UVA URSI
Botanical name: Arctostaphylos uva ursi
Synonyms: Bearberry, Kinnikinnik
MAJOR CHEMICAL CONSTITUENTS
The primary medicinally active constituent is arbutin, a phenolic glycoside that generates hydroquinone as a result of glycolysis. Tannins, and flavonoids are also present. A small amount of free hydroquinone is found in the leaves. P-coumaric acid and caffeic acid, compounds with known antibacterial properties, and salicylic acid, a known bacteriostatic and anti-inflammatory agent, may be of significance. Uva ursi contains the flavonoid quercetin and the triterpenes ursolic acid, among many other constituents.
PRINCIPAL USES
TRADITIONAL AND HISTORICAL USES
Uva ursi was used by numerous native tribes of the northern United States and Canada as a diuretic or for treatment of inflammation of the genitourinary tract. It appears to have been introduced into European medical practice in the thirteenth century as a treatment for conditions of the bladder and kidney, and as such has remained in use since. Goethe is reported to have been prescribed and successfully treated for kidney stones with this herb. Early US medical botanists reported on its usefulness in the treatment of genitourinary disorders and by the late nineteenth century it was widely used by Eclectic physicians as an astringent tonic for chronic diarrhea, dysentery, and menorrhagia, as well as for genitourinary disorders and diabetes. It has had an official entry in pharmacopoeias of numerous western nations since the eighteenth century, including the British Herbal Pharmacopoeia, the National Formulary and the United States Dispensatory. It can still be found in the pharmacopoeias of numerous countries including Austria, Czechoslovakia, Egypt, France, Germany, Hungary, Japan, Russia, Switzerland, and others.
IN VITRO, ANIMAL, AND CLINICAL DATA
Uva ursi remains one of the most important and commonly used urinary tract disinfectants in modern herbal medicine, widely used in the treatment of uncomplicated acute and recurrent urinary tract infections. Midwives include the herb as an astringent anti-inflammatory in sitz baths and perineal rinses for postnatal perineal healing and as part of treatment of vaginitis and urethritis. There are few clinical trials or pharmacodynamic studies of uva ursi. In vitro studies using crude leaf preparations and extracts of uva ursi leaf have demonstrated mild antimicrobial activity against known UTI causing
organisms, including but not limited to C. albicans, E. coli, S. aureus, and Proteus vulgaris, and others. Several studies have also demonstrated antiinflammatory activity of the herb, particularly enhanced when extracts are used in combination with anti-inflammatory pharmaceutical drugs, for example, prednisolone, indomethacin, or dexamethazone.
MECHANISMS OF ACTION
The mechanisms of action of uva ursi are not fully elucidated. It appears, however, that arbutin, and its aglycone, hydroquinone—a urinary disinfectant—are primarily responsible for the herb’s antimicrobial activity. Hydroquinones are primarily hydrolyzed in the kidney because tannins prevent enzymatic activity that would normally lead to its conversion in the gut; it also appears that arbutin might be hydrolyzed in the urinary tract as a result of β-glucosidase activity stimulated by pathogenic infection. Arbutin is rapidly absorbed after consumption of tea and extract preparations, with urinary excretion of metabolites within a few hours and up to 24 hours. Antibacterial actions may be most prominent in an alkaline (pH 8) urinary environment; however, activity is not necessarily dependent on elevated urinary pH.
