Uva Ursi is the dried leaf of Arctostaphylos Uva-ursi (Linne) Sprengel (Fara. Erieacece).

Uva Ursi contains not more than 5 per cent of its stems or other foreign organic matter."U.S. "Bearberry Leaves are the dried leaves of Arctostaphylos Uva-ursi, Spreng." Br.

The uva ursi, or bearberry, is a low evergreen shrub, with trailing stems, the young branches of which rise obliquely upward for a few inches. The leaves are scattered, upon short petioles, from half an inch to an inch long, obovate, or oblong-spatulate, acute at the base, obtuse at the apex, entire, with a rounded margin, thick coriaceous, smooth, shining, deep green on their upper surface, paler and covered with a network of veins beneath; furnished especially near the margin or near the midrib with minute hairs, which are usually abundant in young leaves, but may be few or absent in old leaves, especially those which have been much handled. The flowers, which stand on short reflexed peduncles, are in small clusters at the ends of the branches. The calyx is small, five-parted, reddish, and persistent. The corolla is urceolate, reddish-white, or white with a red lip, transparent at the base, contracted at the mouth, and divided at the margin into five short reflexed segments. The stamens are ten, with short filaments and bifid anthers; the ovary round, with a style longer than the stamens, and a simple stigma. The fruit is a small, round, depressed, smooth, glossy red berry, with an insipid mealy pulp and five cohering seeds.

This humble but hardy shrub inhabits the northern latitudes and high mountains of Europe, Asia, and America. On the American continent it extends from Hudson Bay as far southward as New Jersey and Pennsylvania, in some parts of which it grows in abundance. It prefers a barren soil, flourishing on gravelly hills and elevated sandy plains. The leaves are the only part used in medicine. They should be gathered in autumn, and only the green leaves selected. The present commercial supplies of this drug are partly imported from Spain and partly obtained from plants growing wild in California and the northwestern states.

In Europe the uva ursi is adulterated with the inert leaves of the Vaccinium Vitis-Idaea L. (Cowberry, Mountain Cranberry} ; these may be distinguished by being obovate, having revolute margins which are sometimes slightly toothed, and the presence of fine blackish dots or bristly points upon their lower surface. Leaves of the Chimaphila umbellata (L.) Nutt., sometimes found among the uva ursi, may be readily detected by their greater length, their cuneiform-lanceolate shape, and their serrate edges.

Description and Physical Properties.
Unground Uva Ursi. - Usually unbroken, obovate, oblong or spatulate, from 12 to 30 mm. in length, from 5 to 13 mm. in breadth; apex obtuse or rounded; margin entire, slightly revolute; base cuneate, tapering into a short, stout petiole; upper surface dark green, glabrous and shiny, finely reticulate; under surface yellowish-green and slightly pubescent, especially on the midrib; coriaceous; fracture short; odor slightly aromatic, tea-like; taste astringent and somewhat bitter.

"Powdered Uva Ursi. - Olive green; epidermal cells polygonal, those of the lower surface showing broadly elliptical stomata about 0.04 mm. in length, surrounded by 5 to 8 neighboring cells; cells of mesophyll with chloroplastids and frequently irregular masses of a carbohydrate; fragments of fibro-vascular bundles with spiral tracheae associated with narrow, strongly lignified, selerenchymatous fibers and frequently also with crystal-fibers showing mono-clinic prisms, from 0.006 to 0.030 mm. in diameter; numerous fragments made up of cells having a yellowish-brown content colored a bluish-black upon the addition of ferric chloride T.S.

Place 0.1 Gm. of powdered Uva Ursi on a watch crystal, cover with another watch crystal, and gently heat the powder: a crystalline sublimate of hydroquinonone is formed, consisting of long rods and feather-like aggregates which polarize light with a brilliant play of colors. Macerate 1 Gm. of powdered Uva Ursi with 10 cc. of boiling water, shake the mixture occasionally until cold, and filter: the filtrate yields a grayish-purple precipitate upon the addition of a few drops of ferrous sulphate T.S." U.S.

" Obovate or spatulate, about two centimetres long, yellowish-green, coriaceous, entire, shortly petiolate. Upper surface glabrous, shining, reticulate; veinlets depressed. Slight odor; taste very astringent." Br.

The commercial drug frequently consists of the entire plants and therefore contains a large quantity of stems. The latter should not be present, according to the official definition, in greater amount than five per cent. Farwell states that the leaves are sometimes very dark or blackish-green, which is probably due to carelessness in drying. (M. R., xvii, p. 35.) Holm has contributed an interesting article on the morphology of the plant. (M. R., xx, p. 95.)

Uva ursi leaves contain - besides tannic and gallic acids, quercetin, bitter extractive resin, gum, fatty matter, and salts of potassium and calcium - two glucosides, arbutin, C₁₂H₁₆O₇, and ericolin, C₃₄H₅₆O₂₁, and a crystalline principle, urson, C₂₀H₃₄0₂. There is present also a small amount of volatile oil which is probably a decomposition product of ericolin. The tannin is so abundant (6 or 7 per cent.) that the leaves are used for tanning in Russia.

Arbutin is widely diffused in the species of Ericaceae, such as species of Vaccinium, Rhododendron, and Chimaphila, also in Epigaea repens L., and Gaultheria procumbens L. Arbutin occurs in long, acicular, colorless crystals, united in tufts, and of a bitter taste. It is soluble in water, alcohol, and ether, fusible at 195� C., without action on vegetable colors, and not precipitated by ferric salts or by lead acetate or subacetate. It is a glucoside, being resolvable by emulsin, or more rapidly by boiling with sulphuric acid, into glucose and Hydroquinone, C₆H₆O₂ (arctuvine of Kawalier). Schiff has shown that arbutin is almost always accompanied by methylarbutin, C₁₂H₁₅(CH₃)0₇ + H₂O. This latter compound has been made synthetically by Schiff (B. Chem. G., 1882, p. 1841) by acting upon arbutin with methyliodide and potassium hydroxide in methyl alcohol solution, and purely synthetically by Michael (B. Chem. G., 1885, p. 118) by the action of methyl-hydroquinone and acetochlorhydrose. It is decomposed by dilute acids into glucose and methylhydroquinone. Upon heating 1 part of arbutin with 8 parts of manganese oxide, 2 parts of sulphuric acid, and 1 part of water, it gives off the penetrating odor of quinone. The aqueous solution is rendered blue by a small quantity of solution of ferric chloride and green by a larger quantity. It dissolves in sulphuric acid, forming a colorless solution, turning red after a short time; a trace of nitric acid turns this solution yellow-brown. A good test for arbutin is that of Jungmann: Phosphomolybdie acid added to an alkaline solution of arbutin gives a blue color.

A. G. Perkin has obtained from the leaves of uva ursi a yellow coloring principle of the composition C₁₅H₁₀O₇, crystallizing in glistening yellow needles. On fusion with alkali, phloro-glucinol and protocatechuic acid were formed. Though resembling quercetin in these points, it forms deep green solutions with diluted potassium hydroxide. (A. J. P., 1898, 584.) Shippee and Fogele (Chem. Neivs, 1918, exvii, 254) analyzed the fruit of uva ursi commonly known as red bearberry or kinnikinic and report protein 4 per cent., sugars (chiefly levulose) 21 per cent., a dark gummy substance and 2.9 per cent, of ash.

Uses. - Uva ursi is used to-day almost exclusively in the treatment of catarrhs of the urinary tract, especially acute cystitis. Although by some it is believed to exercise an astringent and alterative influence on these membranes, it is probable that its action is simply that of a mild antiseptic. Lewin (V. A. P. A., 1883, xcii, p. 517) attributes its virtues to the arbutin which is decomposed in the system liberating hydro-quinone. Bass, however (Z. E. P. T., 1912, x, p. 120), is doubtful whether enough hydroquinone can appear in the urine to exercise any antiseptic effect. But whether or not its virtue is due to arbutin or some other principle, the clinical evidence is strong that uva ursi is a useful drug in these conditions. Formerly it was also employed in gravel, nephritis, urethritis, and menorrhagia, but has been largely abandoned. Because of the formation of hydroquinone in the body the urine often acquires a greenish color from the use of uva ursi. Arbutin has been employed in medicine not only for its antiseptic effect but also as a diuretic in doses of from one to three grains (0.065-0.2 Gm.).

Dose, powdered uva ursi, from twenty grains to a drachm (1.3-3.9 Gm.), but the fluidextract is usually preferred.
Off. Prep. - Fluidextractum Uvae Ursi, U.S.; Infusum Uvae Ursi, Br.; Elixir Buchu Compositum (from Compound Fluidextract of Buchu), N. F.; Fluidextractum Buchu Compositum, N. F.