Cephaeline structure

Fig. (2). The structures of emetine (1), cephaeline (2), psychotrine (3), O-methylpsychotrine (4), emetamine (5), protoemetine (6)...

The effects of lAA, NAA and 2,4-D on the growth and alkaloid yields of root cultures in MS liquid medium are shown in Fig. (31). The cultured roots produced much more cephaeline than emetine, although the rootlets of the parental plant cultivated in a greenhouse contained almost the same amounts of emetine and cephaeline, i.e. 1.6% and 1.9% dry weight, respectively (Table 4). The roots grew well in a liquid medium in the presence of 5 mg/1 NAA, while the roots formed calli and swelled in the presence of 10 mg/1 lAA, and NAA and 0.5 mg/1 2,4-D and were not suitable for the alkaloid formation. Therefore, organized structures such as roots may be important for the biosynthesis of emetine and cephaeline. 

The structure of tubulosine (83) was derived principally from its mass spectrum which is similar to that of the Ipecacuanha alkaloid cephaeline and is characterised by main peaks at m/e 288, 274, 201, and 187," cf. (83). Oxidation of (83) gives... 

Dried roots contain from 2 to 3% alkaloids, of which emetine (60 to 75%) is the most effective. Cephaeline (methyl emetine) is next in abundance, but is not as effective as emetine. Other components are emetamine, psycotrine and methyl psycotrine. The structures of these are shown below. 

Emetine and cephaeline possess two phenylethylamine units derived from phenylalanine, and a central structure consisting of nine carbons of a monoterpene unit, which is also found in the ajmaline (Seaion 2.10), strychnine (Section 2.14), and quinine (Section 2.17) alkaloids.This partial structure is derived from geraniol through secologanin by the loss of one carbon, as was established in the case of cephaeline [1]. 

Emetine was isolated at the beginning of the nineteenth century, and its chemical structure was determined in the middle of the twentieth century [2].The absolute stereochemistry was clarified [3], and the total synthesis of this alkaloid was achieved [4,5]. On the other hand, cephaeline was isolated early in the twentieth century [6], and its chemical structure, including absolute stereochemistry, was reported at almost the same time as that of emetine [7]. 

Catechol and hydroquinol are also attacked by nitrous acid, but the reducible products of this reaction were not identified. Nevertheless, the two waves resulting from the reaction of the catechol grouping in rutin with nitrous acid can be used for analytical purposes. Similarly quecitrin can also be determined. In a similar manner and by following the procedure given for morphine, cephaeline was determined, although the structure of the reducible compound has not been proved. In the determination, a 100-foId excess of emetine does not interfere and it can be applied to tinctura ipecacuanhae and injections. 

Ipecac alkaloids [178, 195, 196] t Part of the structure of the ipecac alkaloids, e.g. emetine 6.281) and cephaeline 6.280) [heavy bonding in 6.280) is closely similar to the terpenoid fragment of the alkaloids just discussed (Section 6.6.2) the remaining atoms are accounted for by two phenethylamine units. Investigations which have paralleled those of the terpenoid indole alkaloids have established the origins of these alkaloids (see Scheme 6.50). Desacetylisoipecoside 6.277) is the key intermediate for 6.280)... 

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