Antimicrobially active alkaloids from Tabernaemontana pachysiphon

Twenty-three alkaloids and five steroids and triterpenes have been isolated and identified from the root bark and stem bark of a Nigerian Tabernaemontana pachysiphon. The following bases have not previously been obtained from this species: isositsirikine, 16-epiisositsirikine, normacusine B, 16-epiaffinine, anhydrovobasindiol, tubotaiwine, ibogaline, isovoacangine, voacamine, lochnericine, 3R-hydroxyconopharyngine, 3S-hydroxyconopharyngine and 11-demethylconoduramine, the last three being new alkaloids. The dimeric indole alkaloids and 3R/S-hydroxyconopharyngine were shown to possess strong antibacterial activity against Gram-positive bacteria and the dimers against Gram-negative bacteria also.     

Catharinensine,an oxindole alkaloid from Peschiera catharinensis

The structure of catharinensine isolated from Peschiera catharinensis was deduced from a detailed analysis of its ¹H NMR, ¹³C NMR and mass spectra. The synthesis of 17-demethoxyrhynchophylline confirmed its structure, and led us to suggest the configuration allo A for catharinensine. Coronaridine, isovoacangine, heyneanine, 16-epiaffinine, decarbomethoxyvoacamine and conodurine were also isolated.     

Morphinan alkaloids in Papaver bracteatum: Biosynthesis and fate

The known metabolic pathway for hydrophenanthrene alkaloids in Papaver somniferum has been examined for occurrence in P. bracteatum, a species reported to contain thebaine but no codeine or morphine. 1,2-Dehydro-reticulinium-[3-¹⁴C] chloride and (±)-reticuline-[3-¹⁴C] were fed to P. bracteatum plants and both were incorporated, the former into reticuline and thebaine and the latter into thebaine, suggesting that thebaine biosynthesis is the same in the two species. Studies of the natural abundance of morphinan alkaloids in P. bracteatum and the results from feeding codeinone-[16-³H] and codeine-[16-³H] indicate that this species can reduce codeinone to codeine but can not perform either of the demethylations to produce codeinone or morphine. Fed thebaine-[16-³H] was substantially metabolized but not by pathways that involved demethylations to either oripavine or northebaine.     

Alkaloids and olefinic acids from Cryptocarya amygdalina

From the bark of Cryptocarya amygdalina two new olefinic acids with a tetracyclo(4.3.0^2.4.0^3.7) non-8-enemoiety are reported. From the same source the benzylisoquinoline alkaloids orientaline and laudanidine are also reported.     

1H NMR Spectroscopy of pyrrolizidine alkaloids

The ¹H NMR spectra of three pyrrolizidine alkaloids of the macrocyclic diester type, retrorsine, seneciphylline and senecionine, plus their three N-oxides have been assigned. Previous ¹H NMR studies of these pyrrolizidine alkaloids have stressed the difficulties of spectral intrepretation. The results reported here will provide a useful resource for analysis of tertiary structure in these and related compounds.     

Seco-tabersonine alkaloids from Tabernaemontana corymbosa

Two seco-tabersonine alkaloids, jerantiphyllines A and B, in addition to a tabersonine hydroxyindolenine, jerantinine H, and a recently reported vincamine alkaloid 7, were isolated from the leaf extract of the Malayan Tabernaemontana corymbosa and the structures were established using NMR and MS analysis. Biomimetic conversion of jerantinines A and E to their respective vincamine and 16-epivincamine derivatives were also carried out.     

Alcaloïdes des ecorces de racines de Crioceras dipladeniiflorus

Eight alkaloids have been isolated from the root bark of Crioceras dipladeniiflorus. Five of them are new: Δ¹⁴-vincamine (I) epi-16 Δ¹⁴-vincamine (II) 12-methoxy-δ ¹⁴-vincamine (V) apo Δ¹⁴- vincamine (VI), and ditabersonine (VII), a dimeric alkaloid; the three others are known, voaphylline (III), tabersonine, (IV), and vobtusine (VIII).     

Biosynthese und Stoffwechsel der chinolizidinalkaloide von Sophora alopecuroides

Administration of matrine-U-³H and sophocarpine-U-³H to Sophora alopecuroides seedlings shows that these compounds were incorporated into quinolizidine alkaloids such as matrine, sophacarpine, and their N-oxides, but not into sophoridine. It is suggested that there is no stereochemical conversion of alkaloids of matrine configuration into sophoridine by the plant. The incorporation of cadaverine-1,5-¹⁴C was so low that it cannot be regarded with certainty as a physiological precursor of the alkaloids. The N-oxides of matrine and sophocarpine were isolated and identified by their chromatographic and chemical properties.     

Chemical constituents from the aerial parts of Meconopsis horridula (Papaveraceae)

Chemical investigation of the aerial parts of Meconopsis horridula led to the isolation and structural identification of nine flavonoids, two alkaloids and five terpenoids. Their structures were determined by comparison of ¹H and ¹³C NMR data with those reported in literature. The discovery of alkaloid cavidilinine (11) and two pentacyclic triterpenoids (15 and 16) from M. horridula provides evidence to support the view that Fumarioideae and Papaveroideae should be combined into a single family Papaveraceae.     

The sequential appearance and metabolism of alkaloids in Heimia salicifolia

The seeds of Heimia salicifolia do not contain alkaloids. Two unidentified alkaloids were detected in 1-week-old seedlings; these alkaloids were absent from older plant samples. Lyfoline, cryogenine, and lythrine were first detected in 2-week-old plants. Sinicuichine was first observed in 3-week-old plants and nesodine in 2-month-old plants. The maximum rates of synthesis for most of these alkaloids occurred in 1- to 2-month-old plants. Following administration of ¹⁴CO₂ to H. salicifolia plants, small quantities of alkaloids were purified to constant specific activity without alkaloid dilution; 95.6% of the administered ¹⁴CO₂ was assimilated and up to 0.16% of this activity was incorporated into known alkaloids. Sinicuichine and lyfoline were shown to undergo catabolism, while cryogenine was degraded very slowly, if at all. Evidence is presented for the conversion of lyfoline to lythrine.     

Polyavolinamide,an indolosesquiterpene alkaloid from Polyathia suaveolens

A new indolosesquiterpene alkaloid, polyavolinamide, has been identified in the stem of Polyathia suaveolens accompanied by the three previously isolated indolosesquiterpene alkaloids, polyavolensin, polyavolensinol, polyavolensinone, as well as an unidentified triterpene and an aporhine alkaloids. Polyavolinamide was also the major component of the root bark. Its structure was assigned on the basis of ¹¹H and ¹³C NMR, and mass spectrometry.     

Alkaloids of Alstonia macrophylla

A new alkaloid, 19-hydroxyvincamajine, has been isolated from the leaves of Alstonia macrophylla. In addition to this, eight other indole alkaloids, alstonerine, alstophylline, macralstonine, anhydromacralstonine, talcarpine, vincamajine, vincorine and cabucraline, were also isolated and identified from the bark and leaves of A. macrophylla of Sri Lanka. The last five alkaloids have been isolated for the first time from this species and the ¹³NMR of alstonerine and alstophylline are reported.     

Minor alkaloids of Heliotropium curassavicum

Isolation and structure determination of the minor alkaloids of Heliotropium curassavicum are described. These include the new pyrrolizidine alkaloids, heliocurassavine [isoretronecanol (?) curassavine], heliocoromandaline [isoretronecanol (+) viridiflorate], heliocurassavicine [isoretronecanol (?) trachelanthate], heliocurassavinine [laburnine (?) trachelanthate], curassavinine [supinidine (?) curassavate], coromandalinine [supinidine (+) viridifloratel, heliovinine [supinidine (?) trachelanthate] and curassanecine [1-(α-hydroxy-methyl)-8α pyrrolizidin-1β-ol]. Structures were established by high resolution ¹H NMR, mass spectrometry and paper electrophoresis of the alkaloids and their hydrolysis products.     

Alkaloids of Pterotaberna inconspicua

Sixteen alkaloids were isolated from the seeds and root-bark of Pterotaberna inconspicua, collected in Zaïre. They were voacangine 3-carbonitrile, voacangine, voacristine, 3,6-oxido-voacangine, vobasine, 10-hydroxycoronaridine, 10-hydroxyheyneanine, methuenine, apparicine, tubotaiwine, 16-epi-isositsirikine, 16-epimethuenine, 3,14-dihydroellipticine, an isomer of corynantheol, 16-epimethuenine N-oxide and tetra-hydroellipticine.     

Biosynthesis of pyridine alkaloids from Tripterygium wilfordii

Nicotinic acid-6-¹⁴C and nicotinamide adenine dinucleotide-carbonyl-¹⁴C were rapidly metabolized in T. wilfordii Hook. with formation of all compounds in the pyridine nucleotide cycle. Nicotinic acid-6-¹⁴C and the nicotinamide moiety of NAD were efficiently incorporated into wilfordic acid and hydroxywilfordic acid, the pyridinium moieties of the ester alkaloids. The structures of wilfordic acid and hydroxywilfordic acid were confirmed using GLC-MS. The molecular formulae of the four isolated alkaloids were determined by high resolution MS and agreed with earlier results based on elemental analysis.     

Alkaloids of Fumaria vaillantii

The aerial parts of Turkish Fumaria vaillantii yielded 26 isoquinoline alkaloids. Of these, oxysanguinarine, (±)-8-acetonyldihydrosanguinarine, (±)-8-methoxydihydrosanguinarine and fumaramidine are reported for the first time from this plant. New alkaloids for the genus Fumaria are dihydrosanguinarine, norsanguinarine, (+)-isocorydine, (?)-corledine and (+)-juziphine. This is the first occurrence of the isoquinolone N-methylcorydaldine in a member of the Fumariaceae. Spectral data are given for the new compound, E-fumaramine.     

Chemical constituents of Melodinus hemsleyanus diels

Phytochemical investigation on the aerial parts of Melodinus hemsleyanus diels (Jahrb, Syst, 1995) led to the isolation and identification of 27 compounds, including fifteen aspidosperma-type alkaloids (1–15), four quinoline-type alkaloids (16–19), three quebrachamine-type alkaloids (20–22), and five eburna-type alkaloids (23–27). The structure of compound 1 was elucidated by means of spectroscopic analysis, including HRESIMS, and 1D and 2D NMR experiments. Compounds 1–2, 6, 10, 12, 13, 15, 16 and 20–27 are herein reported for the first time from the studied plant, while the compounds 1–2 and 21 have not previously been recorded in the genus Melodinus. The aspidosperma-type monoterpenoid indole alkaloids in M. hemsleyanus could serve as chemotaxonomic markers.     

13C NMR spectroscopy of Pyrrolizidine alkaloids

The ¹³C NMR spectra of nine pyrrolizidine alkaloids of the macrocyclic diester type, seven of the corresponding N-oxides and of the parent base retronecine have been recorded and the signals assigned. The 13C NMR signals were found to be sensitive to structural variation in both the diester moiety and the heterocyclic ring system, providing useful information for structural elucidation, particularly when the ¹H NMR spectra may be difficult to interpret.     

Incorporation of cinnamic acid-2-[14C] into tylophorine

Tylophora indica plants have been shown to contain phenanthroindolizidine alkaloids of the tylophorine type. Cinnamic acid-[2-¹⁴C]was incorporated efficiently into these alkaloids supporting the hypothesis that ring A and C-10 and C-6$\text{\$}\text{?}$of tylophorine are derived from phenylalanine.     

16-epi-19-S-vindolinine,an indoline alkaloid from Catharanthus roseus

Studies on the alkaloids of Catharanthus roseus have resulted in the isolation of a new alkaloid, to which the structure of 16-epi-19-S-vindolinine has been assigned.