Alkaloids of the Compositae

The occurrence and distribution of pyrrolizidine alkaloids in members of the tribes Eupatorieae and Senecioneae have been reviewed. 

Yamada, H. Tatematsu, Y. Kyotani, Y. Hirata, M. Haga, and I. Hirono, Phytochemistry, 1978,17, 1667. 

Senampelines C (37) and D (38) have again been isolated, as a mixture, from Senecio mikanoides [Otto ex] Harv. ° In addition, three new senampelines, i.e. E (39), F (40), and G (41), were also present in this species, in the ratio 2 1 1. The structures of senampelines E—G were determined by H n.m.r. spectroscopy and by degradation by methoxide to the corresponding aldehyde esters (42). ° 

Bohlmann, C. Zdero, D. Berger, A. Suwita, P. Mahanta, and C. Jeffrey, Phytochemistry, 1979,18, 

Previous investigations of Tussilago farfara L. (coltsfoot) have yielded two macrocyclic pyrrolizidine alkaloids, senecionine and 

A new macrocyclic alkaloid, senecicannabine (41), has been isolated from Senecio cannabifolius by Furuya and co-workers, 

The mass spectrum of (41) was typical for a macrocyclic diester of retronecine (1), and the p.m.r. chemical-shift difference of 

The presence of the two epoxide groups was indicated by the C n.m.r. spectrum. Hydrolysis of senecicannabine yielded (+)-retro-necine (1), and the proposed structure (41) was confirmed by X-ray analysis. 

A retronecine ester is reported to be present in S. otites Kunze ex DC. 

Bulgarsenine (61) has also been isolated from Senecio doronicum L. together with a new alkaloid, doronenine (62).28 The structure and absolute configuration of doronenine were established by X-ray structure analysis.29 The structure (63) of the saturated y-lactone (ds-nemorensic acid) that was obtained on alkaline hydrolysis of doronenine was also determined by X-ray crystallography.30 

A new minor constituent of Senecio jacobaea L. has been shown to contain chlorine from its mass spectrum, which showed a molecular ion at m/z 38-5 and an ion at m/z 350 due to loss of chlorine.31 Senkirkine and integerrimine were previously isolated from S. antieuphorbium Sch. Bip. (c/. Vol. 3, p. 84). Senaet-nine and isosenaetnine have now been found in this species.32 Otosenine has again been isolated from S. cineraria DC.33 Bulgarian 5. erucifolius produces senecionine and seneciphylline.34 The amount of senkirkine present in specimens of Tussilago farfara obtained from several countries has been determined.35 

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Zhao, X., Chan, M., and Ogle, C. 1989. The identification of pyrrolizidine alkaloid-containing plants—a study on 20 herbs of the Compositae family. Am. J. Chin. Med. 17, 71-78. 

Alkaloids are known in a few members of the family. Tests on 45 samples which included 37 species resulted in three positives in plants known to be alkaloidal (Dioscorea dumetorum, D. hispida, D. alaia) and in two of 13 other unidentified Dioscorea species. The remainder were negative Dioscorea abyssinica, D. alata, D. batatas, D. bucha-nanii, D. bulbifera, D. composita, D. cotinifolia, D. doryophora, D. dregeana, D. esculenla, D. hemicrypta, D. hirtiflora, D. mexicana, D. pentaphylla, D. quartiniana, D. retusa, D. sylvatica, D. trifida, Tamus edulis. 

Diterpenoid alkaloids have been isolated from the genera of the families Ranunculaceae (Aconitum, Consolida, Delphinium, Thalictrum), Garryaceae (Garraya), Rosaceae (Spiraea), and Compositae (Inula). These alkaloids can be divided into two broad categories norditerpenoid alkaloids (based on a C -skeleton) and the diterpenoid alkaloids (based on a Cft-skeleton).1 The chemistry of the diterpenoid alkaloids has been reviewed in earlier literature. ... 

Pyrrolizidine alkaloids have a wide distribution, but are characteristic of certain genera of the Boraginaceae (e.g. Heliotropium, Cynoglossum, and Symphytum), the Compositae/Asteraceae (e.g. Senecio) and the Leguminosae/Fabaceae (e.g. Crotalaria). The pyrrolizidine bases rarely occur in the free form, but are generally found as esters with rare mono- or di-basic acids, the necic acids. Thus, senecionine (Figure 6.18) from Senecio species is a diester of retronecine with senecic acid. Inspection of the ten-carbon skeleton... 

Pyrrolizidine alkaloids are included in a list of alkaloids that have been isolated from the Compositae.23 All reports this year are concerned with the tribe Sene-cioneae. Definite identification of pyrrolizidine alkaloids from two new genera,... 

Pyrrolizidine alkaloids are a large family of similar chemicals found in over 6,000 different species of plants in the Leguminosae, Compositae, and Boraginacae families. For example, plants of the Senecio, Heliotropium, and Crotolaria species, many of which occur as weeds throughout the world, produce these alkaloids. About half of the pyrrolizidine alkaloids have... 

Syneilesine (12) from Syneilesis palmata (family Compositae) is an ester of otonecine with a new Cw necic acid belonging to the senecic acid biogenetic class. The diester nature of the alkaloid was revealed by i.r. maxima at 1735 and 1720 cm and by signals in the Cn.m.r. spectrum at 171.4 and 176.7 p.p.m. Alkaline hydrolysis gave three lactones designated as syneilesinolides-A (13), B... 

All the principal alkaloids of both groups possess as a common structural feature the 4-methoxyquinoline unit, in consequence of which they undergo a typical isomerization to iV-methyl-4-quinolones on vigorous treatment with methyl iodide. This reaction, which has been of considerable assistance in the elucidation of the structures of the alkaloids, also provides a chemical relationship with the alkaloid of Eehinopa species (Compositae), which was shown to be W-methyl-4-quinolone itself. The isomeric lV-methyl-2-quinolone occurs in Angostura bark. 

It is well known that a great many structurally related diterpene alkaloids have been found in the herbaceous plants of the Ranunculaceae (Aconitum and Delphinium) and Compositae (Inula), Some of them have strong toxicity or therapeutic activities. 

As part of their extensive chemotaxonomic studies on the Compositae, Bohlmann etal (39—45) have recently discovered several new types of pyrrolizidine alkaloids with a dihydropyrrolizine nucleus in Senecio species. These are all neutral compounds. The senampelines, which occur as isomeric mixtures that have not yet been separated, contain the triol (19) of unidentified stereochemistry (Table 3T). Another series of compounds contains the related oxidised dihydropyrrolizinone (20) which occurs naturally with either 7 a or 713 stereochemistry as part of the macrocyclic diester system (Table 3U). 

In their study of neutral, terpenoid metabolites from the Compositae, Bohlmann and his co-workers have discovered a series of dihydro-pyrrolizinone derivatives in Senecio species (Table 3 U). These are all macrocyclic diesters containing 12-membered rings, although it is interesting that macrocyclic diesters with both a and p stereochemistry at C-7 of the necine have been isolated. A related series of open chain esters, the senampelines (Table 3 T), have also been discovered. This work does indicate the need to carry out careful examination of both basic and neutral fractions from plant extracts when searching for pyrrolizidine derivatives. The extent of these new derivatives should also be ascertained by reinvestigating species of other families known to contain pyrrolizidine alkaloids. 

Quinolizidine alkaloids (lupine alkaloids) occur in the family Leguminosae, especially the subfamily Papilionaceae. They are also found in some species of other families such as Chenopodiaceae, Berberidaceae, Papaveraceae, Nymphaeaceae, Ranunculaceae, Scrophulariaceae, Solanaceae, Compositae, Rubiaceae, Monimiaceae, Ericaceae, and Adociidae. 

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