The genus Cephaelis (family Rubiaceae) is comprised of about 100 species and is native to the tropics of the Americas, Africa, and Asia. Its species are mostly evergreen shrubs or small trees with opposite, undivided leaves and small flowers in terminal heads with an involucre of bracts. The plant generally starts flowering in the second year from germination, and the flowers have a five-toothed calyx, a five-lobed corolla, five stamens, and a two-branched style (). The fruits are small, usually two-seeded, berry-like drupes and their production becomes maximum three to four years after germination.
There are two pharmaceutically important species, Cephaelis ipecacuanha A. Richard (also known as Psychotria ipecacuanha Stokes and Uragoga ipecacuanha Baill), and C. acuminata Karsten. The drug ipecac (ipecacuanha root) is the dried root or rhizome of these plants, which was used in Amazonian folk medicine and was introduced into Europe in 1672 to treat amoebic dysentery ().
Distribution and Importance of the Ipecac
Cephaelis ipecacuanha, known in commerce as Rio or Brazilian ipecac, is found over a large area in Brazil, particularly in the moist and shady forests of Matto Grosso and Minas Geraes. Plantations have been established in the Matto Grosso area. It is cultivated to some extent in Malaysia, Burma, and the Darjeeling Hills of West Bengal. C. acuminata, known in commerce as Cartagena, Nicaragua, or Panama ipecac, is exported from Colombia, Nicaragua, and Costa Rica. The main differences between the Rio and Cartagena drugs are listed in Table The main differences between the Rio (C. ipecacuanha) and Cartagena (C. acuminata) drugs:
|Rio ipecacuanha||Cartagena ipecacuanha|
|Usual diameter||1-4 mm||4-6.5 mm|
|Color||Brick-red to brown||Grayish-brown|
|Annulations||Very crowded||Less crowded and less projecting|
|Starch||Individual grains up to 15 µm||Individual grains up to 20 µrn|
|Alkaloid ratio||Emetine > cephaeline||Emetine < cephaeline|
Ipecac is commonly used as an expectorant in the treatment of bronchitis, croup, asthma and whooping cough, as an emetic in cases of poisoning, and an amoebacide in amoebic dysentery. It is rich in the isoquinoline alkaloids emetine, cephaeline, psychotrine, O-methylpsychotrine, and emetamine (), emetine and cephaeline being the principal active ingredients. Because emetine has a more expectorant and less emetic action than cephaeline (), and emetine hydrochloride is used in the treatment of amoebic dysentery by injection, it is the alkaloid usually required in medicine.
Cultivation of Ipecac
Various varieties of ipecac contain different proportions of the principal alkaloids. The Rio variant (Cephaelis ipecacuanha) contains 2-2.4% alkaloids (dry wt.) of which 60-75% is emetine. The varieties derived from C. acuminata yield 2-3.5% alkaloids (dry wt.), of which emetine may constitute 30-50% (). Thus C. ipecacuanha is regarded as the best source of ipecac.
The supply of ipecac has fluctuated for many years because it is collected mainly from wild plants. In Matto Grosso, the collector partially digs the plant up from the ground and, having removed most of the roots, replaces it in the ground to produce further plants. The roots are dried in the sun or by fire and transported downriver to ports such as Rio de Janeiro, Bahia, and Pernambuco, to be exported in bales. The Rio variant is now becoming difficult to obtain commercially, and the high price favors cultivation, but only modest success has resulted from the efforts to grow the drug in Malaya and India.
Cephaelis ipecacuanha can grow from seeds as well as from leaf and stem cuttings. The plants prefer artificial shade and soil rich in humus and acidic in nature. Chatterjee et al. () studied the field cultivation of this plant to provide information for the economically feasible propagation of ipecac in West Bengal, and faced the following problems:
- Seeds lost viability after storage, although treatment with limewater or hydrogen peroxide could improve germination.
- The yield of roots was maximum after 4 years and the alkaloid content was maximum during the third and fourth year. Taking all aspects into consideration such as cost of cultivation, yield, and alkaloid contents, maximum benefit is obtained by harvesting the roots between the third and fourth years.
- Covering the plants increased the yields of roots about threefold, but this might become a major share of the total expenditure when developing the plantation. Also, selection of a cover for ipecac plants to grow is one of the very important considerations.
The ipecac plants are commercially cultivated in the lower hills of Darjeeling in India, and they are usually propagated by stem or root cuttings. Micropropagation in vitro (), which enables over 1000 plants to be propagated from a single axenic culture within six months (), is much faster and more feasible than the conventional methods. However, micropropagation in vitro should not be accounted economically feasible when considering it from a commercial standpoint, because it requires special facilities, reagents, and many instruments. It depends on the relation between the cost and profit as to whether commercial cultivation of ipecac combined with micropropagation in vitro is possible or not. Organ, root, and shoot cultures of C. ipecacuanha are very attractive for the production and study of the biosynthesis of emetic alkaloids. The roots, which were cultured for 7 weeks in 100-ml flasks under optimized conditions, yielded the comparable amount of alkaloids to the roots of 1-year-old regenerated plant (), although the ratio of emetine to cephaeline was much lower than the roots of parental plant (). In solanaceous species, it is commonly accepted that the root is the organ of alkaloid biosynthesis. In C. ipecacuanha, however, shoot cultures (without roots) as well as root cultures produced alkaloids (). This implies that biosynthesis of emetic alkaloids occurs over a whole plant. It is noteworthy that both root and shoot cultures in vitro accumulated much more cephaeline than emetine, while the roots of the parental plant contained these two alkaloids at almost the same level. The ratio of emetine to cephaeline in regenerated plants seems to change as the plants become mature.
Selections from the book: “Medicinal and Aromatic Plants IV”, 1993.