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Ten new indole alkaloids of the aspidofractinine type, in addition to several recently reported indole alkaloids and 20 other known alkaloids, were obtained from the leaf and stem-bark extract of the Malayan Kopsia singapurensis, viz., kopsimalines A-E (1-5), kopsinicine (6), kopsofinone (7), and
Three new indole alkaloids, named kopsihainins A-C (1-3), and two known compounds, kopsinine (4) and methyl demethoxycarbonylchanofruticosinate (5), were isolated from the stems of Kopsia hainanensis. Their structures were determined using extensive spectroscopic methods. The two main constituents 4
Two new monoterpene indole alkaloids, characterized by previously unencountered natural product skeletons, viz., arborisidine (1), incorporating indolizidine and cyclohexanone moieties fused to an indole unit, and arbornamine (2), incorporating an unprecedented 6/5/6/5/6 "arbornane" skeleton
Six alkaloids belonging to the methyl chanofruticosinate group, viz., prunifolines A-F, in addition to six other known methyl chanofruticosinate alkaloids, were isolated from the leaf extract of Kopsia arborea. The structures were determined using NMR and MS analysis and comparison with known
Five new aspidofractinine-type alkaloids, kopsiahainins A-E (1-5), were isolated from a 80% EtOH extract of the leaves and stems of Kopsia hainanensis. Structural elucidation of all the compounds were performed by spectral methods such as 1D- and 2D-NMR, IR, UV, and HR-ESI-MS. Alkaloids 3 and 4
Three new indole alkaloids (1-3), named grandilodines A-C, and five known ones were obtained from the Malayan Kopsia grandifolia. The structures were established using NMR and MS analyses and, in the case of 1 and 2, were confirmed by X-ray diffraction analyses. Alkaloids 1, 3, and lapidilectine B
A phytochemical investigation on the 90% ethanol aqueous extract of the aerial part of Kopsia arborea led to the isolation of three new monoterpenoid indole alkaloids, kopsiarborines A-C (1-3). The new structures were elucidated by using spectroscopic data (NMR, IR, UV, and MS). The
Five new alkaloids, including three 19,20-epoxytubotaiwine stereoisomers, viz. kopsiyunnanines F1 (1), F2 (2), and F3 (3), (Z)-isocondylocarpine (4), and (Z)-isocondylocarpine N-oxide (5), along with five known tubotaiwine-type indole alkaloids were isolated from the aerial part of Yunnan Kopsia
The total synthesis of Kopsia lapidilecta alkaloid (+/-)-lapidilectine B is described. Notable elements of this synthesis include the first natural products application of the Smalley azido-enolate cyclization to form the 1,2-dihydro-3H-indol-3-one (indoxyl) core and installation of the pyrrolidine
A new pentacyclic indole alkaloid, kopsiyunnanine E, was isolated from Yunnan Kopsia arborea, and its structure, which was inferred from spectroscopic data, was established by a 16-step asymmetric total synthesis that proved that the natural alkaloid was not enantiomerically pure.
A chemical investigation on the 80% EtOH extract of the aerial parts of Kopsia fruticosa led to five new indole alkaloids, kopsifolines G-K (1-5), and one known alkaloid, kopsifoline A (6). Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D (1H-1H COSY,
Nine new indole alkaloids, rhazinoline (1), 19(S)-methoxytubotaiwine (2), 19(R)-methoxytubotaiwine (3), kopsamidine A (4), kopsamidine B (5), kopsinidine A (6), kopsinidine B (7), paucidactine C (8), and pericine N-oxide (9), in addition to several recently reported novel indoles and 34 other known
Three new indole alkaloids, named kopsihainin D (1), kopsihainin E (2), and kopsihainin F (3), along with nine known compounds (4-12) were isolated from the twigs of Kopsia hainanensis. The structures of the new compounds were elucidated by spectroscopic methods including HRESIMS, UV, IR, and NMR.
Intravenous injection of the aspidofractinine alkaloid, kopsingine (1, 0.2-10.0 mg/kg) from Kopsia teoi, produced dose-related decreases in the mean arterial blood pressure and heart rate in anesthetized spontaneously hypertensive rats, which were similar to those seen in normotensive controls.
Three new alkaloids were isolated from the bark extract of the Malayan Kopsia arborea, viz., arbophyllidine (1), an unusual pentacyclic, monoterpenoid indole characterized by an absence of oxygen atoms and incorporating a new carbon-nitrogen skeleton, and arbophyllinines A (2)