Both the generic name and specific epithet of Arctostaphylos uva-ursi mean ?bearberry,? in Greek and Latin respectively. Uva-ursi is a creeping, sometimes viny shrub that has a broad circumpolar distribution (all around the North Pole, in northern temperate areas of North America, Europe, and Asia). It is a polyploid complex, with different populations having different numbers of chromosome sets, and has considerable morphological variation. In North America, most of this variation has been found to be induced by environmental rather than genetic factors. There are about 50 species in the genus Arctostaphylos; most are confined to western North America. The fruit, a small red berrylike drupe, is edible. Teas made from the leaves of uva-ursi are traditionally used in both Europe and North America as a urinary antiseptic for bladder infections and as a diuretic for kidney stones.

There have been no clinical trials of products containing only uva-ursi, although clinical experience with the herb is sufficiently extensive that the German Commission E formally approved its use in phytotherapeutic products and prescriptions. Animal studies have confirmed its activity; as it increases urinary flow but not relative sodium excretion, it is technically an aquaretic rather than a diuretic. The active compound present in greatest quantity is arbutin, which is processed in the digestive tract into a related compound active against bacteria. Other compounds present include saponins and phenolic acids. Uva-ursi has been shown to act synergistically to improve the beneficial activities of dexamethasone ointment and the activities of beta-lactam antibiotics against methicillin-resistant staph . The active compound in uva-ursi responsible for the latter effect was not arbutin but corilagin, a tannin compound previously reported from a variety of other species including Amla (Phyllanthus emblica), in which it has been proposed to be primarily responsible for that plant?s anti-atherogenic activity.

Use of uva-ursi is usually limited to a few weeks at a time, as there are several theoretical safety issues associated with long-term use. Firstly, uva-ursi contains high levels of tannins, which in excessive quantities are toxic. Secondly, arbutin?s metabolite, hydroquinone, is a suspected carcinogen; although evidence so far has not shown that human users could be exposed to enough hydroquinone to pose any actual risk, Commission E recommends that uva-ursi be avoided by pregnant women and young children as a precaution. Thirdly, one Japanese study reported that a methanolic extract of uva-ursi inhibited melanin synthesis in vitro (however, in a later study of six species of Arctostaphylos, two other species strongly inhibited melanin synthesis but uva-ursi itself was much less active). If this effect actually occurred in vivo, long-term use could have detrimental effects on vision, as the eye produces melanin, and there has been one case report of an eye condition called bull?s-eye maculopathy in a woman who had used uva-ursi for three years, although no link to the herb was proven. In any case, though, the high tannin content of uva-ursi is reason enough to avoid excessive use.

Selected References

Beaux, D., J. Fleurentin, and F. Mortier. 1999. Effect of extracts of Orthosiphon stamineus Benth., Hieracium pilosella L., Sambucus nigra L., and Arctostaphylos uva-ursi (L.) Spreng. in rats. Phytother. Res. 13:222-225.

Fromard, F. 1987. Systématique du taxon Arctostaphylos uva-ursi, Ericaceae, en Europe: données nouvelles concernant les populations pyrénéenes et circumpyrénéennes. Canad. J. Bot. 65:687-695.

Matsuda, H., M. Higashino, Y. Nakai, M. Iinuma, M. Kubo, and F. A. Lang. 1996. Studies of cuticle drugs from natural sources. IV. Inhibitory effects of some Arctostaphylos plants on melanin biosynthesis. Biol. Pharm. Bull. 19:153-156.

Packer, J. G., and K. E. Denford. 1974. A contribution to the taxonomy of Arctostaphylos uva-ursi. Canad. J. Bot. 52:743-753.

Remphrey, W. R., T. A. Steeves, and B. R. Neal. 1983. The morphology and growth of Arctostaphylos uva-ursi (bearberry): an architectural analysis. Canad. J. Bot. 61:2430-2450.

Rosatti, T. J. 1982. Trichome morphology and the ecology of Arctostaphylos in Michigan. Mich. Bot. 21:171-180.

Rosatti, T. J. 1987. Field and garden studies of Arctostaphylos uva-ursi (Ericaceae) in North America. Syst. Bot. 12:61-77.

Rosatti, T. J. 1988. Pollen morphology of Arctostaphylos uva-ursi (Ericaceae) in North America. Grana 27:115-121.

Shimizu, M., S. Shiota, T. Mizushima, H. Ito, T. Hatano, T. Yoshida, and T. Tsuchiya. 2001. Marked potentiation of activity of beta-lactams against methicillin-resistant Staphylococcus aureus by corilagin. Antimicrob. Agents Chemother. 45:3198-3201.

Wang, L., and L. V. Del Priore. 2004. Bull?s-eye maculopathy secondary to herbal toxicity from uva ursi. Am. J. Ophthalmol. 137:1135-1137.