Funtumia alkaloids

Triterpene (Steroid) Solanum alkaloids Veratrum alkaloids Funtumia alkaloids Holarrhena alkaloids Buxus alkaloids Salamander alkaloids... 

The steroidal alkaloids have a nucleus based on 21, 24, or 27 carbon atoms (Fig. 44). The C21 alkaloids are pregnane-derived with nitrogen inserted at C-3, at C-20, or at both positions. They are characteristic of the Apocynaceae Funtumia and Holarrhena species) and the Buxaceae Buxus species). The Buxaceae also produces C24 alkaloids based on the cycloartane skeleton. The most interesting alkaloids are those in the Solanaceae and the Liliaceae. These are C27 alkaloids, and examples include solasodine and solanidine many derivatives are glycosylated. The alkaloids from the Liliaceae, such as veratramine of the white hellebore (Veratrum album), were formerly used for cardiac... 

Steroid alkaloids were also found in Funtumia and Malouetia. The genus Funtumia comprises tropical trees indigenous to equatorial and West Afrika. Alkaloids found therein belong to types I and II. Many contain only one atom of nitrogen and an oxygen function in positions 3 or 20 in comparison Holarrhena alkaloids exhibit this type of substitution much less frequently. 

The genus Malouetia occurs in both Africa and South America. It is distinguished by the same types of alkaloids as Funtumia and Holarrhena. Of particular interest is the isolation of the quaternary alkaloid malouet-ine with curarizing effect in the African Malouetia, bequaertiana Woods. It is probable that the same effect produced by the Venezuelan drug guachamacd can be attributed to some alkaloids of the South American Malouetia (3). 

These alkaloids were first isolated from insoluble oxalate fraction from Funtumia africana (Benth.) Stapf. (17,18). 

Funtumafrine-B (XXX) and funtumafrine-C (XXXI) were obtained from the leaves of Funtumia africana via the soluble oxalates. The IR-spectrum of both alkaloids disclosed the presence of a carbonyl group (1706 cm i) and their structure was established by the preparation from funtuphyllamine-B (furnishing funtumafrine-B) and funtuphyllamine-C (furnishing funtumafrine-C) on chromic acid oxidation 17, 18). 20a-Dimethylamino-5a-pregnan-3-one had been previously reported as a product of partial synthesis 20). 

Irehamine was isolated (39) from the leaves of Funtumia elastica (Preuss.) Stapf. The structure LIII of this alkaloid follows from its preparation from 20a-amino-3/3-hydroxypregn-5-ene via the X-carb-ethoxy derivative LII and reduction of the latter with lithium aluminum hydride. In accord with this structure irehamine was converted to funtuphyllamine-B XXVII on catalytic hydrogenation (39). 

This alkaloid was isolated from the leaves of Funtumia elastica its formation by Eschweiler-Clarke methylation of 20a-aminopregn-5-en-3/3-ol provided proof of its structiu e (LIV) which was further confirmed (39) by the result of the catalytic hydrogenation of irehine leading to funtuphyllamine-C (XXVIII). 

This alkaloid (LXXI) was isolated from the leaves of Funtumia elastica (63). The NMR-spectrum disclosed the presence of two primary amino groups, one olefinic proton (multiplet at 4.7 t), one secondary, and two tertiary methyl groups. On Ruschig deamination the alkaloid afforded progesterone and on methylation with formic acid-formaldehyde it yielded a tetramethyl derivative which proved to be identical with the known (64) 3j8,20a-bisdimethylaminopregn-5-ene. 

Isolation of this alkaloid from Funtumia latifolia and the structure 3 -dimethylamino-20a-aminopregn-5-ene (LXXIII) has been announced (35a). 

Monoamino-alkaloids have been isolated, in general, from the feebly basic fractions. It was in this way that Voticky and Tomko " isolated an amino-pregnane, irehine, from the leaves of B. sempervirens. Irehine was earlier extracted from the leaves of an Apocynacea, Funtumia elastica Other alkaloids isolated from different Buxus species are derivatives of methyl-pregnanes, and a few amongst them have been already described. ... 

Correlations between these alkaloids have been established, and it is shown that iV-deacetyl-epipachysamine is different from dictyophlebine, 3j5-methylamino-20a-dimethylamino-5a-pregnane, isolated from Dictyophleba lucida Epipachysamine-C is identical with dictyodiamine from the same source. The funtu-diamines-A and -B, isolated from Funtumia latifolia, are identical with epi-pachysamine-F and deacetyl-epipachysamine-A. 

The major alkaloids of the seed of Funtumia elastica are irehdiamines A, B, C, and D. Four minor alkaloids, i.e. conamine (Id), conessine (Ic), tetramethyl-horrhimine (15a), and a new base, 20-epi-irehdiamine I (15b), have now been isolated from seeds of this plant. The structure of the latter base was assigned on the basis of its n.m.r. and mass spectra, and confirmed by its synthesis from progesterone by an unexceptional route. ... 

At least 450 steroid and triterpenoid alkaloids have been reported (Verpoorte et al., 1991). Most steroidal alkaloids occur in a relatively small number of genera (Cestrum, Cy-phomandra, Lycopersicon, Nicotiana, and Solanum) of the family Solanaceae and of the family Liliaceae (Fritillaria, Veratrum, and Zygadems). Related alkaloids are known from the Apocynaceae (Funtumia, Holarrhena, and Ma-louetia) and Buxaceae. Alkaloids based on triterpenoid structures are much less common. Probably the best known ones are found in plants of the Buxaceae (especially Buxus, Pachysandra, and Sarcococca) (Gross et al., 1985 Roddick, 1980, 1986). 

Similar types of alkaloids have been isolated from the plants of the closely related species such as Funtumia and Malouetia. It is interesting to note that an alkaloid isolated from the wood of an African Malouetia was reported to possess a curarizing effect (87). 

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