Distribution and Importance
Ammi majus L. (Bishop’s weed) is a subtropical species belonging to the family Apiaceae. It is a widely distributed species in the Mediterranean region, from the Canary Islands to Iran. Its range covers North Africa (Morocco, Egypt, Ethiopia) and all of southern Europe. The species also occurs on other continents linder similar climatic conditions: in Argentina, southern United States, and less commonly in Australia and New Zealand.
Ammi majus L. is regarded as the richest, natural source of linear furanocoumarins called psoralens. These compounds are found mostly in the fruits of this species.
The psoralens are successfully applied in photochemotherapy of numerous dermatological diseases, e.g., in treating vitiligo, psoriasis, mycosis fungoides, atopic eczema, pityriasis lichenoides, urticaria pigmentosa, alopecia areata, and others. The therapy mostly makes use of photosensitizing and antiproliferating properties of psoralens. These properties are particularly enhanced in the presence of long-wavelength UV, called UV-A (λ = 320-400 nm), hence the treatment is often referred to as PUVA therapy (psoralens + UV-A).
The use of fruits of Ammi majus in treating vitiligo has a long tradition. Medicinal virtues of this species were known to the ancient Egyptians (and were first mentioned in Ebers’ papyrus).
Most of the preparations whose photosensitizing properties are currently used in dermatological treatment methods have been developed on the basis of Ammi majus. These are, among others, such preparations as Meladinine (Memphis Chemical Co., Promedica, Basotherm, Pharma-Medica); Oxsoralen (Elder, Gerot); and Ammifurin (Medexport). The main components of these are bergapten, xanthotoxin, isopimpinellin, and imperatorin.
The biological properties of psoralens have been intensively studied in recent years. Apart from their photosensitizing and antiproliferating properties, it has been recently proved that these compounds might show calcium-antagonistic action. This discovery opens new fields for their therapeutic applications.
Ammi majus: Conclusions and Prospects
- 1. Tissues of Ammi majus L. grow satisfactorily under various conditions of in vitro cultures, so they can be used, for instance, in studies on the biosynthesis of secondary metabolites.
- 2. Secondary metabolism of Ammi majus tissues is markedly changed under conditions of in vitro culture. Both qualitative and quantitative deviations from the secondary metabolites content in comparison to that of native plants are found.
- 3. The tissues in in vitro cultures show the ability for endogenic biosynthesis of those coumarin compounds characteristic for native plants: bergapten, imperatorin, isopimpinellin, xanthotoxin, marmesin, and umbelliferone, although their contents differ from those found in native plants.
- 4. Under in vitro culture conditions, some new furanocoumarin compounds are produced (compounds C, D, and E) that are not known in the metabolism of the native plant.
- 5. Tissue culture of Ammi majus L. can offer a potential source of furanocoumarins: bergapten, isopimpinellin, and imperatorin, the maximum contents of these furanocoumarins found in the tissue culture material, equal or exceed those found in fruits from which tissue cultures were derived.
- 6. Tissue culture of Ammi majus L. may provide a source for new furanocoumarin compounds (compounds C, D, and E), hence they are also synthesized in great quantities.
- 7. The conditions in cultures (composition of growth substances, light conditions, type of culture) affect the level of biosynthesis of various metabolites. There is a possibility of stimulation of biosynthesis of particular furanocoumarins by changing the conditions of tissue culture.
Selections from the book: “Medicinal and Aromatic Plants IV”, 1993.