Since antiquity, Euphorbia species have been used for multiple purposes. The leaves and branchlets of Euphorbia lancifolia Schlecht were used by Mayam Indians to produce a tea named Ixbut which is reported to act as a galactogogue, increasing the flow or volume of milk in postpartem women. Some species have been used for treatment of cancer, tumors, and warts for more than 2000 years. This is the case for E.fischeriana Steud., that was used in traditional Chinese medicine as an antitumor drug. Medicinal uses of Euphorbia species include treatment of skin diseases, warts, intestinal parasites, and gonorrhea. Table Some species of Euphorbia used in folk medicine summarizes the uses in folk medicine.
Table Some species of Euphorbia used in folk medicine
|Species||Used as treatment of|
|E. antiquorum L.||Dyspepsia|
|E. caudicifolia Haines||Purgative, expectorant|
|E. fischeriana Steud.||Antitumor|
|E. genistoides Berg.||Diaphoretic|
|E. helioscopia L.||Bronchitis|
|E. hirta L.||Antihistaminic|
|E. hirta L.||Heart diseases|
|E. humifusa Willd.||Jaundice|
|E. lancifolia Schelect||Galactogogue|
|E. millii Desmoulins||Hepatitis|
|E. nerifolia L.||Antipyretic|
|E. ruspolii Chiov.||Disinfectant collyrium|
|E. splendens Bojer||Anticancer (antileukemic)|
|E. supina Rafin.||Diarrhea, purulent swellings|
|E. thymifolia L.||Galactogogue|
|E. tirucalli L.||Neuralgia|
Phytoconstituents Isolated from Euphorbia Species
Diterpenoid esters with diterpene skeletons of the tigliane (e.g., phorbol esters), daphnane (e.g., resiniferonol esters), and ingenane (e.g., ingenol esters) are responsible for most of the biological effects of the latex, including tumor promotion and cell proliferation. In contrast to the diterpenoid esters of the tigliane, ingenane, and daphnane type, the polyfunctional macrocyclic diterpenoids with skeletons of the lathyrane (e.g., lathyrol, ingol, and jolkinol) and jatrophane (e.g., jatrophone, kansuinines A and B, euphornin, euphoscopins A to D, characiol, and derivatives thereof) are inactive as irritants or as tumor promotors, as tested so far. Some derivatives of these macrocyclic diterpenes (e.g., jatrophone) exhibit antileukemic activity instead of acting as irritants.
According to Hecker (1987), the concentrations of diterpenoids in the latex are very small. Carbohydrates, lipids, amino acids, alkaloids, enzymes, and haemagglutinins have been isolated from the latex of Euphorbia species. Uemura and Hirata (1971) isolated two new alkaloids, milliamines A and B from E. millii. Nonutilizable starch and conjugated fatty acids were also isolated from laticifers of some Euphorbia species. According to Calvin (1984), about one third of the latex compounds from species of this genus are apolar, type hydrocarbons. The hydrocarbon fraction of the latex of some Euphorbia species includes polyisoprenes. However, the major compounds of the hydrocarbon fraction of the latex of almost all the Euphorbia species studied up to now are triterpenoids. Triterpenoids are also the major constituents of the hydrocarbon fraction obtained from the biomass of Euphorbia plants after extraction by hexane. Along with the latex triterpenols, this hydrocarbon fraction includes the constituents of epicuticular waxes (phytosterols, wax triterpenols, wax esters, alkanes, alkanols, fatty acids). The phytoconstituents isolated from Euphorbia species were reviewed by Singla and Pathak (1990).
Potential of Euphorbia species as Energy and Raw Chemicals Resources
After the oil embargo of the early 1970s, hundreds of species of Euphorbia and other genera were screened for their content in biocrude, with the assumption that one of the most promising options for producing liquid fuels from biomass is the direct extraction of the low molecular weight nonpolar constituents of plants. The criteria for the selection of the best candidates for energy cultures were: high concentrations of hydrocarbon-like compounds, and high production of biomass in marginal lands. Following these criteria, Euphorbia lathyris was selected for establishment and maintenance of experimental cultures in California and Spain. E. tirucalli has been studied in experimental plantations, namely in Kenya (100 ha). These field cultures, established by traditional methods of sowing and/or transplantation, have allowed the study of the ability of these crops to produce fuel and chemicals under different conditions of irrigation and plant density.
Euphorbia characias Latex in Mediterranean Rural Middle Ages Communities
Euphorbia characias is a native species of mediterranean regions, growing wild in Portugal in marginal lands, namely at the south of the Mondego River. During the Middle Ages the seeds and latex of wild plants of this species were used as powerful purgatives. The latex was taken as pills or as lenticular tablets after mixing with the flour of some oleaginous seeds. The latex was also used to destroy warts and, mixed with olive-oil, as a hair-remover. The crushed and ground plants of E. characias were also used in lakes and rivers by fishermen, enabling the capture of the fish immobilized by the rapidly dissolved poison. As with other species of Euphorbia, E. characias is highly toxic and extremely harmful to the skin, mucous membranes, heart, liver, and stomach.
Diterpenoid esters with diterpene skeletons of tigliane, ingenane, and dap-hnane, responsible for the irritant and tumor-promoting activities, have been isolated from the latex of this species. Nonirritant macrocyclic diterpenoids belonging to the lathyrane and jatrophane types were also identified. Lectins, proteins, carbohydrates, and enzymes such as ester-ases, diamine oxidase, and peroxidase were also isolated from polar fractions of the latex of E. characias.
Euphorbia characias as Source of Lipid Compounds and Biomass
Although in the Middle Ages E. characias was an important species used in folk medicine by rural communities of the mediterranean regions, the local populations do not use it nowadays as a natural resource. However, taking into account the growing importance of the Euphorbia species as alternative sources of raw chemicals and biofuel, the production of lipid compounds by wild and micropropagated plants, calli, and suspended cells of this species was studied.
The production of plant biomass can be obtained by in vivo or in vitro techniques. In vivo, by sowing or by plant propagation following the traditional methods of cuttings and transplantation, in vitro, by micropropagation and transfer of the micropropagated plantlets to the field or by establishment and permanent maintenance of cultures of calli or suspended cells.
The study of biomass growth during the developmental cycle of E. characias plants propagated by traditional methods was performed in large plots by Coppola and Brunori (1984). In our studies, wild field-growing plants were used either for determination of crude oil content and composition or as source of primary explants for initiation of cultures of micropropagated plants, calli, and suspended cells.
Summary and Conclusions
The total crude oil content of the aerial part of wild plants of E. characias varies from 5 to 8% of the dry weight, depending on the season. The major compounds identified in this fraction were the 4,4-dimethyl sterols lanosterol, lanosterol isomer, cycloartenol, and 24-methylene cycloartanol, the triterpenone lupene-3-one, the hydrocarbons nonacosane, hentriacontane, and tritriacontane, and the fatty acids 12:0, 14:0, 15:0, 16:0, 18:0, 18:1, 18:2, 18:3, 20:0, 22:0, and 24:0. The same compounds are also produced by micropropagated plants. Micropro-pagated plants gave crude oil yields higher than those obtained from wild plants. The latex of this species contains compounds with high biological activity, some of which, namely diterpenoids, may, in the future, become important for the chemical and pharmaceutic industry. Calli and suspended cells do not accumulate the 4,4-dimethyl sterols found in the latex of the parent plants but they produce and accumulate high amounts of 4-demethyl sterols beta-sitosterol, campesterol, and A5-avenasterol). The specific content of these compounds varies considerably during the growth cycle of calli and suspended cells. The maximum specific accumulation of these compounds occurs at the end of the exponential phase.
Plants of E. characias are potential sources of compounds for the petrochemical industry, with a value similar to plants of other species of this genus, namely E. lathyris. The utilization of heterotrophic cultures of calli and suspended cells for energy purposes seems to be a remote hypothesis, since the production of lipidic compounds depends on the exogenous supply of another energy-resource (e.g., sucrose) as well as on other expensive resources. However, contrarily to the triterpenols produced by in vivo plants of E. characias, the sterols produced by calli and suspended cells of this species can be used by the pharmaceutical industry as raw chemicals for the production of therapeutic steroids.