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Cyclohexane-fused octahydroquinolizine (COHQ) alkaloids present an unwonted carbon framework among alkaloids isolated from genus Myrioneuron, which featured with bridge-ring and hemiacetal groups. Continued chemical investigation of Myrioneuron faberi led to the isolation of four COHQ related structures, β-myrifabral C (1), α-myrifabral C (2), β-myrifabral D (3), and α-myrifabral D (4). 1 and 2 were inseparable hemiacetal epimers (cluster A), as did 3 and 4 (cluster B). The structures of 1–4 were elucidated on basis of MS and NMR spectra. In vitro, cluster A showed moderate inhibition activity against hepatitis C virus (HCV) replication with therapeutic index (CC50/EC50) of 74.0.

Two novel Myrioneuron alkaloids, schoberine B (1) and myriberine B (2), were isolated from the aerial part of Myrioneuron faberi. Schoberine B is the first example among lysine-originating alkaloids to possess a ring-free C5 fragment as a side chain. The structures of 1 and 2 were elucidated using analyses of extensive NMR and MS spectra. 1 and 2 were evaluated in vitro against hepatitis C virus (HCV), showing a therapeutic index (CC50/EC50) of higher than 36.2 and 15.2, respectively.

Myrioneuron alkaloids are a class of fast growing natural products elaborated by plants of the genus Myrioneuron. Three new alkaloids secomyrionamide (1), isomyrionine (2), and 12-oxomyriberine A (3) were isolated from Myrioneuron faberi. 1 and 2 presenting the simplest two members of alkaloids derived from M. faberi, and possessing tricyclic C-15 carbon framework, which might furnish precursors for myrionamide and bring new insight into biosynthesis pathway of myrionamide. Structures of 1-3 were elucidated on basis of NMR and MS spectra. Compounds 2 and 3 were tested for inhibitory activity to the hepatitis C virus (HCV), and showed weak activity. (C) 2016 Elsevier Ltd. All rights reserved.

A strategy has been developed that culminated in a stereoselective total synthesis of the tetracyclic antimalarial Myrioneuron alkaloid myrioneurinol. The synthesis relies on three highly diastereoselective reactions, including an intramolecular chelation-controlled Michael spirocyclization of an N-Cbz-lactam titanium enolate to an α,β-unsaturated ester for construction of the A/D-ring system and the attendant C5 (quaternary), C6 relative stereochemistry; a malonate enolate conjugate addition to a nitrosoalkene in order to install the appropriate functionality and establish the configuration at C7; and an intramolecular aza-Sakurai reaction to form the B-ring and the accompanying C9 and C10 stereocenters.

Myrioneuron alkaloids are a class of fast growing natural products elaborated by plants of the genus Myrioneuron. Three new alkaloids secomyrionamide (1), isomyrionine (2), and 12-oxomyriberine A (3) were isolated from Myrioneuron faberi. 1 and 2 presenting the simplest two members of alkaloids derived from M. faberi, and possessing tricyclic C-15 carbon framework, which might furnish precursors for myrionamide and bring new insight into biosynthesis pathway of myrionamide. Structures of 1-3 were elucidated on basis of NMR and MS spectra. Compounds 2 and 3 were tested for inhibitory activity to the hepatitis C virus (HCV), and showed weak activity. (C) 2016 Elsevier Ltd. All rights reserved.

Four new Myrioneuron alkaloids, mysumamides A-D (1-4), along with three known ones were isolated from the twigs and leaves of Myrioneuron effusum. All of these alkaloids possessed the tetracyclic skeleton and contained the decahydroquinoline (cis-DHQ) moiety. Their structures and relative configurations were elucidated on the basis of spectroscopic methods, especially 2D NMR techniques. The absolute configuration of 1 was determined by single-crystal X-ray diffraction. The cytotoxic activities of these compounds were also evaluated in vitro.

Myritonines A–C (1–3), three new alkaloids bearing an unprecedented heterohexacyclic skeleton, were isolated from Myrioneuron tonkinensis. Their structures were determined by a combination of spectroscopic data and single-crystal X-ray diffraction analysis. Compound 3 represents the first Myrioneuron alkaloid featuring a unique trans-decahydroquinoline motif and was also found to possess a rare cyano functionality. Compounds 1 and 2 showed inhibition against the hepatitis C virus in vitro.

The first total synthesis of the Myrioneuron alkaloids (±)-α,β-myrifabral A and B has been accomplished in only four steps from conveniently available starting materials. This short synthesis relied on the use of a key tandem Mannich/amidation reaction to rapidly construct the core framework and two carbon stereocenters. The synthetic route allows for large scale preparation of these promising natural products against the hepatitis C virus (HCV).

This Concept article describes how key C10 molecular scaffolds, too reactive to be obtained through classical multistep synthesis, were targeted in the most simple reaction conditions, reproducing those that may be encountered in living cells. The rationale was that small amounts of these reactive intermediates might be formed in situ from cheap and abundant reactants (i.e., glutaraldehyde and tetrahydropyridine) resulting, upon further rearrangement in “complex mixtures” from which natural substances would arise. From five types of mixtures, at least six full carbon skeletons of known natural substances were formed spontaneously. This work also led to the discovery of new plausible biosynthetic achiral precursors in the Nitraria metabolism.

One Myrioneuron alkaloid, myrifabine (1), the first example of a dimer with 12 chiral centers embraced in a decacyclic novel skeleton, was isolated from Myrioneuron faberi . Its structure was elucidated by spectroscopic data and single-crystal X-ray diffraction. The antimicrobial and cytotoxic activities of 1 were evaluated in vitro.

Covering: up to November 2009 This review describes a wide panel of alkaloids isolated from plants of the Nitraria genus, focusing on their biosynthesis and discussing the resulting biomimetic chemistry in relevant cases. The scope is purposely limited to alkaloids derived at least to some extent from L-lysine, considering that most of these molecules have unique structures and are specific to the genus. Some of the biosynthetic pathways described are taken from the literature, but others are proposed here for the first time. The latter are mostly hypotheses justified by the fact that they are based on metabolic routes frequently encountered for other Nitraria alkaloids, and thus permit unification of the biosynthesis around common pivotal biosynthetic intermediates. Myrioneuron alkaloids are also presented as a newly discovered class with striking similarities to Nitraria alkaloids.

Covering: up to November 2009 This review describes a wide panel of alkaloids isolated from plants of the Nitraria genus, focusing on their biosynthesis and discussing the resulting biomimetic chemistry in relevant cases. The scope is purposely limited to alkaloids derived at least to some extent from L-lysine, considering that most of these molecules have unique structures and are specific to the genus. Some of the biosynthetic pathways described are taken from the literature, but others are proposed here for the first time. The latter are mostly hypotheses justified by the fact that they are based on metabolic routes frequently encountered for other Nitraria alkaloids, and thus permit unification of the biosynthesis around common pivotal biosynthetic intermediates. Myrioneuron alkaloids are also presented as a newly discovered class with striking similarities to Nitraria alkaloids.