Heimia alkaloids

Little of the chemistry of the Lythraceae was known prior to the 1960s beyond reports of the qualitative presence of alkaloids in a few genera. With the recognition of the novel alkaloid structures in Decodnn and Heimia, an examination of material from other genera gleaned from herbarium specimens was undertaken. The published results are included in those reported here. 

This report was followed by isolation of other lactonic alkaloids from Heimia salicifolia Link and Otto by Schwarting et al. (1, J) and from Heimia myrtifolia Cham and Schl. and H. salicifolia by Douglas et al. (4). 

Extracts from young seedlings of Heimia salicifolia plants were the source of three minor alkaloids. Rother and Schwarting have isolated two isomeric 1-(12-hydroxy-13-methoxy)phenylquinolizid-3-ols (63a) and (64a) and detected 1-(12-hydroxy- 13-methoxy)phenylquinolizid-3-one (65a or 65b or both) (47, 48). These alkaloids were absent in extracts of plants obtained at later stages of growth (49). These three compounds are intermediates in the current biogenetic hypothesis. 

Three minor ester alkaloids, abresoline (66), demethoxyabresoline (68), and 5-epidemethoxyabresoline (70), have been isolated from Heimia salicifolia by Schwarting et al. (51). 

Occurrence of simple quinolizidone alkaloids, ester alkaloids, and lactonic alkaloids in the same Heimia salicifolia plant species provides further evidence in support of current biogenetic hypothesis. 

The preliminary biological studies on isolated Heimia alkaloids did not confirm any central nervous system activity in rats (4). Later biological... 

Lythraceae Alkaloids.— The rate at which quinolizidine alkaloids of the cryogenine (35) type are synthesized and degraded in Heimia salicifolia has been studied as has their sequence of appearance in growing plants. " The results do not yet add to the preliminary data so far obtained on these alkaloids. ... 

Alkaloids of the family Lythraceae were reviewed in Volumes 18 and 35 of this series (595, S). The latter review, published in 1989, was devoted to developments during the period 1979-1987, and overtyped to some extent with the review on simple indolizidine and quinolizidine alkaloids in Volume 28 (1). Also worth noting is a phytochemical and phytopharmacological review on the New World flowering shrub Heimia salicifolia, an important source of these alkaloids (596). 

Lythraceae Alkaloids.—Cryogenine (18) has been shown to incorporate [3- " C]-phenylalanine in Heimia salicifolia. Oxidative degradation established the incorporation of labels at the positions shown in (18) the difference in incorporation of the two units may be a function of the stage at which they normally enter the biosynthetic pathway. Although ring d and the whole of its C3 side chain are probably derived from phenylalanine, it is not yet clear whether this precursor supplies three or only one carbon atom of the quinolizidine system. 

Anti-inflammatory Compounds.—Claims for anti-inflammatory activity of alkaloids appear in the literature from time to time, but in view of the difficulties connected with the testing of such compounds, positive results should be viewed with caution. Recently it has been stated that cryogenine from Heimia salicifolia (Lythraceae) has anti-inflammatory activity. Lythraceae have been investigated broadly during recent years, probably because of an early claim that these alkaloids have hallucinogenic properties. The structure (31) has been proposed for cryogenine. ... 

This alkaloid was isolated from Heimia salicifolia Link et Otto and its structure (66) was elucidated by spectral methods and by its reduction to decodine in which the cyclic double bond of 66 is reduced 80). 

Kaplan, H.R. and M.H. Malone 1966. A pharmacologic study of nesodine, cryo-genine and other alkaloids of Heimia sa-licijblia Lloydia 29 348-359. 

Robichaud, R.C. etal. 1964. Pharmacodynamics of cryogenine, an alkaloid isolated from Heimia salicifoUa Link and Otto. Vaxti Archives Internationales de Pharmacodynamic et de Therapie 150 220-232. 

Lema, W.J. etal. 1985. Prostaglandin synthetase inhibition by alkaloids of Heimia salicifolia "Journal ofEthnopharmacology 15(2) 161-167. 

After the recent considerable activity in the synthesis of macrocyclic Lythraceae alkaloids, published work this year has been confined to the isolation of the new aryl-quinolizidine alkaloids desmethoxyabresoline (28) and 10-ep/-desmethoxyabresoline (29) from Heimia salicifolia The structure of alkaloid (28) was established by spectroscopy and by conversion into two known compounds, the alcohol (27) (c/. Vol. 6, p. 97) obtained by basic hydrolysis and... 

A contemporary investigation of H. salicifolia and of H. myrtifolia Cham, et Schl. indicated that the alkaloid contents are such that these plants are not distinct specifically, a conclusion consonant with the view that Heimia is monotypic. The alkaloid content also indicates that the genus Heimia may be referred to Decodon. Both plants yielded lythrine, vertine, and lythridine, C23H2504N(0Me)2 (mp 219° [a]if —153°) hydrochloride (mp > 320°) 122). 

Only two new simple quinohzidines appear to have been reported in the period under review. From the leaves of Heimia salicifolia (H.B K.) Link Otto was isolated (2S,4S,9aR)-4-(3-hydroxy-4-methoxyphenyl)quinolizi-din-2-yl acetate (1345) ([ot] 4-10.7, c 0.15, MeOH). The new alkaloid is the acetate of a kno-wn Heimia alkaloid, the alcohol 1346. In addition to full spectroscopic characterization, both the gross structure and the absolute... 

In the case of QAs it has been demonstrated that the decarboxylation of lysine to cadaverine is the first step of their biosynthesis (see review in Wink, 1985). In contrast with the pyrrolidine alkaloids, which are mainly synthesized in the roots, the biosynthesis of QAs occurs in the aerial parts. The enzyme of QA formation (LE)C) was demonstrated in leaves of Lupinus polyphyllus (Wink and Hartmann, 1981) and subsequently localized in the stroma of chloroplasts (Wink and Hartmann, 1982). In QA alkaloid-bearing cultures of Heimia sali-cifolia, LEXT activity was found to be positively correlated with chlorophyll levels (Pelosi et al, 1986). It appears that QAs act not only in nitrogen storage, nitrogen transport, and chemical defense (Wink, 1985), but also in the regulation of polypeptide biosynthesis (Twardowski et al, 1982). 

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