based on comparison of the NMR chemical shifts of the bisindoles and their acetate derivatives, in these and related bisindoles with similar constitution and branching of the monomeric units, is also presented.
Subject(s)
Alstonia/chemistry , Indole Alkaloids/chemistry , Indole Alkaloids/isolation & purification , Crystallography, X-Ray , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Oxindoles , Plant Bark/chemistryABSTRACT
Four new linearly fused bisindole alkaloids, lumutinines A-D (1-4), were isolated from the stem-bark extract of Alstonia macrophylla. Lumutinines A (1) and B (2) represent the first examples of linear, ring A/F-fused macroline-macroline-type bisindoles, while lumutinines C (3) and D (4) were constituted from the union of macroline and sarpagine moieties. A reinvestigation of the stereochemical assignment of alstoumerine (8) by NMR and X-ray diffraction analyses indicated that the configuration at C-16 and C-19 required revision.
Subject(s)
Alstonia/chemistry , Indole Alkaloids/isolation & purification , Crystallography, X-Ray , Humans , Indole Alkaloids/chemistry , Malaysia , Molecular Conformation , Molecular Structure , Nuclear Magnetic Resonance, BiomolecularABSTRACT
A total of 20 alkaloids were isolated from the leaf and stem-bark extracts of Alstonia angustiloba, of which two are hitherto unknown. One is an alkaloid of the angustilobine type (angustilobine C), while the other is a bisindole alkaloid angustiphylline, derived from the union of uleine and secovallesamine moieties. The structures of these alkaloids were established using NMR and MS analysis. Angustilobine C showed moderate cytotoxicity towards KB cells.
Subject(s)
Alstonia/chemistry , Antineoplastic Agents, Phytogenic/therapeutic use , Indole Alkaloids/isolation & purification , Indole Alkaloids/therapeutic use , Neoplasms/drug therapy , Phytotherapy , Plant Extracts/therapeutic use , Alkaloids/chemistry , Alkaloids/isolation & purification , Antineoplastic Agents, Phytogenic/isolation & purification , Antineoplastic Agents, Phytogenic/pharmacology , Cell Line, Tumor , Humans , Indole Alkaloids/chemistry , Indole Alkaloids/pharmacology , Magnetic Resonance Spectroscopy , Mass Spectrometry , Molecular Structure , Plant Bark/chemistry , Plant Extracts/chemistry , Plant Extracts/pharmacology , Plant Leaves/chemistry , Plant Stems/chemistryABSTRACT
A total of 25 alkaloids were isolated from the leaf and stem-bark extracts of Alstonia spatulata, of which five are new alkaloids of the strychnan type (alstolucines A-E, 1-5) and the other, a new alkaloid of the secoangustilobine A type (alstolobine A, 6). The structures of these alkaloids were established using NMR and MS analysis and, in the case of alstolucine B (2), also confirmed by X-ray diffraction analysis. A reinvestigation of the stereochemical assignment of scholaricine (13) by NMR and X-ray analyses indicated that the configuration at C-20 required revision. Alkaloids 1, 2, 6, 7, 9, 10, and 13 reversed multidrug resistance in vincristine-resistant KB cells.
Subject(s)
Alstonia/chemistry , Indole Alkaloids/isolation & purification , Crystallography, X-Ray , Drug Resistance, Neoplasm/drug effects , Humans , Indole Alkaloids/chemistry , Indole Alkaloids/pharmacology , KB Cells , Malaysia , Molecular Conformation , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Plant Bark/chemistry , Plant Leaves/chemistry , Vincristine/pharmacologyABSTRACT
A cytotoxic bisindole alkaloid possessing an unprecedented structure in which two indole moieties are bridged by an aromatic spacer unit has been isolated from Alstonia angustifolia. The structure was established by analysis of the spectroscopic data and confirmed by X-ray diffraction analysis. A possible biogenetic pathway from pyrocatechuic acid and pleiocarpamine is presented.
