The source of dried buckthorn bark, the alder buckthorn, is a shrub native to Europe and western parts of Asia (Schulz et al., 1998). Its medicinal use as a purgative laxative dates back to at least 1650, when buckthorn berries first appeared in the London Pharmacopoeia (Trease and Evans, 1989). In the United States, buckthorn was included in the National Formulary as an official drug from 1820 to 1830 and again from 1880 to 1910 (Boyle, 1991; Tyler, 1994).
Buckthorn bark is an ingredient in laxative teas, extracts, and tablets in Europe. It is also added to sunscreens (Leung and Foster, 1996). In the past, buckthorn was among the botanicals included in Harry Hoxsey's folk cancer remedy, the Hoxsey formula (Hartwell, 1971). Although current adaptations of the Hoxsey formula tend not to include buckthorn bark, tests have demonstrated that the anthraquinone derivatives in buckthorn may have anticancer effects. In particular, emodin, which is sometimes referred to as frangula emodin, frangulic acid, and rheum emodin, has stopped the growth of potato tubers, inhibited Walkers sarcoma in vitro, and is cytotoxic to at least three human tumor cell lines. These effects may be due to antiangiogenic actions. The same constituent is also found in many other plant species, including yellow dock and rhubarb (Trease and Evans, 1989; Harborne and Baxter, 1993; Kupchan and Karim, 1976).
Many Rhamnus species share anthraquinone derivative constituents and provide characteristic laxative actions. These constituents were isolated by botanists early on in the study of plant chemistry. They are chemically classified as anthraquinone derivatives and give buckthorn heartwood a bright red-yellow color, used for centuries as a dye for textiles (Trease and Evans, 1989).
In the United States, Rhamnus purshiana, more commonly known as cascara sagrada, grows throughout northern California and British Columbia. Further down the Pacific coast, R. californica grows; this was a source of cathartic remedies used by Spanish priests. R. frangula is the European species; its fragile wood tastes extremely bitter and the strong odor it imparts is evidenced by its German common name, faulbaum, meaning rotten tree (Schulz et al., 1998). Although European buckthorn has been cultivated in the United States, most commercial European buckthorn is grown in Eastern Europe and Russia and sold in Europe (Trease and Evans, 1989).
Because the anthraquinones in freshly dried buckthorn bark can cause extreme gastrointestinal irritation, including severe intestinal spasm, as well as vomiting, the bark is aged for a year to allow oxidation of the anthrones (Samuelsson, 1992), or it is heated and dried in order to induce artificial aging. Either process makes the effects of buckthorn preparations suitable for treating constipation that occurs in patients with hemorrhoids, anal fissures, or post-surgical pain (Schulz et al., 1998).
Description
Buckthorn bark consists of the dried bark of the trunks and branches of R. frangula L. (syn. Frangula alnus Miller) [Fam. Rhamnaceae], as well as its preparations in effective dosage. The bark contains anthranoids, mainly of the emodin-physcion and chrysophanol type. These preparations must conform to the currently valid pharmacopeia.
Chemistry and Pharmacology
The main constituents of the dried bark are the anthraquinone glycosides A and B and frangulins A and B, which make up 37%, other anthraquinones, glycosides, dianthrones, aglycones, flavonoids, and tannins (Bradley, 1992; ESCOP, 1997; Newall et al., 1996; Wichtl and Bisset, 1994).
1,8-dihydroxy-anthracene derivatives have a laxative effect. These compounds increase the motility of the colon by inhibiting stationary and stimulating propulsive contractions. This results in accelerated intestinal passage and, because of the shortened contraction time, a reduction in liquid absorption through the lumen. In addition, stimulation of active chloride secretion increases the water and electrolyte content of intestinal contents. Systematic studies pertaining to the kinetics of buckthorn bark preparations are not available; however, it must be supposed that the aglycones contained in the drug are already absorbed in the upper small intestine. The b-glycosides are prodrugs which are neither absorbed nor cleaved in the upper gastrointestinal tract. They are degraded in the colon by bacterial enzymes to anthrones. Anthrones are the laxative metabolites. Active metabolites of other anthronoids, such as rhein, infiltrate in small amounts into the milk ducts. A laxative effect on nursing infants has not been observed. The placental permeability for rhein is very small.
Drug preparations (i.e., herbal stimulant laxatives) have a higher general toxicity than the pure glycosides, presumably due to the content of aglycones. Experiments pertaining to the genotoxicity of buckthorn and its preparations are not available. Some positive data were obtained for aloe-emodin, emodin, physcion, and chrysophanol. No data are available for their carcinogenicity.
The fresh bark contains free anthrone and must be stored for one year or artificially aged by heat and aeration. The use of illegally processed buckthorn bark, e.g., fresh bark, will cause severe vomiting, possibly with spasms.
Uses
The Commission E approved the internal use of buckthorn bark for constipation. Other conditions for use include conditions in which soft feces are desirable (hemorrhoids and post rectal-anal operations) (Bradley, 1992; Wichtl and Bisset, 1994).
Contraindications
Intestinal obstruction, acute intestinal inflammation, e.g., Crohn's disease, colitis ulcerosa, appendicitis, abdominal pain of unknown origin. Children under 12 years of age.
Side Effects
In some cases, cramp-like discomforts of the gastrointestinal tract can occur. These incidents require a dosage reduction.
With long-term use/abuse: disturbances of electrolyte balance, especially potassium deficiency, albuminuria, and hematuria. Pigment implantation into the intestinal mucosa (Pseudomelanosis coli) is harmless and usually reverses upon discontinuation of the preparation. The potassium deficiency can lead to disorders of heart function and muscular weakness, especially with concurrent use of cardiac glycosides, diuretics, and corticosteroids.
Use During Pregnancy and Lactation
Not recommended.
Interactions with Other Drugs
With chronic use or in cases of abuse of the preparation, a potentiation of cardiac glycosides due to a loss of serum potassium is possible. Also possible is an effect on antiarrhythmic agents. Potassium deficiency can be increased by simultaneous application of thiazide diuretics, corticosteroids, or licorice root.
Dosage and Administration
Unless otherwise prescribed: Cut bark, powder, or dried extracts (corresponding to 20-30 mg hydroxyanthracene derivatives, calculated as glycofrangulin A) for teas, decoction, cold maceration, or elixir. Liquid or solid forms of medication exclusively for oral use. The individually correct dosage is the smallest dosage necessary to maintain a soft stool.
[Note: According to the Austrian Pharmacopeia, the average single dose for the decoction dosage form is 1.5 g (Meyer-Buchtela, 1999; ÖAB, 1991).]
Decoction: Boil 0.5-2.5 g (Bradley, 1992) in 150-250 ml water.
Infusion: Steep 1/2 teaspoon (1.2 g) in 150 ml hot water for 10 to 15 minutes (Braun et al., 1997; Meyer-Buchtela, 1999); Or: Steep 2 g of finely cut bark in 150-250 ml boiled water for 10 minutes. Drink one cup mornings and/or evenings at bedtime (Meyer-Buchtela, 1999; Wichtl and Bisset, 1994).
Cold macerate: Soak 2 g in 150-250 ml cold water for 12 hours at room temperature (Meyer-Buchtela, 1999; Wichtl, 1989; Wichtl and Bisset, 1994).
Note: The form of administration should be smaller than the normal daily dose.
References
Boyle, W. 1991. Official Herbs: Botanical Substances in the United States Pharmacopoeias 1820-1990. East Palestine, OH: Buckeye Naturopathic Press.
Bradley, P.R. (ed.). 1992. British Herbal Compendium, Vol. 1. Bournemouth: British Herbal Medicine Association. 99-101.
Braun, R. et al. 1997. Standardzulassungen für Fertigarzneimittel—Text and Kommentar. Stuttgart: Deutscher Apotheker Verlag.
ESCOP. 1997. 'Frangulae cortex.' Monographs on the Medicinal Uses of Plant Drugs. Exeter, U.K.: European Scientific Cooperative on Phytotherapy.
Harborne, J. and H. Baxter. 1993. Phytochemical Dictionary: A Handbook of Bioactive Compounds from Plants. Washington, D.C.: Taylor and Francis.
Hartwell, J.L. 1971. Plants used against cancer: a survey. Lloydia 34(1):103-160.
Karnick, C.R. 1994. Pharmacopoeial Standards of Herbal Plants, Vol. 1. Delhi: Sri Satguru Publications. 142-143.
Kupchan, S. and A. Karim. 1976. Tumor inhibitors. 114. Aloe emodin: antileukemic principle isolated from Rhamnus frangula L. Lloydia 39(4):223-224.
Leung, A.Y. and S. Foster.1996. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics, 2nd ed. New York: John Wiley & Sons, Inc.
Meyer-Buchtela, E. 1999. Tee-Rezepturen—Ein Handbuch für Apotheker und Ärzte. Stuttgart: Deutscher Apotheker Verlag.
Newall, C.A., L.A. Anderson, J.D. Phillipson. 1996. Herbal Medicines: A Guide for Health-Care Professionals. London: The Pharmaceutical Press.
Österreichisches Arzneibuch. (ÖAB). 1991. Wien: Verlag der Österreichischen Staatsdruckerei.
Samuelsson, G. 1992. Drugs of Natural Origin: A Textbook of Pharmacognosy. Stockholm: Sweden Pharmaceutical Press.
Schulz, V., R. Hnsel, V.E. Tyler. 1998. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. New York: Springer.
Trease, G.E. and W.C. Evans. 1989. Trease and Evans' Pharmacognosy, 13th ed. London; Philadelphia: Bailliëre Tindall.
Tyler, V.E. 1994. Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York: Pharmaceutical Products Press.
Wichtl, M. (ed.). 1989. Teedrogen, 2nd ed. Stuttgart: Wissenschaftliche Verlagsgesellschaft.
Wichtl, M. and N.G. Bisset (eds.). 1994. Herbal Drugs and Phytopharmaceuticals. Stuttgart: Medpharm Scientific Publishers. 208211.
Additional Resources
Demuth, G., H. Hinz, O. Seligmann, H. Wagner. 1978. Investigations on anthraquinon glycosides of Rhamnus species, V Emodin-8-O-beta-gentiobioside, a new O-glycoside from Rhamnus frangula. Planta Med 33(1):53-56.
This material was adapted from The Complete German Commission E Monographs—Therapeutic Guide to Herbal Medicines. M. Blumenthal, W.R. Busse, A. Goldberg, J. Gruenwald, T. Hall, C.W. Riggins, R.S. Rister (eds.) S. Klein and R.S. Rister (trans.). 1998. Austin: American Botanical Council; Boston: Integrative Medicine Communications.
1) The Overview section is new information.
2) Description, Chemistry and Pharmacology, Uses, Contraindications, Side Effects, Interactions with Other Drugs, and Dosage sections have been drawn from the original work. Additional information has been added in some or all of these sections, as noted with references.
3) The dosage for equivalent preparations (tea infusion, fluidextract, and tincture) have been provided based on the following example:
Unless otherwise prescribed: 2 g per day of [powdered, crushed, cut or whole] [plant part]
Infusion: 2 g in 150 ml of water
Fluidextract 1:1 (g/ml): 2 ml
Tincture 1:5 (g/ml): 10 ml
4) The References and Additional Resources sections are new sections. Additional Resources are not cited in the monograph but are included for research purposes.
This monograph, published by the Commission E in 1994, was modified based on new scientific research. It contains more extensive pharmacological and therapeutic information taken directly from the Commission E.
Excerpt from Herbal Medicine: Expanded Commission E Monographs Copyright 2000 American Botanical Council Published by Integrative Medicine Communications Available from the American Botanical Council.
This monograph, published by the Commission E in 1994, was modified based on new scientific research. It contains more extensive pharmacological and therapeutic information taken directly from the Commission E.