2.1.4 Frangula
Synonyms Buckthorn bark; Alder buckthorn; Black dogwood; Berry alder; Arrow wood; Persian berries;
Biological Source Frangula bark is the dried bark of Rhamnus frangula Linne belonging to the family Rhamnaceae.
Geographical Source The plant is a shrub which grows abundantly in Europe, the Mediterranean coast of Africa and Western Asia.
Preparation The preparation of frangula bark resembles to that of cascara bark (see section 2.1.3). Just like the cascara bark, the frangula bark must be aged for at least a period of one year before it is used therapeutically so as to permit the reduced forms of the glycosides with harsh action to be oxidised to comparatively milder forms.
Chemical Constituents The seed, bark and rootbark of Rhamnus species, specifically in Alder Buckthorn (Rhamnus alnifolia L’ Her.); in Rhamnus carthartica L., in Rhamnus purshiana DC (Cascara sagrada) consists of the two important glycosides Frangulins A and B, which were initially thought to be isomeric compounds. Later on two more glycosides known as glucofrangulns A and B have also been reported . However, the structures of Frangulins A* and B** along with Glucofrangulins A and B are given below:
Besides, frangulin the frangula bark contains emodin (see Section 4.2.1.2) and chrysophanic acid as shown below:
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* Horhammer, Wagner, Z. Naturforsch, 27B, 959, 1972.
** Wagner, Demuth, Tetrahedron Letters, 5013, 1972.
Substituents/Adulterants As the activity of Frangula Bark corresponds to that of cascara sagrada, it finds a good substitute and comparable usage in Europe and the Near East. Interestingly, the drug substances obtained from the ripe and duly dried fruits of Rhamnus catharticus Linn., are invariably employed in Europe and the Near East for their recognised cathartic therapeutic activity.
Uses It is mostly used as a cathartic.
