Hunteria eburnea

An investigation of Aspidosperma marcgravianum (23) led to the isolation of 18,19-dihydroantirhine (14). The quaternary Ab-(3-methochloride derivative of 14 (compound 15) was previously found in Hunteria eburnea Pichon (22). 

The bases so far described from Hunteria eburnea Pichon (Table I) are made up of a large number of quaternary bases (27), the structures of five of which have been elucidated (27, 28). Interestingly, none of these... 

These bases also occur in Hunteria eburnea (35, 36). 

Revised formula this base also occurs in Hunteria eburnea (40). 

The structures of haplophytine and cimicidine are still obscure in a recent investigation of the constituents of H. cimicidum, five additional bases were isolated, but no further data concerning haplophytine and cimicidine were reported (5). The additional bases include the two epimers eburnamine (II R = a-OH) and isoeburnamine (II R = jS-OH), which are characteristic alkaloids of Hunteria eburnea Pichon, and O-methyleburnamine (II R = a-OMe). The constitution of this last base was established by its conversion by boiling alcoholic picric acid into the picrate of eburnamenine (HI), and by its oxidation with chromic oxide in pyridine to the lactam eburnamonine (II R = =0). Two new bases were also isolated, namely, haplocine and haplocidine. 

An X-ray analysis of hunteracine from Hunteria eburnea shows it to be a salt (64) of a novel type. Its relationship to the other alkaloids of this group can be seen by assuming the loss of the C(16)-substituents of stemmadenine (65) and C(7)-hydroxylation, followed by nucleophilic closure of the basic nitrogen on to the indole a-position. 

These two bases, pleiomutine from Pleiocarpa mutica Benth. and umbellamine from Hunteria umbellata (K. Schum.) Hall. F. Carpodinus umbellatus K. Schum., Polyodoa umbellata Stapf., Picralima umbellata Stapf.), possess a common building block, namely 14,15-dihydroeburnamenine (229). This is bonded through C(14) to the aromatic ring of the second monomeric component, an indoline. Umbellamine is probably identical with the alkaloid hunterine, of unknown constitution, from Hunteria eburnea Pichon. ... 

As well as (+)-l,2-dehydroaspidospermidine (41a) ( = eburenine), eburine (40m) and eburcine (40n) have been obtained from Hunteria eburnea.5ld... 

Le Men and co-workers have examined the seeds of Hunteria eburnea Pichon and, as well as several known alkaloids, three new alkaloids were isolated (39) and their gross structures defined. In a subsequent publication... 

A new dimeric hypotensive alkaloid has been reported from Hunteria eburnea Pichon (29). Hunteriamine, C39H48N4O2 CH2 was amorphous and gave crystalline salts (perchlorate, mp 279°-281° decomp. [a]jj -1-29° in MeOH pif 6.50 hydrochloride, mp 310°-315° decomp. [a]p -f27° in MeOH pA 6.56 hydroiodide, mp > 300°). The alkaloid has a UV-spectrum typical of a 2,3-dialkyl-5-hydroxyindole and a bathochro-mic shift was observed in base. In the IR-spectrum OH/NH bands were... 

The tertiary alkaloid pleiocarpamine, C20H22N2O2 (mp 159°), was first isolated 2) from the roots of Pleiocarpa mutica Benth. and subsequently (3) from the bark of Hunteria eburnea Pichon (both Apocynaceae). It possesses (2) an A-substituted indole chromophore and its IR-spectrum indicated the presence of a carbonyl group (1727 cm i in Nujol or KBr) OH and NH absorptions were absent. Analysis revealed the presence of one methoxyl and one C-methyl group and the absence of A-methyl groups. 

These three alkaloids occur in two species of Pleiocarpa and Hunteria eburnea and were originally attributed the structures CLIII-CLV (32). Although NMR-evidence for the hydroxymethylene group attached to C-3 was not obtained the presence of this group was suspected from the production of formaldehyde on heating pleiocarpoline. Later evidence,... 

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