Lycopladine H, a novel alkaloid with fused-tetracyclic skeleton from Lycopodium complanatum

A novel Lycopodium alkaloid, lycopladine H (1), with a fused-tetracyclic ring system consisting of an azocane ring connected to a [2,2,2]-bicyclooctane ring and a 3-piperidone ring, was isolated from the club moss Lycopodium complanatum. The structure and relative stereochemistry of 1 were elucidated on the basis of spectroscopic data.     

Lycopladines F and G, new C16N2-type alkaloids with an additional C4N unit from Lycopodium complanatum

Two new Lycopodium alkaloids, lycopladines F (1) and G (2), have been isolated from the club moss Lycopodium complanatum, and the structures and relative stereochemistries of 1 and 2 were elucidated on the basis of spectroscopic data. Lycopladine F (1) is a rare C₁₆N₂-type Lycopodium alkaloid possessing an amino acid residue (C₄N).     

Lyconadins C and F, new Lycopodium alkaloids from Lycopodium complanatum

New Lycopodium alkaloids, lyconadins C (1) and F (2), were isolated from the club moss Lycopodium complanatum. Lyconadin C (1) is a new C₁₆N₂-type Lycopodium alkaloid possessing unique fused-tetracyclic ring system consisting of a cycloheptene ring fused to a decahydroquinoline and pyridone rings. Lyconadin F (2) possesses a primary amide moiety in its molecular, which is the first example of Lycopodium alkaloids. Biogenetically, lyconadins C (1) and F (2) might be related to lyconadins A (4) and B (5). The structures and relative stereochemistry of 1 and 2 were elucidated on the basis of spectroscopic data. The absolute stereochemistry of 2 was elucidated by chemical correlations with lyconadin B (5) through hemiaminal form of lyconadin F (3).     

Senepodines B-E, new C22N2 alkaloids from Lycopodium chinense

Four new C₂₂N₂Lycopodium alkaloids, senepodines B-E (2-5), consisting of an octahydroquinoline ring and a quinolizidine ring have been isolated together with senepodine A (1) from the club moss Lycopodium chinense. The relative and absolute stereochemistry of 2-5 were determined by combination of NOESY correlations and chemical transformation, while the absolute configuration of 1 was assigned by exciton chirality method.     

Hupermine A,a novel C16N2-type Lycopodium alkaloid from Huperzia phlegmaria

A novel C₁₆N₂-type Lycopodium alkaloid consisting of a quinolizidine with a 6-dimethylaminohexyl side chain, hupermine A (1), was isolated from the club moss of Huperzia phlegmaria, and the structure and relative stereochemistry were elucidated on the basis of spectroscopic data.     

Lycogladines A-H,fawcettimine-type Lycopodium alkaloids from Lycopodium complanatum var. glaucum Ching

Five new fawcettimine-type alkaloids (1–5) and three new natural products (6–8), along with four known analogues, fawcettimine (9), fewcettidine (10), lycopoclavamine B (11), and lycopladine B (12), were isolated from the whole plant of Lycopodium complanatum var. glaucum Ching. The structures of lycogladines A-H (1–8) were determined based on HRESIMS, 1D and 2D NMR spectroscopic analysis, as well as single-crystal X-ray diffraction. Compound 1 possesses a new ring system that is formed through the linkage of C-13-OC-2, which is rarely present in Lycopodium alkaloids (LAs). Compounds 1–8 were tested for their β-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) and acetylcholinesterase (AChE) inhibitory activities.     

Vilmoraconitine, a novel skeleton C19-diterpenoid alkaloid from Aconitum vilmorinianum

A novel C₁₉-diterpenoid alkaloid vilmoraconitine (1) was isolated from the roots of Aconitun vilmorinianum. Its structure was mainly determined by MS, 2D NMR, and X-ray methods. This is the first aconitine-type C₁₉-diterpenoid alkaloid with one three-membered ring at C-8, C-9, and C-10.     

Campylopin from Delphinium campylocentrum, the first hetidane C20-diterpene, suggests a new alkaloid biogenetic pathway

A novel C₂₀-diterpene, campylopin (1), was isolated from the whole herb of Delphinium campylocentrum. The elucidation of its structure was accomplished through extensive spectroscopic methods. Compound 1 represents the first hetidane-type diterpene skeleton, which may imply a new biosynthetic pathway from the atisane or hetidane-type diterpene to the hetidine-type diterpenoid alkaloid.     

Lycobelines A-C, Novel C16N2-type Lycopodium alkaloids from Huperzia goebelii

Novel C₁₆N₂-type Lycopodium alkaloids consisting of a decahydroquinoline with an aminohexyl side chain, lycobelines A-C (1-3), were isolated from the club moss of Huperzia goebelii, and their structures and relative stereochemistry were elucidated on the basis of spectroscopic data and chemical correlations.     

Sarusubine A, a new dimeric Lythraceae alkaloid from Lagerstroemia subcostata

A new dimeric Lythraceae alkaloid with a cyclobutane ring, sarusubine A (1), has been isolated from the leaves of Lagerstroemia subcostata, and the structure and stereochemistry were elucidated by spectroscopic data.     

Ervahainine A,a new cyano-substituted oxindole alkaloid from Ervatamia hainanensis

Ervahainine A (1), a new cyano-substituted oxindole alkaloid, was isolated from Ervatamia hainanensis. The structure was elucidated on the basis of spectroscopic methods and further confirmed by the single-crystal X-ray diffraction analysis. Ervahainine A exhibited potential inhibition against two human cancer cell lines.     

Subnitride chemistry: A first-principles study of the NaBa3N, Na5Ba3N, and Na16Ba6N phases

An ab initio study on the electronic structure of the subnitrides NaBa₃N, Na₅Ba₃N, and Na₁₆Ba₆N is performed for the first time. The NaBa₃N and Na₅Ba₃N phases consist of infinite ¹_∞[NBa_6/2] strands composed of face-sharing NBa₆ octahedra surrounded by a “sea” of sodium atoms. The Na₁₆Ba₆N phase consist of discrete [NBa₆] octahedra arranged in a body-cubic fashion, surrounded by a “sea” of sodium atoms. Our calculations suggest that the title subnitrides are metals. Analysis of the electronic structure shows partial interaction of N(2s) with Ba(5p) electrons in the lower energy region for NaBa₃N and Na₅Ba₃N. However, no dispersion is observed for the N(2s) and Ba(5p) bands in the cubic phase Na₁₆Ba₆N. The metallic band below the Fermi level shows a strong mixing of N(2p), Ba(6s), Ba(5d), Ba(6p), Na(3s) and Na(3p) orbitals. The metallic character in these nitrides stems from delocalized electrons corresponding to hybridized 5d^l6s^m6pⁿ barium orbitals which interact with hybridized 3sⁿ3p^m sodium orbitals. Analysis of the electron density and electronic structure in these nitrides shows two different regions: a metallic matrix corresponding to the sodium atoms and the regions around them and heteropolar bonding between nitrogen and barium within the infinite ¹_∞[NBa_6/2] strands of the NaBa₃N and Na₅Ba₃N phases, and within the isolated [NBa₆] octahedra of the Na₁₆Ba₆N phase. The nitrogen atoms inside the strands and octahedra are negatively charged, the anionic character of nitrogens being larger in the isolated octahedra of the cubic phase Na₁₆Ba₆N, due to the lack of electron delocalization along one direction as opposed to the other phases. The sodium and barium atoms appear to be slightly negatively and positively charged, the latter to a larger extent. From the computed Ba-N overlap populations as well as the analysis of the contour maps of differences between total density and superposition of atomic densities, we suggest partial covalent bonding between nitrogen and barium atoms along the infinite ¹_∞[NBa_6/2] strands and within isolated [NBa₆] octahedra.     

Kingamide A, a new indole alkaloid from the ascidian Leptoclinides kingi

Chemical investigation of the CH₂Cl₂/MeOH extract from the Australian ascidian Leptoclinideskingi led to the isolation of a new brominated indole alkaloid, kingamide A (1). The planar structure of kingamide A was elucidated following the interpretation of 1D/2D NMR and MS data, and the absolute configuration was determined using Marfey’s method. This is the first report of a natural product from L. kingi.     

Accurate hyperfine couplings for C59N

We identify the shortcomings of existing ab initio quantum chemistry calculations for the hyperfine couplings in the recently characterized azafullerene, C₅₉N. Standard gaussian basis sets in the context of all-electron calculations are insufficient to resolve the spin density near the cores of the atoms. Using the projector augmented wave (PAW) method implemented on top of a standard pseudo-potential plane-wave density-functional framework, we compute significantly more accurate values for the Fermi contact interaction.     

A new pyrrolizidine alkaloid from Senecio Latifolius DC

The structure of a new pyrrolizidine alkaloid, merenskine N-oxide [1], was determined by spectroscopic methods which included NMR SPI experiments to indicate the mode of esterification.     

Speradine A, a new pentacyclic oxindole alkaloid from a marine-derived fungus Aspergillus tamarii

A new pentacyclic oxindole alkaloid, speradine A (1), was isolated from the cultured broth of a fungus Aspergillus tamarii, which was separated from driftwood at a seashore in Okinawa. The structure and relative stereochemistry were determined by spectroscopic data and a single crystal X-ray diffraction analysis.     

Oldhamine A, a novel alkaloid from Daphniphyllum oldhami

Oldhamine A, a novel alkaloid with an unusual cyclopentadienyl anion in the fused-pentacyclic skeleton was isolated from the twigs of Daphniphyllum oldhami. The structure of oldhamine A was elucidated based on the spectroscopic data and the single-crystal X-ray diffraction crystallography. It is the first X-ray diffraction of the Daphniphyllum alkaloids with nitrogen-containing two pentacyclic rings. The inter-conversion between cyclopentadienyl anion and conjugated enolic unit was also conducted.