Rhamnus purshiana (D.C.)
Synonyms: Cascara sagrada, cascara bark, sacred bark, chittem bark, Californian buckthorn
Order: Rhamnaceae
Description: The bark of a shrubby deciduous tree between 5 and 8 metres high. Its reddish-brown bark is often covered with a grey lichen. The alternate dark green, elliptical to oblong-ovate leaves are finely and irregularly toothed or nearly entire. They are rounded at the base and may be obtuse or acute at the apex. Small, greenish flowers grow in finely hairy umbels, producing black, pea-sized drupes. It grows in mountainous regions of north-west North America.
Parts used: dried bark
Collection: The bark is collected in spring and early summer and should be dried and stored for at least a year before use.
Constituents: Up to 10% hydroxyanthracene glycosides consisting of cascarosides A and B , C and D, aloins A and B (chrysaloin), 0-glucosides of the anthraquinones aloe-emodin, frangula-emodin and chrysophanol and traces of the corresponding aglycones; bitter principles, lipids, volatile oil (rhamnol).
Actions: mild purgative, stimulating laxative (with a gentler action than others in its class), bitter digestive tonic, stomachic, cholagogue, antiparasitic
Indications: Atonic constipation, especially habitual constipation, dyspepsia, digestive complaints and in the treatment of haemorrhoids. It has also been used for gallstones and liver ailments.
Therapeutics and Pharmacology: The hydroxyanthracene glycosides in Rhamnus are poorly absorbed from the small intestine but they are hydrolysed by bacteria to the active aglycones, which are partly absorbed in the colon and are excreted predominantly in the faeces but also in urine, giving it an orange colour. The hydroxyanthracene aglycones inhibit water and electrolytes absorption from the colon and induce active secretion of water and electrolytes into the intestinal lumen. Due to the increased volume of contents, pressure in the intestine is increased and peristalsis stimulated. The laxative effect of Rhamnus is augmented by a pronounced bitter stimulating effect, particularly active in promoting liver function and bile secretion. Anthrones and anthranols will pass into breast milk, so this remedy should not be taken whilst breastfeeding.
Combinations: Rhamnus may be combined with Berberis, Glycyrrhiza and Zingiber in constipation.
Caution: Only bark which has been stored for a year or more should be used. Excessive dosages may result in hypokalaemia. It should be avoided in during pregnancy, lactation and in cases of intestinal obstruction. Treatment should be short-term, no longer than ten days.
Preparation and Dosage:
Regulatory Status: GSL
One dose daily at bedtime
Powdered bark: 0.25-1g
Liquid Extract BP (1973): 2-5ml
Additional Comments: The name Rhamnus is derived from the Greek rhamnos, meaning a branch.
Bibliography
Bradley, P.R. (ed.) 1992 British Herbal Compendium, Volume 1, BHMA, Bournemouth.
BHMA 1983 British Herbal Pharmacopoeia, BHMA, Bournemouth.
Grieve, M. 1931 A Modern Herbal, (ed. C.F. Leyel 1985), London.
Hoffmann, D. 1990 The New Holistic Herbal, Second Edition, Element, Shaftesbury.
Lust, J. 1990 The Herb Book, Bantam, London.
Mills, S.Y. 1993 The Essential Book of Herbal Medicine, Penguin, London (First published in 1991 as Out of the Earth, Arkana)
Mills, S.Y. 1993 The A-Z of Modern Herbalism, Diamond Books, London.
Ody, P. 1993 The Herb Society's Complete Medicinal Herbal, Dorling Kindersley, London.
Weiss, R.F. 1991 Herbal Medicine, Beaconsfield Arcanum, Beaconsfield.
Wren, R.C. 1988 Potter's New Cyclopaedia of Botanical Drugs and Preparations, C.W.Daniel, Saffron Walden.
