Scientific Name(s): Rhamnus purshiana DC
Common Name(s): Bitter bark, Buckthorn, Cascara sagrada, Cascararinde, Chittem bark, Cortex rhamni purshianae, Purshiana bark, Rhamnus, Sacred bark
The official cascara sagrada is the dried bark of the typically small- to medium-sized R. purshiana wild deciduous tree found in North America (eg, California, Oregon, Washington, Idaho, Montana) and as far north as Southeast British Columbia. The tree grows up to 18 m in height and has thin, elliptical to ovate-oblong, acutely pointed leaves. The greenish flowers are arranged in umbellate cymes, and the fruit is purplish-black, broadly obovoid, and 8 mm in length. Commercial bark is flattened or transversely curved, longitudinally ridged, and brownish to red-brown in color. The bark has gray or white lichen patches and occasional moss attachments.Leung 1980, Osol 1955, USDA 2010, WHO 2002 A synonym is Frangula purshiana (D.C.) A. Gray ex J.C. Cooper.
In traditional medicine, cascara was used as a laxative by American Indians and immigrants to America. R. purshiana itself was not described officially until 1805 and was not introduced into medicine until 1877. The berries of the European counterpart (European buckthorn, Rhamnus frangula) were described in the London Pharmacopoeia of 1650. In 2002, the FDA issued a final rule stating cascara sagrada as a nonprescription laxative ingredient is no longer generally recognized as safe and effective.Evans 1989, FDA 2002, Leung 1980, WHO 2002
The active laxative constituents of cascara include at least 6% to 9% anthracene derivatives, which exist as normal O-glycosides and C-glycosides. The 4 primary glycosides or cascarosides A, B, C, and D contain both O- and C-glycosidin linkages that are chemically designated as the C-10 isomers of the 8-O-beta-D-glucopyranosides of aloin and chrysophanol. A number of dianthrones are also present, including emodin, chrysophanol, and the heterodianthrones, as well as palmidin A, B, and C.
The free anthraquinones are likely formed in the leaves and stored in the bark, mainly as C-glycosides, with older bark containing the highest concentration. Although not a commercially viable source, R. purshiana cell suspension cultures produce anthracene derivatives.
Cascara juice also contains other nonlaxative compounds such as rhamnol (cinchol, cupreol, quebrachol); linoleic, myristic, and syringic acids; resins, fat, starch, and glucose; and malic and tannic acid. The dried seeds contain 7% to 25% protein, 13% to 57% oil, and 1% to 2% ash.
A variety of extraction methods has been examined for cascara. Boiling water prevents the loss of and changes to the compound that occur in cold water extraction. Analysis and quantification of cascara's chemical constituents have been reported, and techniques for the production of emodin derivatives have been published.Alaerts 2007, Bisset 1994, Coskun 1989, Duke 1985, Evans 1989, FDA 2002, Koyama 2008, Leung 1980, Lu 2006, Tan 2006, Wei 1992
Uses and Pharmacology
On November 5, 2002, the FDA ruled that cascara sagrada nonprescription laxative products were no longer considered safe and effective.FDA 2002 Systematic reviews published in 2001 reported the use of cascara and other laxatives in randomized controlled trials demonstrating improvement in bowel movement frequency, consistency, and symptoms, with no clear evidence regarding superiority of various treatments.Petticrew 2001 A 2010 systematic review found no clinically important results from randomized controlled trials regarding the safe or effective use of cascara in adults with chronic idiopathic constipation.Mueller-Lissner 2010 Studies conducted in elderly populations show that the majority of patients using long-term laxative preparations, including cascara, were able to discontinue laxative use when a fiber supplement was added.Khaja 2005, Mihaylov 2008, Petticrew 2001
As with other stimulant laxatives (eg, aloe, senna), anthraglycosides are responsible for the cathartic properties of cascara. Cascarosides A and B are the major principles that act on the large intestine to induce peristalsis and evacuation. More specifically, anthraglycosides produce an active secretion of water and electrolytes within the lumen of the small intestine and inhibit their absorption from the large intestine, causing an increase in bowel content volume and strengthening of intestinal dilatation pressure to stimulate peristalsis.Evans 1989, Leung 1980, WHO 2002 The emodin glycoside is also responsible for laxative action, first requiring metabolism to the active aglycone by intestinal flora and possibly increasing the excitability of the smooth muscles of the intestinal wall.Srinivas 2007, Zhang 2005 For more detailed information, refer to the Emodin monograph.
On November 5, 2002, the FDA ruled that nonprescription cascara sagrada stimulant laxative products were no longer generally recognized as safe or effective.FDA 2002 Use in children younger than 10 years is contraindicated.WHO 2002 Commercial cascara preparations include crude preparations, extracts, and essential oil.Leung 1980 Typical doses of cascara are 1 g of the bark, 2 to 6 mL as a fluid extract, or 100 to 300 mg of dried bark extract.Duke 1985 The laxative effect is generally not observed for 6 to 8 hours after administration. Because of the risk of electrolyte imbalance, use should be limited to less than 2 weeks.WHO 2002
Pregnancy / Lactation
Case reports are lacking. Long-term cascara use may lead to potassium deficiency, which can potentiate the effects of cardiac glycosides, antiarrhythmics, and corticosteroids.Abebe 2003, Vogel 2005 Interference with the absorption of other drugs is possible with anthranoid-containing plants, including senna and cascara.Fugh-Berman 2000, WHO 2002
Extended or habitual use of cascara should be avoided because it can cause chronic diarrhea and weakness due to excessive potassium loss. Long-term use can also cause melanosis coli (melanin pigmentation of the colon mucous membranes), a benign and reversible injury of the colonic epithelial cells caused by anthraquinones. In one case report, a patient developing melanosis coli was asymptomatic; however, symptoms of diarrhea, fatigue, and weight loss have been reported in other cases.Bechara 2016, Bisset 1994, Duke 1985, Grilo 2014, Kew 2013
A case report exists of intrahepatic cholestasis and consequent portal hypertension related to cascara use. It is unclear if the event was due to the cascara preparation or to adulterants.Nadir 2000 Freshly prepared cascara product contains anthrones, which can result in severe vomiting and intestinal cramping when consumed; therefore, the bark should be stored for at least 1 year before use or processed by heating or aeration to eliminate the anthrone principles.de Witte 1990
Overdose of anthraquinone laxatives results in intestinal pain and severe diarrhea, with consequent electrolyte imbalance and dehydration. Treatment is symptomatic, with special attention given to potassium and other electrolyte levels, especially in elderly patients and children.WHO 2002
No causal relationship between long-term use of cascara and colorectal cancer has been established.WHO 2002 In a rat colon carcinogenesis model, cascara did not increase the incidence of aberrant crypt foci or tumors.Borrelli 2001 In one study, samples of herbal preparations were evaluated for heavy metal contamination (cadmium, mercury, and lead), with low levels reported for cascara.Caldas 2004
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