Concerning the alkaloid eripine from Hunteria umbellata

Eripine, a new indole alkaloid, was isolated from the leaves of Hunteria umbellata. The spectral data of the alkaloid, of eripinic acid and the O-acetyl and 19, 20-dihydro derivatives of the alkaloid led to the structure II. Heating of II gave a mixture (ratio 3,5:1) of the known alkaloid erinine (I) and its stereoisomer, isoerinine (VII), which is not found in nature. The same mixture was obtained on heating either erinine or isoerinine.     

Alkaloid production by callous tissue cultures of Cereus peruvianus (Cactaceae)

The morphologically undifferentiated cells of nonregenerant callous tissue of Cereus peruvianus cultured in the original medium and in medium supplemented with tyrosine were used as an alkaloid source. Comparison of alkaloid production by C. peruvianus plants and by callous tissues indicated that alkaloid levels were almost twice as high in callous tissues as in shoots of C. peruvianus plants. The ratio of alkaloid concentration between mature plant and morphologically und ifferentiated cells of callous tissue was 1∶1.7. A relationship between culture medium containing tyrosine and alkaloid production was also observed in the callous tissues of C. peruvianus. Since increased alkaloid production may be induced by additional factors such as tyrosine, increasing levels of tyrosine or other conditions of the culture medium may be considered factors for inducing higher alkaloid production by C. peruvianus callous tissues.     

Isolation and elucidation of the structure of homocryptolepinone

The structure of a new indolobenzazepine alkaloid, homocryptolepinone, isolated from extracts of the roots of the indigenous Ghanaian medicinal plant Cryptolepis sanguinolenta, is reported. The structure was determined using mass spectrometric, one-dimensional nOe difference nmr, and inverse-detected two-dimensional nmr experiments which included HMQC, IDR-(Inverted Direct Response)-HMQC-TOCSY, and HMBC experiments. The structure of homocryptolepinone is significant in that it may provide insight into the biogenesis of the benzpyrrolizinobenzazepine portion of the structure of the complex spiro nona-cyclic alkaloid cryptospirolepine previously isolated in these laboratories from C. sanguinolenta, and which has no precedent in alkaloid chemistry.     

A new norditerpenoid alkaloid acsonine from the roots of Aconitum kusnezoffii Reichb.

The known norditerpenoid alkaloid mesaconitine and a new alkaloid acsonine 1 were isolated from the roots of Aconitum kusnezoffii Reichb. The structure of 1 was established based on spectroscopic data.     

On the constitution of the macralstonidines

The alkaloid macralstonidine, which was originally isolated from Alstonia macrophylla WALL . by T. M. SHARP in 1934, has the molecular formula C₄₁H₄₈O₃N₄. The hydrolysis of this dimeric alkaloid yielded the macroline derivative 5 , N_(a)-methyl-sarpagine ( 6 ) and formaldehyde. Partial acid cleavage under deuterating conditions gave 5 -d₉, 6 -d₃ and decadeuterated macralstonidine. On the basis of spectral data, particularly an analysis of the mass spectra of macralstonidine and its decadeutero derivative, structure 2 has been elucidated for this alkaloid.     

Verbascenin,ein macrocyclisches Spermin-Alkaloid aus verbascum 184. Mitteilung über organische Naturstoffe

Verbascenine, a Macrocyclic Spermine Alkaloid Isolated from Verbascum The new spermine alkaloid verbascenine ( 1 ) has been isolated from extracts of the aerial parts of Verbascum phoeniceum L. and V nigrum L. The structure of the alkaloid was elucidated by chemical degradation and by a study of the spectral properties of the alkaloid and its derivatives. Compared to the 13-membered alter native 7 the 17-membered structure 1 is preferred on the basis of mass spectral arguments.     

Synthesis of the alkaloid thalactamine and a new synthesis for the alkaloid N-methyl-6,7-dimethoxy-1(2H)isoquinolone

The alkaloid thalactamine (N-methyl-5,6,7-trimethoxy-1(2H)isoquinolone) was synthesised in two steps from 4,5,6-trimethoxyhomophthalic acid (1a). Heating la with DMF/POCI₃ at 100° furnished thalactamine-4-earhoxylic acid which was easily decarboxylated to give the alkaloid thalactamine. By the same two steps, the alkaloid N-methyl-6,7-dimethoxy-1(2H)-isoquinolone is obtained from 4,5-dimethoxyhomophthalic acid. Synthesis for la from 2-bromogallic acid trimethyl ether was modified to give excellent yield. 5,6,7-Trimethoxy and 6,7-dimethoxyisocoumarin-4-carboxylic acid esters were synthesised from the homophthalic acids 1a and b by interacting them with DMF/phosphoryl chloride at 0°, to give corresponding 4-(N,N-dimethylaminoformylidene)isochroman-1,3-dione derivatives Vla and b and treating their alcoholic solutions with dry hydrogen chloride gas. The isocoumarins were converted into N-methyl-1(2H)isoquinolonesby treating them with aqueous methylamine. The isochromandione Vla slowly changed into 3-chloro-4-formyl-5,6,7-trimethoxyisocoumarin during the working up of the reaction.     

Disproof of the Overall Enzymatic Biosynthesis of Vindoline from Tryptamine and Secologanin by Cell-Free Extracts from the Leaves of Catharanthus roseus (L.) G. DON

A cell-free extract, which was isolated from the leaves of mature Catharanthus roseus plants by a previously published procedure, does not convert a mixture of secologanin and radiolabelled tryptamine to vindoline, as was recently claimed. The radioactivity in the purified alkaloid extract determined by earlier workers is certainly due to ‘impurities’ in the presumed ‘vindoline’. This was shown by extensive purification of the alkaloid extract (which contained added unlabelled vindoline as a carrier) followed by chemical conversion of vindoline to two derivatives and subsequent purification, ultimately giving unlabelled deacetylvindoline.     

Total Syntheses of the Alkaloids Ipalbidinium and Clathryimine B

 The indolizidinium alkaloid ipalbidinium and the quinolizidinium alkaloid clathryimine B were prepared starting from brominated 2-aminopyridines using two Pd-catalyzed cross-coupling reactions and a Sandmeyer-type diazotation/iodination protocol as the key steps.     

Hypepontine,a new quaternary alkaloid with antimicrobial properties

Abstract

New isoquinoline alkaloid hypepontine (1) together with a five known compounds, were identified in Hypecoum ponticum Velen, the partial synonym of Hypecoum procumbens L. The structure of the new substance was elucidated based on spectroscopic evidence. The tertiary and quaternary alkaloid mixtures as well as the isolated alkaloids were evaluated for their antibacterial and antifungal activity. The result revealed that the crude alkaloid mixture containing quaternary isoquinoline alkaloids showed potent antifungal and antibacterial activity.     

New Homoaporphine Base from Merendera robusta

The alkaloid composition of the bulb casing of Merendera robusta Bge. (Liliaceae) was investigated. The tropolone alkaloid colchicine was identified. A new homoaporphine base for which the structure methylmerenderine hydroxide was established by spectral and chemical methods was isolated.     

The Alkaloid of Cananga Odorata (I), Isolation of A New Base,Ushinsunine N-Oxide

A new aporphine alkaloid was isolated from the stem bark of Cananga odorata Hook. f. et Thomson (Annonaceae). The structure of this alkaloid has been established as ushinsunine N-oxide (6aS, 7R) ( 1 ) on the basis of spectroscopic evidences and by chemical transformation.     

Alkaloids from Plants of the Nitraria Genus. Structure of Sibiridine

The new alkaloid sibiridine was isolated from the aerial parts of Nitraria sibirica and N. schoberi. Its structure was established using spectral data and chemical transformations. Its synthesis was carried out.     

Xylogranatinin,a new pyrido[1, 2-<Emphasis Type="Italic">a</Emphasis>]pyrazine alkaloid from the fruit of a Chinese mangrove <Emphasis Type="Italic">Xylocarpus granatum</Emphasis>

9-Hydroxy-3-methoxy-6H-pyrido[1,2-a]pyrazin-6-one, a new pyrido[1,2-a]pyrazine alkaloid named xylogranatinin, was isolated from the fruit of a Chinese mangrove Xylocarpus granatum. Its structure was elucidated on the basis of spectroscopic data, especially 2D NMR techniques including HSQC and HMBC. To the best of our knowledge, this is the first time that a pyrido[1,2-a]pyrazine alkaloid was found as a natural product. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 351–352, July–August, 2007.     

Isolation of some quaternary alkaloids from the extract of roots ofChelidonium Majus L. by column and thin-layer chromatography

Summary A chromatographic system comprising untreated silica gel and an aqueous buffer—methanol eluent was investigated for the micropreparative separation of the alkaloids ofChelidonium majus L. The relationship between the logarithm of the retention factorsk of the alkaloids and volume fraction of methanol at pH^* 6 was linear for volume fractions in the range of 0.1 to 0.4. From this relationship it is possible to estimate the value of the retention factor for a given alkaloid in pure buffer and then the maximum volume of alkaloid extract that can be sampled on micropreparative column filled with silica gel.     

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.     

Argininosecologanin,a secoiridoid-derived guanidine alkaloid from the roots of Lonicera insularis

A new secoiridoid-derived guanidine alkaloid, argininosecologanin (1), along with 12 known iridoids and secoiridoids (2–13), was isolated from the roots of Lonicera insularis. The structures of the isolated compounds were established by the spectroscopic analysis and comparison of their spectral data with previously reported data. Compound 1 was assigned as the first secoiridoid-derived guanidine alkaloid isolated as a natural product. A plausible biogenetic pathway for 1 is suggested based on its structural similarity to (E)-aldosecologanin (4).     

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.     

Concerning Papaver bracteatum Lindl. On the structure of the Alkaloids E

From Papaver bracteatum LINDL . «Halle III» a new alkaloid representing the rhoeadine type has been isolated, the structure of which was elucidated by means of high resolution mass spectrometry and NMR. spectroscopy mainly.     

Elucidation of the structure of quindolinone,a minor alkaloid of cryptolepis sanguinolenta: Submilligram 1H-13c and 1H-15N heteronuclear shift correlation experiments using micro inverse-detection

Elucidation of minor natural product structures has been significantly augmented by inverse-detection; further improvement has been afforded by the development of micro inverse-detection probes. We report here the elucidation of the structure of a new alkaloid, quindolinone (5H, 10H-indolo[3,2-b]quinolin-11-one), from the West African plant Cryptolepis sanguinolenta. All nmr data for this minor, preparative hplc-isolated alkaloid, including ¹H-¹⁵N one? bond heteronuclear shift correlation (HMQC) data, were recorded on an 800 μg sample of the alkaloid dissolved in 140 μl of 100% d₆-DMSO using a 400 MHz spectrometer.