Structures Of Alkaloids Research Articles

Alkaloids from Boophone haemanthoides (Amaryllidaceae)

In this study, the South African Amaryllid Boophone haemanthoides was examined for its phytochemical composition and cytotoxicity. In the process eight alkaloid structures, including the new compound distichaminol, were identified in bulb ethanolic extracts. Of the isolates, lycorine and distichamine exhibited strong activities against human acute lymphoblastic leukemia (CEM), breast adenocarcinoma (MCF7) and cervical adenocarcinoma (HeLa) cells with IC50S ranging from 1.8 to 9.2 microM.

Towards the Core Structure of Strychnos Alkaloids Using Samarium Diiodide‐Induced Reactions of Indole Derivatives

This report describes the development of a first and second generation approach towards the synthesis of the ABCEG pentacyclic core structure of Strychnos alkaloids. First, we discuss a sequential approach applying a series of functional group transformations to prepare suitable precursors for cyclization reactions. These include attempts of samarium diiodide-induced cyclizations or a Barbier-type reaction of a transient lithium organyl, which successfully led to a tetracyclic key building block earlier used for the synthesis of strychnine. Secondly, we account our first steps towards the development of an atom-economical samarium diiodide-induced cascade reaction using "dimeric" indolyl ketones as cyclization precursors. In this context, we discuss plausible mechanisms for the samarium diiodide-induced cascade reaction as well as transformations of the obtained tetracyclic dihydroindoline derivatives.

ChemInform Abstract: Practical, Highly Stereoselective Allyl‐ and Crotylsilylation of Aldehydes Catalyzed by Readily Available Cinchona Alkaloid Amide.

We have demonstrated that bidentate Lewis base catalysts can be constructed based on the Cinchona alkaloid structure that promote highly stereoselective reactions of allyl- and crotyltrichlorosilane with aromatic as well as aliphatic aldehydes (90–99% ee, >98% diastereoselectivity). The catalysts are available in a one-pot procedure in >70% yield from cheap starting materials and promote the allylation reactions at ambient temperature. Gram scale reactions with catalyst recovery and reuse showcased the practicality of the catalytic system.

A new diketopiperazine alkaloid from Aspergillus oryzae

Investigation of bioactive secondary metabolites from terrestrial Aspergillus oryzae sp. MMAO1 using M2 medium afforded a new diketopiperazine alkaloid, 7,9-dihydroxy-3-(1H-indol-3-ylmethyl)-8-methoxy-2,3,11,11a-tetrahydro-6H-pyrazino[1,2-b]isoquinoline-1,4-dione (1a), containing the unusual amino acid l-6,8-dihydroxy-7-methoxyphenylalanine. This was co-isolated with ditryptophenaline (2), cyclo-(Tryp,Tyr) (4), cyclo-(Pro,Val), α-cyclopiazonic acid (3), kojic acid and uridine. Re-cultivation of the fungal strain on Dox medium led to the production of bisdethio(bismethylthio)gliotoxin (5), pseurotin A (6) along with linoleic acid, α-cyclopiazonic acid (3) and kojic acid. The chemical structure of the new diketopiperazine alkaloid including the relative configuration was determined by 1D and 2D NMR spectroscopy and HR-ESI-MS spectrometry, and by comparison with the related literature. The new alkaloid (1a) showed no antimicrobial activity or cytotoxicity against brine shrimps.

Iron-catalyzed carbonylation–arylation of N-arylacrylamides for synthesis of oxindole derivatives

An efficient method for oxindole synthesis is established by iron-catalyzed carbonylation–arylation of N-arylacrylamides with aldehydes. 3-Functionalized oxindoles are synthesized smoothly using FeCl3 as catalyst and TBHP as oxidant. The obtained oxindoles can be used for further transformations to give diverse indole alkaloid structure motifs.

How do Pseudoenantiomers Structurally Differ in the Gas Phase? An IR/UV Spectroscopy Study of Jet‐Cooled Hydroquinine and Hydroquinidine

The gas-phase structures of the cinchona alkaloids, hydroquinine and its pseudoenantiomer hydroquinidine, are studied in a supersonic expansion by means of laser-induced fluorescence and IR/UV double-resonance spectroscopy. Vibrational spectroscopy combined with density functional calculations show that the conformational properties of the two pseudoenantiomers are identical. In both cases, they exist in two isoenergetic forms, with similar IR spectra. Both conformers are similar to the most stable cis-γ-open form of quinine; they differ from each other by the position of the ethyl substituent attached to the quinuclidine ring. Further differences between the two conformers are observed in the laser-induced fluorescence spectrum. The first electronic transition is characterized by time-dependent density functional theory and RI-cc2 calculations, and is of ππ* nature. The results described here emphasize the role of the ethyl substituent in the structural differences between pseudoenantiomers of cinchona alkaloids.

The Akuammiline Alkaloids; Origin and Synthesis

Due to their structural diversity, elegant polycyclic molecular architecture, and biological activity, the indole alkaloids have been investigated by organic chemists over the last century. The first akuammiline alkaloid, echitamine, was isolated in 1875 and first described in 1880. Owing to the exceptional structure of akuammiline alkaloids, it was not until 125 years later that the first successful total synthesis was accomplished. This review will give an overview of this class of alkaloids, pinpointing its structural characteristics and showcasing the completed total syntheses. Furthermore, an overview of the structural diversity is given. 1 Introduction 2 Structural Analysis 3 Biosynthesis 4 Completed Total Syntheses 4.1 (±)-Vincorine 4.2 (–)-Vincorine 4.3 (±)-Aspidophylline A 4.4 (+)-Scholarisine A 5 Conclusion

Chemical constituents and ACE inhibitory activity of desert plant Suaeda physophora Pall.

Suaeda physophora Pall. is a kind of desert plant mostly growing in saline habitats in Xinjiang Uygur Autonomous Region. In order to have a better utilization of halophytes, a screening for ACE inhibitors from halophytes growing in Xinjiang was carried out. The result showed that the 70% EtOH extract and n-BuOH extract of S. physophora Pall. possessed significant ACE inhibitory activities. So we focused on its biochemical constituents firstly. One new quinazoline alkaloid, namely Suaedine (1), along with six known compounds (2–7) was isolated from the aerial parts of S. physophora Pall. The structure of the new quinazoline alkaloid was established by one- and two-dimensional nuclear magnetic resonance, optical rotation and mass spectrometry analysis. The flavonoid compounds (2–4) and phenolic compound (5) exhibited significant ACE activities. It was the first time to focus on the chemical constituents and bioactivities of this plant.

The Present Research Situation of <i>Crinum asiaticum</i> Alkaloids Active Ingredient

The basic structures of Crinum Asiaticum alkaloids are N-(3, 4-dioxo-benzyl)-4-O-phenylethylamine, pyrrole phenanthridine, 5,10b-ethanophenanthridine. The basic framework can form a new parent nucleus structure with significant pharmacological activity by oxidation, dehydrogenation, cyclization, O, N-methylation, acylation reaction. Crinum Asiaticum alkaloids antibacterial, antimalarial, anti-inflammatory, anti-cancer, inducing tumor cell apoptosis, the protection of the cardiovascular and other effects are reviewed.

Large-scale separation of alkaloids from Gelsemium elegans by pH-zone-refining counter-current chromatography with a new solvent system screening method

A rapid and simple solvent system screening method was developed for pH-zone-refining counter-current chromatography (CCC) separation, which was much easier to find a suitable solvent system than the traditional method. Using this method, an optimal solvent system composed of hexane–ethyl acetate–methanol–water (3:7:1:9, v/v) was selected for pH-zone-refining CCC separation of alkaloids from the stems of Gelsemium elegans, where 10mM triethylamine (TEA) was added to the upper organic stationary phase as a retainer and 10mM hydrochloric acid (HCl) to the aqueous mobile phase as an eluter. As a result, six oxindole alkaloids, 420mg 19-xo-gelsenicine, 456mg gelsemine, 723mg koumine, 379mg 11-methoxygelsemamide, 342mg gelsenicine and 318mg humantenine were successfully purified in one step from 4.5g crude extract with the purity of over 95%, respectively. The structures of the oxindole alkaloids were identified by ESI-MS, 1H NMR and 13C NMR.

Homology modeling of LmxMPK4 of Leishmania mexicana and virtual screening of potent inhibitors against it

Leishmaniasis is one of the most important diseases of mankind. In the life cycle of Leishmania mexicana, two most important developmental stages are observed. In insect vector it is in promastigote form and in mammalian macrophages is the amastigote form. The family of protein kinases are extremely important regulators of many different cellular processes such as transcriptional control, cell cycle development and differentiation, and also draw much attention as possible drug targets for protozaon parasites. Leishmania mexicana mitogen activated protein kinase 4 (LmxMPK4) is essential for proliferation and survival of the parasite promastigote and amastigote forms and is a potential drug target for leishmaniasis. The existing therapy for leishmaniasis is not enough due to host toxicity and drug resistance. The experimental 3D structure of this protein has not yet been determined. In this study, we have used homology modelling techniques to generate the 3D structure of LmxMPK4 and selected effective inhibitors by ZINC database on the basis of structure of berberine alkaloid for molecular docking studies with LmxMPK4. The inhibitors ZINC05999210, ZINC40402312 and ZINC40977377 were found to be more potent for inhibition of leishmaniasis due to the robust binding affinity and strong inhibition constant (Ki) of the protein-ligand interactions. This finding may help to understand the nature of MAP kinase and development of specific anti-leishmanial therapies.

Nine new lycopodine-type alkaloids from Lycopodium japonicum Thunb.

Nine new alkaloids (1–9) with lycopodine-related structures, i.e., 6α,8β-dihydroxylycopodine, 4α,8β-dihydroxylycopodine, alongside thirteen known compounds (10–22), were isolated from the club moss Lycopodium japonicum Thunb. The structures of the new alkaloids including their absolute configurations were elucidated by extensive spectroscopic analysis, CD method, and by comparison with known analogs. Six of the alkaloids isolated displayed moderate activities against lipopolysaccharide (LPS)-induced pro-inflammatory factors in BV2 macrophages with IC50 values of 4.23–49.03 μM.

DDQ-mediated Direct Intramolecular-Dehydrogenative-Coupling (IDC): Expeditious Approach to the Tetracyclic Core of Ergot Alkaloids

An efficient route to 2-oxindoles bearing an all-carbon quaternary center at the pseudobenzylic position has been developed via a DDQ-mediated Intramolecular-Dehydrogenative-Coupling (IDC). The methodology involves a one-pot C-alkylation of β-N-arylamido esters (7) concomitant with dehydrogenative-coupling in the presence of stoichiometric amount of DDQ. A tentative mechanistic route has been proposed for the oxidative coupling. The methodology provides a two-step entry to the ergoline structure of ergot alkaloids.

Structure of Novel Alkaloids from Sceletium tortuosum

Sceletium tortuosum, family Mesembryanthemaceae, is a succulent plant native to South Africa where it is locally known as “Kanna”, “Channa”, or “Kougoed” [1]. The genus Sceletium has been used for anti-anxiety, anti-stress, and anti-depression in traditional medicine in South Africa [2]. Its psychoactive properties are due to the presence of Sceletium alkaloids (mesembrine and mesembrenone are major constituents, Figure) [3, 4]. Mesembrine was shown to have significant serotonin-uptake inhibitory activity [5]. This study reports on the isolation of two new alkaloids along with known compounds from the aerial part of S. tortuosum. Their structures were elucidated through spectroscopic methods, including 1D and 2D NMR experiments and HR MS analysis.

Characterization of protoberberine alkaloids in Coptidis Rhizoma (Huanglian) by HPLC with ESI‐MS/MS

This study aims to qualitatively analyze protoberberine alkaloids in crude extract of Coptidis Rhizoma using HPLC with ESI-MS/MS. Possible specific molecular weights of protoberberine alkaloids were firstly deduced according to literatures and were adopted to screen the alkaloids in the HPLC with ESI-MS of crude extract of Coptidis Rhizoma. As a result, 21 protoberberine alkaloids were found, including compounds of very low concentration and compounds coeluted in one peak. Among these, two compounds were positively identified and verified by comparison with standards. Ten of these compounds were first reported in this study for Coptidis Rhizoma. In addition, chromatographic retention parameters a and c of all compounds were obtained using their retention times under five gradient conditions and were applied to confirm the deduction about the structures of protoberberine alkaloids by tandem mass data.

PREPARATIVE SEPARATION OF TERTIARY ALKALOIDS FROM CORYDALIS YANHUSUO W. T. WANG BY pH-ZONE-REFINING COUNTER-CURRENT CHROMATOGRAPHY

Preparative separation of alkaloids from the crude extract of Corydalis yanhusuo by pH-zone-refining counter-current chromatography was successfully performed, The method used a biphasic solvent system composed of methyl-tert-butyl ether-acetonitrile-water (2:2:3, v/v), in which the organic phase containing 10 mM of triethylamine was used as a retainer in the stationary phase, while the aqueous phase containing 5 mM of hydrochloric acid as an eluter was used as the mobile phase. In the present study, 80 mg of glaucine, 41 mg of tetrahydropalmatine, and 67 mg of corydaline were separated from 1.16 g of the crude sample of C. yanhusuo with purity of 91.4%, 84.3%, and 98.2%, respectively. The structures of alkaloids were identified by 1H NMR and 13C NMR.

Practical, highly stereoselective allyl- and crotylsilylation of aldehydes catalyzed by readily available Cinchona alkaloid amide

We have demonstrated that bidentate Lewis base catalysts can be constructed based on the Cinchona alkaloid structure that promote highly stereoselective reactions of allyl- and crotyltrichlorosilane with aromatic as well as aliphatic aldehydes (90–99% ee, >98% diastereoselectivity). The catalysts are available in a one-pot procedure in >70% yield from cheap starting materials and promote the allylation reactions at ambient temperature. Gram scale reactions with catalyst recovery and reuse showcased the practicality of the catalytic system.

Synthesis of fluorinated catharanthine analogues and investigation of their biomimetic coupling with vindoline

The syntheses of 20,20-difluorocatharanthine and congeners, starting from the naturally occurring catharanthine, are reported. The fluorinated catharanthine analogues were investigated as potential precursors to dimeric Vinca alkaloids of the vinflunine family. However, the biomimetic coupling of the fluorinated catharanthine derivatives with vindoline led to unexpected alkaloid structures, the formation of which was rationalized.

New antiplasmodial alkaloids from Stephania rotunda

Ethnopharmacological relevanceStephania rotunda Lour. (Menispermaceae) is a creeper growing in many countries of Asia and commonly found in the mountainous areas of Cambodia. As a folk medicine, it has been mainly used for the treatment of fever and malaria. The pharmacological activity is mostly due to alkaloids. Thus the aim of this study is to isolate new bioactive alkaloids from Stephania rotunda and to evaluate their in vitro antiplasmodial activity. Materials and methodsAlkaloids were isolated and identified from dichloromethane and aqueous extracts using a combination of flash chromatography, high performance liquid chromatography, mass spectrometry and nuclear magnetic resonance. The purified compounds were tested for in vitro antiplasmodial activity on chloroquine-resistant W2 strain of Plasmodium falciparum. ResultsA new aporphine alkaloid named vireakine (2) along with two known alkaloids stephanine (1) and pseudopalmatine (8), described for the first time in Stephania rotunda, and together five known alkaloids tetrahydropalmatine (3), xylopinine (4), roemerine (5), cepharanthine (6) and palmatine (7) were isolated and identified. The structure of the new alkaloid was established on the basis of 1D and 2D NMR experiments and mass spectrometry. The compounds were evaluated for their in vitro antiplasmodial and cytotoxic activities. All tested compounds showed significant antiplasmodial activities with IC50 ranged from 1.2μM to 52.3μM with a good selectivity index for pseudopalmatine with IC50 of 2.8μM against W2 strain of Plasmodium falciparum and IC50>25μM on K562S cells. ConclusionsThis study provides evidence to support the use of Stephania rotunda for the treatment of malaria and/or fever by the healers. Alkaloids of the tuber exhibited antiplasmodial activity and particularly cepharanthine and pseudopalmatine.

A New Monoterpenoid Oxindole Alkaloid from Hamelia Patens Micropropagated Plantlets

Chemical studies on Hamelia patens (Rubiaceae) micropropagated plantlets allowed production of a new monoterpenoid oxindole alkaloid, named (-)-hameline (7), together with eight known alkaloids, tetrahydroalstonine (1), aricine (2), pteropodine (3), isopteropodine (4), uncarine F (5), speciophylline (6), palmirine (8), and rumberine (9). The structure of the new alkaloid was assigned on the basis of 1D and 2D NMR spectroscopy, mass spectrometry, and molecular modeling.