Decodon

Two hundred and thirty samples tested included several known from earlier literature to be positive Decodon verticillatus (17/17), Heimia myrlifolta (18/18), H. saltctfolia (10/13), Legerstroemla indica (1/3), L. speciosa (1/3), Lawsonia lanceolatum (2/3). 

Lythraceae Alkaloids.—Results showing that lysine (15) is a precursor for decodine (22) and decinine (23) in Decodon verticillatus, which were published in preliminary form (cf. Vol. 1, p. 6), are now available in a full paper.8 Label from either C-2 or C-6 of the amino-acid was found to be spread equally over C-5 and C-9 of the alkaloids, indicating that ring A derived from this amino-acid and that incorporation was via a symmetrical intermediate. Cadaverine (16),... 

The first isolation of the Lythraceae alkaloids from Decodon verticillatus (L) Ell was reported by Ferris in 1962 (2). Those were lactonic biphenyl alkaloids (type A) decinine, decodine, verticillatine, decamine, vertine, lactonic ether alcaloids, decaline, and vertaline. 

L-alaninol (24). Decinine (2) was isolated by Ferris from Decodon verti-cillatus (2, 17), from Lagerstroemia indica L. (25), and from Lythrum lan-ceolatum (9). This alkaloid was shown to be identical to the dihydro derivative of lythrine (22). 

Verticillatine (20) was isolated by Ferris from Decodon verticillatus (2). Dihydroverticillatine (21) and lagerstroemine (23) were isolated by Ferris et al. from Lagerstroemia indica (25) and sinicuichine (22) by Blomster et al. from H. salicifolia (1). Lagerstroemine was also detected in Plantago psylium... 

Six alkaloids belong to this group decaline (49), demethyldecaline (50), vertaline (51), demethylvertaline (52), lagerine (53), and methyllagerine (54). In the first two alkaloids the quinolizidine ring is trans-fused and in the latter four it is cis-fused. These compounds are listed in Table III (7, 2, 77, 25, 36, 41, 42). Decaline and vertaline were isolated by Ferris from Decodon verticillatus (2). 

Most of the work on the biosynthesis of Lythraceae alkaloids has been done by Spenser et al. (10, 84-87). First, the validity of the pelletierine hypothesis (c) of Ferris et al. (62) has been tested. The pelletierine (126) nucleus is generated from L-lysine (181) via cadaverine (182), and presumably A -piperideine (132) and its side chain originate from the acetate. Incorporation of radioactivity from 14C-labeled samples of these precursors to decodine (6) and decinine (2) in Decodon verticilatus has been investigated (85, 87). 

In the ultimate test of hypothesis c, Decodon plants were treated with (jR5 )-[6,2-14C2]- and (RS)-[6-3H,2 -14C]pclletierme to yield inactive alkaloids, whereas in concurrent experiments labeled decodine and decinine were obtained from other substrates. The accumulated evidence favored hypothesis e (see Scheme 4). 

When [2-14C]phenylalanine was administered to Decodon plants about two-thirds of the activity of decodine and decinine was located at C-2. This carbon was isolated as the a-naphthylamide of acetic acid by the Kuhn-Roth oxidation of the -propyl derivative. 

Over 40 alkaloids have been isolated from Lythraceous plants since Ferris isolated 7 alkaloids from Decodon verticillatus in 1962 (/). Before the last review in this treatise (2), the structures and stereochemistries of all Lythraceous alkaloids had been established. No reports on the isolation of new alkaloids from this family have been published since 1981. On the other hand, development of new synthetic technologies has opened new avenues to the total synthesis of Lythraceous alkaloids. The earlier classification (types A-E) of Lythraceous alkaloids introduced by Fuji et al. (J) and adopted in the last review (2) is not used in this chapter because it does not indicate the structural features. This chapter covers the literature from 1979 to 1987, except for two papers (4, 5) already included in the last review (2) in Volume 18 of this treatise. 

The possible origins of rings a, b, and c are illustrated for the alkaloids decodine (19) and decinine (20) (Scheme 4). Both [2- C]-DL-lysine and [6- C]-DL-lysine were incorporated into these alkaloids in Decodon verticillatus Degradation indicated that lysine was utilized as an intact C5N unit and, further, a symmetrical intermediate was involved. [l- C]Lysine gave totally inactive alkaloid. 

The 2D gel image analysis is performed with the Delta2D Software (Decodon GmbH, Greifswald, Germany). Three different data sets of each experiment have to be analyzed in order to screen for differences in the amount or synthesis of the proteins identified on 2D gels. 

Partial degradation of the lythraceae alkaloids decodine (22) and decimine (23), isolated from Decodon verticillatus after being fed either 2-14c or 6 4c-lysine, indicated that the amino acid enters the alkaloid in a non-random fashion through a symmetrical intermediate. It was also demonstrated that two fragments derived from phenylalanine are incorporated into decodine. 

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). 

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