Aristoserratin,ein neues Indolalkaloid aus Aristotelia serrata W.R.B. OLIVER und A. peduncularis (LABILL.) HOOK. F. 178. Mitteilung über organische Naturstoffe

Aristoserratine, a New Indole Alkaloid from Aristotelia serrata W.R.B. OLIVER and from A. peduncularis (LABILL .) HOOK . F. The new indole alkaloid aristoserratine (2) has been isolated from Aristotelia. Its structure and absolute configuration were elucidated on the basis of spectroscopic data.     

Sorellin und Hobartin,zwei neue Indolalkaloide aus Aristotelia peduncularis (LABILL.) HOOK. F. 173. Mitteilung über organische Naturstoffe

Sorelline and Hobartine, Two New Indole Alkaloids from Aristotelia peduncularis (LABILL .) HOOK . F. From Aristotelia peduncularis (LABILL .) HOOK . F. two new indole alkaloids, sorelline ( 1 ) and hobartine ( 2 ), have been isolated. Their structures were elucidated on the basis of spectroscopic data (the formulae represent their relative configurations). The alkaloids 1 and 2 have closely related structures with a monosubstituted indole moiety and an unrearranged monoterpene unit in the aliphatic part.     

The Structure of the Alkaloid Peduncularine. Communication no. 172 on organic natural products

The revised structure 1 is put forward for peduncularine, the main alkaloid of Aristotelia peduncularis (Labill.) HOOK. F. (Elaeocarpaceae), on the basis of its spectroscopic properties and those of its degradation products, the Hofmann base 3 and the hydrogenation product 4 . Structure 1 represents the relative configuration of the alkaloid. Peduncularine belongs to the class of indole alkaloids with a monoterpene unit as the aliphatic portion. To our knowledge it constitutes the first example in which an isopropyl group has become detached from the terpene unit and occurs as a substituent on nitrogen.     

A New Alkaloid from the Seeds of Sophora alopecuroides L.

Alopecurin A, an alkaloid with an unprecedented skeleton, was isolated from the seeds of Sophora alopecuroides L. The absolute configuration and structure of this compound was identified as (3S,12R)‐3‐hydroxy‐1,7‐diazatricyclo[10.4.0.1^3,7]heptadecane‐11,16,17‐trione (=(7S,15aR)‐decahydro‐7‐hydroxy‐6H‐7,11‐methano‐4H‐pyrido[1,2‐a][1,7]diazacyclododecine‐4,15,16(12H)‐trione). The structure and absolute configuration was elucidated by spectroscopic methods, mainly HR‐ESI‐TOF‐MS, IR, 1D‐NMR (¹H‐ and ¹³C‐NMR), 2D‐NMR (COSY, NOESY, HSQC, HMBC), and particularly X‐ray crystal‐diffraction and CD spectral analysis.     

Das Spermin-Alkaloid Chaenorpin

The Spermine Alkaloid Chaenorpine Chaenorpine ( 1 ) was isolated from Chaenorhinum minus (Scrophulariaceae). Its structure elucidation was achieved on the basis of chemical degradation and spectroscopic measurements in comparison to the known alkaloid chaenorhine ( 2 ). Structure 1 displays the absolute configuration.     

Die Struktur des Bisindolalkaloides Amatain ( = Grandifolin,Subsessilin)

The structure of the bisindole alkaloid amataine (= grandifoline, subsessiline) Amataine ( 1 ) was isolated from the roots of Hedranthera barteri (HOOK . F .) PICHON (Apocynaceae). In comparison to the alkaloid vobtusine ( 5 ), which was isolated from the same plant, 1 contains two hydrogen atoms less. By reduction of 1 with H₂/PtO₂ or with NaBH₄ dihydromataine ( = isovobtusine, 13 ) was formed which is isomeric to 5 . Acid catalysed water addition to 1 afforded hydratoamataine ( 15 ), which was reduced to 5 with NaBH₄. Thermolysis of 15 gave 1 . The difference between the two isomeric bases 5 and 13 has to be attributed to a different configuration at the spirocenter C(7). In contrast to 5 amataine ( 1 ) contains an ether bridge instead of a hydroxy group; this bridge is located between C (2′) and C (8).     

A novel norsesquiterpene alkaloid from the mushroom-forming fungus Flammulina velutipes

A new norsesquiterpe alkaloid（1） was isolated from the solid culture of mushroom-forming fungus Flammulina velutipes fermented on rice.The structure of 1 was elucidated by spectroscopic methods.The absolute configuration of C-1 in 1 was determined using the circular dichroism data of their [Rh₂（OCOCF₃）₄]complex.     

α‐Haloketal (1′R,4S,5S)‐dimethyl 2‐(1′‐bromoethyl)‐2‐(3,4‐dimethoxyphenyl)‐1,3‐dioxolane‐4,5‐dicarboxylate

The crystal structure and absolute configuration of the title compound, C₁₇H₂₁BrO₈, have been determined by X‐ray analysis. They confirmed the 1′R absolute configuration at the 1′‐bromoethyl moiety which has been assigned previously on the basis of chemical and spectroscopic data. Cohesion of the crystal can be attributed to weak intermolecular C—H?O and van der Waals interactions.     

Synthesis of Aristotelia-Type Alkaloids. Part XV. Total synthesis of (+)-hobartinol

Synthetic (+)-makomakine ( 6 ) was transformed in six steps into (+)-17R,18R)-17,18-dihydrohobartine-17,18-diol ((+)- 5 ) with an overall yield of 38% (Scheme 2). This compound was shown to be identical with natural hobartinol, a monoterpene indole alkaloid from Aristotelia australasica, originally believed to be the (17S)-epimer 1 . At the same time, the synthesis of (+)- 5 delineates the hitherto unknown absolute configuration of this metabolite.     

Secu'amamine A, a novel indolizidine alkaloid from Securinega suffruticosa var. amamiensis

A novel indolizidine alkaloid, secu'amamine A (1), was isolated from the leaves and twigs of the medicinal plant, Securinega suffruticosa var. amamiensis together with securinine (2). The structure and relative stereochemistry of 1 was elucidated by spectroscopic data and its absolute configuration was assigned on the basis of the OMe-madelate method.     

Hobartine: a tetracyclic indole alkaloid extracted from Aristotelia chilensis (maqui)

The natural compound hobartine {systematic name: (1R)‐3‐[(1S,5S)‐(4,4,8‐trimethylbicyclo[3.3.1]non‐7‐en‐2‐yl)methyl]‐2,3‐dihydro‐1H‐indole}, C₂₀H₂₆N₂, (I), is an indole alkaloid isolated from Aristotelia chilensis as part of a study of secondary metabolites from Chilean flora. The colourless compound has a tetracyclic structure closely related to the strongly coloured polymorphic structures discussed in Paz et al. [Acta Cryst. (2013), C 69 , 1509–1512] and Watson et al. [Acta Cryst. (1989), C 45 , 1322–1324]. The main differences reside in the absence of a keto group in (I) compared with the previous structures, as well as an endo double bond in (I) contrasting with the exo double bond found in the previous structures. The supramolecular structure of (I) in strongly related to the twofold screw axis, around which isolated chains build up, internally linked by an N—H...N hydrogen bond which is the only significant intermolecular interaction present in the structure.     

Macrocarpamin,ein neues Bisindolalkaloid aus Alstonia macrophylla WALL. 167. Mittelung über organische Naturstoffe

Macrocarpamine, a new bisindole alkaloid from Alstonia macrophylla WALL . A new bisindole alkaloid give the name (?)-macrocarpamine ( 3 ) was isolated from the bark of Alstonia macrophylla WALL . Under pyrolytic conditions 3 is cleaved into the two known bases (+)-pleiocarpamine ( 2 ) and (?)-anhydro macrosalhin-methin ( 5 ) (Scheme 1). The structure of 3 (including relative configuration) was deduced on the basis of chemical evidence and from its UV.-, IR.-, NMR.- and mass spectroscopic data.     

Benzodiazepine Alkaloids from Marine‐Derived Endophytic Fungus Aspergillus ochraceus

A new fungus‐derived benzodiazepine analogue, 2‐hydroxycircumdatin C ( 1 ), and a compound which has been isolated from a natural resource for the first time, but has been previously synthesized, namely (11aS)‐2,3‐dihydro‐7‐methoxy‐1H‐pyrrolo[2,1‐c][1,4]benzodiazepine‐5,11(10H,11aH)‐dione ( 2 ), along with five structurally related known alkaloids ( 3 – 7 ), were isolated from Aspergillus ochraceus, an endophytic fungus derived from the marine brown alga Sargassum kjellmanianum. Their structures were established on the basis of spectroscopic methods. The absolute configuration of 1 was determined through CD evidence. Compound 1 displayed significant DPPH radical‐scavenging activity with an IC₅₀ value of 9.9 μM , which is 8.9‐fold more potent than that of butylated hydroxytoluene (BHT), a well‐known synthetic positive control.     

Cyclohexadepsipeptides from the Filamentous Fungus Acremonium sp. BCC 2629

Seven new cyclohexadepsipeptides, beauvenniatins F, G₁, G₂, G₃, H₁, H₂, and H₃ ( 1 – 7 , resp.), were isolated from cultures of the fungus Acremonium sp. BCC 2629. Their structures were elucidated by extensive spectroscopic analyses. The absolute configurations were addressed by HPLC analyses of their acid hydrolysates. Their biological activities were evaluated against Mycobacterium tuberculosis H37Ra and Plasmodium falciparum K1; the respective MIC and IC₅₀ values were in the micromolar range.     

Isoquinoline alkaloids from Asimina triloba

A new aporphine glycoside, (-)-anolobine-9-O-β-D-glucopyranoside was isolated from the twigs of pawpaw (Asimina triloba) along with 7 known alkaloids including five aporphine alkaloids (anolobine, nornuciferine, norushinsunine, liriodenine, and lysicamine), a proaporhine alkaloid (stepharine), and a tetrahydrobenzylisoquinoline alkaloid (coclaurine). Among these compounds, nornuciferine, lysicamine, stepharine, and coclaurine are reported for the first time from this plant. The structure of the new compound was elucidated by spectroscopic methods, including 1?D, 2?D NMR, and HRESI-MS. The absolute configuration of compounds 1, 2, 7 and 8 was determined by CD experiment.     

Transformation of the Iboga alkaloid voacangine into voaketone, a derivative of beta-carboline (author's transl)]

Transformation of the Iboga alkaloid voacangine into voaketone, a derivative of β-carboline. The reduction product voacanginol ( 2 ), obtained from the indole alkaloid (?)-voacangine ( 1 ), gave, by treatment of its tosylate 3 with methanolic pyridine in the presence of air, the rearrangement product (?)- 5 (voaketone). Its structure was derived from spectroscopic evidence (mainly NMR. and mass spectra) and some chemical transformation reaction, especially deuterium labelling. A possible mechanism for the formation of 5 from 3 is given in Scheme 6. The absolute configuration of 5 was deduced by comparison with yohimbine derivatives.     

Meroterpenes from an algicolous strain of Penicillium echinulatum

One new meroterpene, arisugacin K (1), and four known ones, arisugacin J (2), arisugacin G (3), arisugacin C (4), and territrem C (5), were isolated from the culture of Penicillium echinulatum pt‐4, an endophytic fungus isolated from the marine red alga Chondrus ocellatus. The structure and the absolute configuration of 1 were unambiguously elucidated by spectroscopic analyses and quantum chemical calculations, which further resulted in the assignments of absolute configurations for the other arisugacins and territrems. Compound 1 showed inhibitory activity against Escherichia coli with an inhibition diameter 8 mm at 30 µg/disk and 4 exhibited lethality against Artemia salina with an LC₅₀ of 48.6 µg/ml. Copyright © 2014 John Wiley & Sons, Ltd.     

Alstonia scholaris: Struktur des Indolalkaloides Narelin

Alstonia scholaris: The structure of the indole alkaloid nareline Besides the known akuammidine, picralinal, picrinine and pseudoakuammigine a new indole alkaloid called nareline (M=352) was isolated from Alstonia scholaris R. BR. , which belongs to the plant family of Apocynaceae. Its structure 2 was deduced by single crystal X-ray diffraction. 2 represents the absolute configuration. The spectroscopic data of 2 and its derivatives (Scheme 1) as well as their chemical behavior support this structure. In biogenetic sense nareline is related to the bases akuammiline ( 4 ) and picraline ( 5 ) (Scheme 2). In contrast to those the C-atom 5 is exocyclic and represents an aldehyde group which forms together with the oxygen atom of the N (4)-hydroxylamine group a cyclic half acetale. - By oxidation (CrO₃/CH₃COOH) of 2 the oxindol derivative 19 (oxonareline) is formed which contains a cyclic acetal as a partial structure element (Scheme 4).     

Alkaloids of Arundo donax L. 13. The structure of a new dimeric indole alkaloid,arundanine

The structure of a new dimeric indole alkaloid, named arundanine, isolated from the roots of Arundo donax L. (Poaceae), was elucidated. Arundanine was identified as 3-(N,N-dimethylaminoethyl)-4-[3-(N,N-dimethylaminoethyl)indole-1-yl]-5-hydroxyindole on the basis of spectroscopic data and the transformation into the known alkaloid, arundamine.     

A New Glycine Derivative and a New Indole Alkaloid from the Fermentation Broth of the Plant Endophytic Fungus Pestalotiopsis podocarpi Isolated from the Chinese Podocarpaceae Plant Podocarpus macrophyllus

A new glycine derivative, podocarpiamide ( 1 ), a new indole alkaloid, 1‐methoxy‐1H‐indol‐3‐ethanol ( 2 ), together with two known compounds, 1‐methoxy‐1H‐indole‐3‐acetic acid ( 3 ) and methyl 1‐methoxy‐1H‐indole‐3‐acetate ( 4 ), were isolated from the fermentation broth of the plant endophytic fungus Pestalotiopsis podocarpi. Their structures were elucidated by extensive spectroscopic analysis including 1D‐ and 2D‐NMR (HSQC, HMBC, and COSY) and MS experiments. Compound 1 has an interesting unusual carbamic acid structure.