New quinoline alkaloids

The new quinoline alkaloid sarcomejine (100) was isolated from the bark of Sarcomdicope megistophyUa by Fokialakis et al. [115] The skeletal framework was assembled from NM R and mass spectrometric data, necessitating the authors to then differentiate between two alternative structures on the basis of a 5 Hz optimized long-range GHMBC spectrum. Correlations from the proton at the 8 position of... 

A1-Khalil S, Alkofahi A, et al. Transtorine, a new quinoline alkaloid from Ephedra transitoria. J Nat Prod 1998 61 262-3. 

Isolation and Detection.—The isolation of new quinoline alkaloids and of alkaloids of established structure that have been obtained from new sources is recorded in the Table.Thin-layer chromatography is employed increasingly to recognize the presence of known quinoline alkaloids, and a useful account of the application of the method to a large group of quinoline alkaloids is now available. Gas-liquid chromatography was introduced for the detection and estimation of quinoline alkaloids and was applied to the analysis of basic extracts of Skimmia species and of Otoisya ternata. A bisexual Skimmia hybrid contains skimmianine (1 = H, =... 

Up to the middle of this century quinine (1) was used for the treatment of malaria, and with the widespread development of chloroquine-resistant strains of Plasmodium falciparum it has become important again. Quinine has been used for the treatment of malaria for more than 350 years and has its origin in Peru in the early 17th century. Quinine was the lead structure in the discovery of new synthetic derivatives like mefloquine that have higher antimalarial activity. This section will focus on other new quinoline alkaloids. The mechanism of antiplasmodial action and resistance of quinolines is well described elsewhere [116]. 

In the ten years since quinoline alkaloids were last reviewed by Open-shaw in Volume IX of this treatise, the constituents of a considerable number of rutaceous species have been studied for the first time and more than 70 new quinoline alkaloids have been isolated. The most notable structural work includes the study of the phenolic alkaloids of the dihy-drofuro- and dihydropyranoquinoline group found in Balfourodertdron and... 

Abe and Taylor isolated a new quinoline alkaloid, Cl7Hi9N04, named oricine, from timber of the West African tree Oricia suaveolens (Engl.) Verdoon. The UV, IR, and NMR spectra (Scheme 1, Section I) indicated that oricine was 6,7-dimethoxy-N-methylflindersine (144), and this was confirmed by synthesis (88). 

Kudo Y, Kato H, Rotinsulu H, Losung F, Mangindaan REP, de Voogd NJ, et al. Aap-toline A, a new quinoline alkaloid from the marine sponge Aaptos suberitoides. Heterocycles 2014 88(l) 591-4. 

Another Rutaceous plant with a similar alkaloidal spectrum to rue is prickly ash bark—Zanthoxylum spp. Two new quinoline alkaloids isolated from Zanthoxylum simulans were shown to have cytotoxic and antiplatelet activities (Chen et al. 1994). 

Rahman AU, Khalid A, Sultana N, et al., New natural cholinesterase inhibiting and calcium channel blocking quinoline alkaloids, Inhibition Med Chem 21 703-710, 2006. 

In addition to quinoline alkaloids (see Table 1), Glycosmis mauritiana contains 5-hydroxy-2,3-dimethoxy-A7-methylacridone (arborinine) and a new prenyl-acridone (28).4 The structure of the latter alkaloid was indicated by spectroscopy, by the presence of a peri-hydroxyl group, and by heating it with formic acid to give the cyclization product (29), thus showing that the prenyl group was at C-2, i.e. adjacent to the hydroxyl group, rather than at C-4. An unexpected by-product of the reaction with formic acid was the acridone (22). 

Only six new alkaloids of these groups have been obtained this year, but there has been considerable emphasis on synthesis within all three groups. A useful review of the synthesis of quinoline alkaloids has been published.1... 

Isolation and Spectroscopic Studies.—The Table (p. 79) records the isolation of new alkaloids and of alkaloids of established constitution obtained from new sources.2-16 The further investigation of Haplophyllum perforatum raises to nineteen the number of quinoline alkaloids found in this species. Another feature of isolation studies this year is the examination of four species of Myrtopsis. 

Hydroxy-l-methyl-3-prenyl-2-quinolones, cf. (22), are key intermediates in the synthesis of quinoline alkaloids, and usually are prepared in one stage from an N-methyl-aniline and diethyl prenylmalonate. Interesting new methods beginning with N-methylisatoic anhydrides, cf. (20), have been explored and briefly repor-... 

The Okinawan ascidian Lissodinum sp. produces the cytotoxic diterpene alkaloids haterumaimides J (99) and K (100) [86[. The incredibly prolific cyanobacterium Lyngbya majuscula has furnished the quinoline alkaloid 101 [87[. The new quinolones 102 and 103 were isolated from the sponge Hyrtios erecta [26[. 

Foumet A, Vagneur B, Richomme P, Bruneton J (1989) New 2-aryl and 2-alkyl quinoline alkaloids isolated from Bolivian Rutaceae Galipea longiflora. Can J Chem 67 2116-2118... 

Stenberg VI, Travecedo EF, Musa WE. A new photoreduction on quinoline alkaloids. Tetrahedron Lett 1969 25 2031-2033. 

Ptelea trifoliata has star qualities in its production of quinoline alkaloids and the work of Mitscher and Reisch and their respective collaborators published during the year has added eight new alkaloids to the long list of quinolines already identified as constituents of this species. Other notable events include the isolation of araliopsine (48), the first angular hydroxyisopropyldihydrofuroquinoline alkaloid," and the identification of two alkaloids with unique structures, perfamine (11) from a Hap-lophyllum species and melochinone (2) from a member of the Sterculiaceae. ... 

A considerable number of new quinoline and acridone alkaloids has been identified and the recognition of two new groups of dimeric quinolinone alkaloids is of particular interest. There has been little activity in the quinazoline alkaloid area and this section is omitted this year. 

Quinoline Alkaloids withont 3-Substitnents.—4-Quinolones with a long-chain alkyl group in the 2-position were obtained originally from fungi, but in recent years have been shown to be present in some higher plants. A new alkaloid, 2-(n-undecyl)-4-quinolone (5 n = 10), has now been isolated from Ptelea trifoliata and its structure established by spectral data. The roots of Ruta graveolens contain an unresolved mixture of alkylquinolones (5 n = 10—13). ... 

Ruta species, and the identification from a Ptelea species of a new group of quinoline alkaloids containing a terminal double bond in the prenyl portion of the molecule. New types of quinoline alkaloids are represented by the... 

The application of spectroscopic methods for the elucidation of the structures of quinoline alkaloids has developed to the point where the constitutions of many new alkaloids have been established solely by UV, IR, NMR, and mass spectrometry. The NMR spectra of quinoline alkaloids have been discussed (Volume IX of this treatise) (4, 5), and the application of mass spectrometry has also been reviewed (6). Schemes 1 and 22 summarize NMR data for a selection of typical quinoline alkaloids. In discussing structure work spectroscopic data will be given only when they are of special significance. 

During the last decade, new alkaloids of this type have been isolated, methods of asymmetric synthesis have been developed, the absolute stereochemistry of a number of alkaloids has been established, and the mechanisms of certain rearrangement reactions of furo- and pyrano-quinoline alkaloids of the group have been studied. Additional pyrano-quinolines of the flindersine type have been discovered, and new methods of synthesis have been developed. Isopropyldihydrofuroquinoline alkaloids without a hydroxy group in the side chain are characteristic components of Lunasia species, but not much new work on this group has appeared recently. 

As a result of the reported antimicrobial action of extracts of the hop tree, Ptelea trifoliata, Mitscher et al. (54) investigated the aboveground constituents and found that the sole active agent was a new phenolic quinolinium derivative pteleatinium salt. The alkaloid was isolated as the chloride, C16H20NO4CI, and was shown to be the 8-hydroxy-Af-methyl-platydesminium salt (38) on the basis of IR, UV, NMR, and mass spectrometry and of correlation with known quinoline alkaloids. Thus, pyridine effected demethylation to the 4-quinolone 39 which, with diazomethane, was converted into (+)-balfourodine (12), while methylation of pteleatinium chloride with methyl iodide and sodium carbonate gave O-methyl-... 

Non-hemiterpenoid Quinolines.—The three non-hemiterpenoid quinoline alkaloids reported this year are all 3-metho iyquinoline derivatives. Furoquinoline alkaloids had been isolated previously from Chloroxylon swietenia (East Indian satin wood), but now two new alkaloids, swietenidins A and B, have been obtained from the bark. Spectroscopic studies of swietenidin A and its monomethyl ether, and comparison of the data with those of the known 8-methoxy-iV-methyl-2-quinolone lunacridine, indicated that the alkaloid was the... 

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