Cortex Cascarae

Cascarae cortex (Rhamnus purshianus-trade samples)... 

E Cascarae cortex (5-7) samples are characterized by anthrone glycosides two pairs of yellow fluorescent cascarosides A/B (Rf 0.05-0.15) and cascarosides C/D (R, 0.2-0.25). The cascarosides A/B dominate. The amount of yellow fluorescent aloin (T2), deoxyaloin (R, 0.65) and the red-brown fluorescent aglycones emodin, aloe-emodin, chrysophanol (solvent front) varies. Four blue fluorescent naphthalide derivatives are detectable in the R, range 0.3-0.45. 

Fig. 76.—Photomicrograph of transverse section of Cascara Sagrada bark k, cork g, cork cambium c, cortex st, group of stone cells bf, group of bast fibers mr, medullary ray.

CASCARA, Rhamni purshiani cortex Cascara bark is more widely used than Frangula as a laxative in the USA since the trees of Rhamnus purshianus DC, family Rhamnaceae, are cultivated in Northwestern USA and Canada. Cascara has also been known as Cascara Sagrada from the Spanish name for sacred bark. Like the closely related Frangula bark, fresh Cascara bark contains reduced emodin-based glycosides. In order to convert these to milder oxidised forms the bark must either be stored for 1 year or heat treated. 

The primary active ingredients of cascara sagrada include cascarosides A, B, C, and D, but barbaloin, chrysaloin, chryophanol, emodin, and aloe-emodin are also present (Tyler, 1994 Anonymous, 1996). The anthrone glucofrangulin is present in the cortex of the European species Rhamni frangula (De Witte, 1993). As with senna and aloe constituents, these anthrones produce an active secretion of water and electrolytes within the lumen of the small intestine. In addition, the anthrones inhibit absorption of water and electrolytes from the large intestine. This causes an increase in the volume of bowel contents, and strengthens the dilatation pressure in the intestine to stimulate peristalsis (Anonymous, 1996). 

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