New Indole Alkaloids from Kopsia. Alkaloid Variation in Kopsia singapurensis

Five new indole alkaloids, viz., kopsiloscine G ( 2 ), kopsidarine ( 4 ), kopsimaline F ( 6 ), kopsidine C N‐oxide ( 7 ), and aspidophylline B ( 9 ), in addition to 17 other known alkaloids, were obtained from the leaf and stem‐bark extract of the Malaysian Kopsia singapurensis. The structures were determined by using NMR and MS analysis. The results are compared with the alkaloidal composition of another sample of K. singapurensis, collected from the same location but at a different time of the year, as well as with other samples of K. singapurensis collected from different locations.     

Seven New Monoterpenoid Indole Alkaloids from Gelsemium elegans

Seven new indole alkaloids were isolated from the roots of Gelsemium elegans Benth. and their structures were determined by spectroscopic analysis and chemical transformation from known alkaloids. Kounaminal ( 1 ) is a new koumine‐type alkaloid that contains an unusual aminal moiety. Humantenoxenine ( 2 ) and 15‐hydroxyhumantenoxenine ( 3 ) are humantenine‐type alkaloids that contain a novel β‐amino‐α,β‐unsaturated ketone residue. The other four novel alkaloids are two gelsedilam‐related and two gelsenicine‐related alkaloids.     

Three New Monoterpenoid Indole Alkaloids from Ervatamia flabelliformis

The three new monoterpenoid indole alkaloids 1 – 3 were isolated from the stems of Ervatamia flabelliformis. The structures were elucidated on the basis of spectral analysis and chemical derivatization.     

Monoterpenoid Indole Alkaloids from Alstonia mairei

Three new monoterpenoid indole alkaloids, (14α,15α)‐14,15‐epoxyaspidofractinine ( 1 ) and maireines A and B ( 2 and 3 , resp.), together with 19 known alkaloids, were isolated from the leaves and twigs of Alstonia mairei. The structures of the new compounds were elucidated by 1D‐ and 2D‐NMR spectroscopic methods in combination with MS experiments.     

Three New Indole Alkaloids from the Leaves of Kopsia officinalis

Three new indole alkaloids, 11,12‐de(methylenedioxy)danuphylline ( 1 ), methyl (2β,11β,12β,19α)‐6,7‐didehydro‐8,21‐dioxo‐11,21‐cycloaspidospermidine‐2‐carboxylate ( 2 ), and (2β,5β)‐aspidofractinin‐16‐ol ( 3 ) were isolated from Kopsia officinalis, together with 16 known compounds. Their structures were determined by spectroscopic methods. The isolated known compound (?)‐12‐methoxykopsinaline displayed antimanic effects in Drosophila, with an IC₅₀ value of 12.5 μg/ml.     

云南蕊木茎中的抗炎吲哚生物碱

应用多种色谱和波谱学方法,从云南蕊木(Kopsia officinalis)茎中分离鉴定了27个单萜吲哚生物碱,包括7个新化合物kopsiofficines A～G和20个已知化合物.此外,建立脂多糖(LPS)诱导的小鼠巨噬细胞RAW 264.7炎症模型,通过测定IL-1β, PGE2和TNF-α炎症因子释放评价生物碱的抗炎活性.结果表明, kopsiofficines A (1), kopsiofficines B (2),kopsiofficines D(4),kopsiofficines F(6),kopsiofficines G(7), 12-methoxykopsine(11),kopsinoline(15),(-)-N-methoxy-carbonyl-11,12-methylenedioxykopsinaline(16),kopsinine(18)和kopsinic acid(20)表现出显著的抗炎活性,与阳性对照(地塞米松)基本相当.研究发现C-5位丙酮基取代的单萜吲哚生物碱的抗炎活性明显强于原型生物碱,推测丙酮基可能是抗炎活性的药效促进基团,研究结果为进一步的结构修饰...     

Asymmetric Total Syntheses of Kopsia Indole Alkaloids

The asymmetric total syntheses of a group of structurally complex Kopsia alkaloids, (−)‐kopsine, (−)‐isokopsine, (+)‐methyl chanofruticosinate, (−)‐fruticosine, and (−)‐kopsanone, has been achieved. The key strategies for the construction of the molecular complexity in the targets included an asymmetric Tsuji–Trost rearrangement to set the first quaternary carbon center at C20, an intramolecular cyclopropanation by diazo decomposition to install the second and third quaternary carbon centers at C2 and C7, respectively, and a SmI₂‐promoted acyloin condensation to assemble the isokopsine core. A radical decarboxylation of an isokopsine‐type intermediate results in a thermodynamic partial rearrangement to give N‐decarbomethoxyisokopsine and N‐decarbomethoxykopsine, two key intermediates for the syntheses of Kopsia alkaloids with different subtype core structures.     

Vinmajorines C – E,Monoterpenoid Indole Alkaloids from Vinca major

Three new monoterpenoid indole alkaloids, vinmajorines C–E ( 1 – 3 ), along with 18 known analogues ( 4 – 21 ), were isolated from the whole plants of Vinca major. The new structures were elucidated as (5α,15β,16R,17α,19β,20α,21β)‐10,17‐dimethoxy‐21‐methyl‐18‐oxa‐5,16‐cycloyohimban‐19‐ol ( 1 ), (5α,15β,16R,17α,20α,21β)‐10‐methoxy‐21‐methyl‐18‐oxa‐5,16‐cycloyohimban‐17‐ol ( 2 ), and (5α,15β,16R,17α,20α,21β)‐10‐methoxy‐21‐methyl‐18‐oxa‐5,16‐cycloyohimban‐17‐yl acetate ( 3 ), respectively, by extensive NMR and MS analysis and comparison with known compounds. Compounds 1 – 3 were evaluated for their cytotoxic activities against five human cancer cell lines, compounds 1 and 3 showing moderate cytotoxic activities.     

Monoterpenoid Indole Alkaloids with Promoting Neurite Growth from Tabernaemontana divaricata

Main observation and conclusion Phytochemical investigations on Tabernaemontana divaricata led to the isolation of seven undescribed monoterpenoid indole alka-l...     

Formation of the First Trimeric Monoterpenoid Indole Alkaloids

Under O², the Aspidosperma alkaloid tabersonine ( 1 ) was converted by a crude enzyme preparation from leaves of mature plants of Catharanthus roseus G DON into the trimeric 3-hydroxy-14′-(3α″-tabersonyl)voafrine B ( 4 ) which was easily reduced by NaBH₄ to 14′-(3α″-tabersonyl)voafrine B ( = tertabersonine; 5 ). Compounds such as 4 and 5 are the first trimeric alkaloids in the series of monoterpenoid indole alkaloids.     

Monoterpenoid Indole Alkaloids Bearing an N4‐Iridoid from Gelsemium elegans

Five new alkaloids, gelseganines A–D ( 1 – 4 ) and humantenine N₄‐oxide ( 5 ), were isolated from the stems and leaves of Gelsemium elegans. Compounds 1 – 4 represent a rare class of monoterpenoid indole alkaloids that bear an N₄‐iridoid unit. The structures of 1 – 5 were determined by spectroscopic analysis, single‐crystal X‐ray diffraction, and chemical correlation, and their absolute configurations were elucidated by CD analysis. A plausible biogenetic pathway for alkaloids 1 – 5 was also postulated.     

A Facile Chemoenzymatic Approach: One‐Step Syntheses of Monoterpenoid Indole Alkaloids

Facile chemoenzymatic syntheses of cytotoxic monoterpenoid indole alkaloids with novel skeletons and multiple chiral centers are described. Synthesis of these alkaloids was achieved by a simple one‐step reaction using strictosidine and 12‐aza‐strictosidine as the key intermediates. Strictosidines were prepared by coupling of secologanin with tryptamine and 7‐aza‐tryptamine, respectively, using the immobilized recombinant Rauvolfia strictosidine synthase. A detailed stereochemical analysis is presented herein. The results provide an opportunity for a chemoenzymatic approach that leads to an increased diversification of complex alkaloids with improved structures and activities.     

单萜吲哚生物碱的仿生合成

单萜吲哚生物碱因其骨架和官能团的丰富变化,加上它们的生物活性,多年来 一直哟引着一代又一代的化学家对其进行结构和合成研究,它们的共同生物合成前 体strictosidine是由色胺和单萜苷secologanin缩合形成的。自从secologanin可 以大量得到以后,以它为原料沿着可能的生物合成路线合成天然生物碱即仿生合成 就成为一个重要的研究领域。它对于理解和阐释生物碱的生物合成过程,为提供天 然来源极少的生物碱供药理试验及对促进有机合成化学的发展等都是有重要意义。 这方面的研究也取得了许多重要进展,成功合成了一些重要的单萜吲哚生物碱,如 育亨宾类、钩藤碱、异钩藤碱、卡得宾、利血平类似物、喜树碱等。     

Discovery of Natural Co-occurring Enantiomers of Monoterpenoid Indole Alkaloids

Two new pairs of monoterpenoid indole alkaloids (MIAs) enantiomers as well as their new congeners were isolated from stems of Tabernaemontana bovina Lour.(Apocy...     

Longistylumphyllines A–C,Three New Alkaloids from Daphniphyllum longistylum

Three new alkaloids, longistylumphyllines A–C (1–3), together with the six known alkaloids deoxycalyciphylline B, deoxyisocalyciphylline B, methyl homosecodaphniphyllate, daphnicyclidin A, daphnicyclidin B, and daphnicyclidin F, were isolated from the stems and leaves of Daphniphyllum longistylum. Their structures and relative configuration were elucidated on the basis of spectroscopic data, especially 1D and 2D NMR techniques.