- Clinical data 90%
- Efficacy 80%
- Security 70%
- Toxicity 30%
Folium Uvae Ursi
Arbutus uva-ursi L., Arctostaphylos media Greene, Arctostaphylos officinalis Wimm., Arctostaphylos procumbens Patzke, Mairania uva-ursi Desv., Uva-ursi buxifolia S.F. Gray, Uva-ursi procumbens Moench.
Leaf entire or nearly entire; lamina obovate, oblong or spatulate, 7–30mm long and 5–13mm wide, apex obtuse or rounded, margin entire or slightly revolute, base cuneate, tapering to a short (about 5mm long), slightly pubescent petiole. Upper surface green to brownish-green, waxy, shiny and coriaceous, finely wrinkled due to depression of midrib and veins. Lower surface greyishgreen, reticulate. Young leaves ciliate on the margins, old leaves glabrous.
Major chemical constituents
The major constituent is arbutin (5–15%). Related hydroquinone derivatives present include hydroquinone and methylarbutin (up to 4%). Gallic acid is the major phenolic carboxylic acid present, together with galloyl arbutin and up to 20% of gallotannins, flavonoids and triterpenes, mainly ursolic acid and uvaol.
Medicinal uses of Arctostaphylos uva-ursi
Uses supported by clinical data
Uses described in pharmacopoeias and in traditional systems of medicine
Arctostaphylos uva-ursi: Internally, as a mild urinary antiseptic for moderate inflammatory conditions of the urinary tract and bladder, such as cystitis, urethritis and dysuria.
Uses described in folk medicine, not supported by experimental or clinical data
As a diuretic, to stimulate uterine contractions, and to treat diabetes, poor eyesight, renal or urinary calculi, rheumatism and venereal disease. Topical applications have been used for skin depigmentation.
A 30% ethanol extract of Folium Uvae Ursi inhibited the growth in vitro of Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Serratia marcescens and Staphylococcus aureus. However, 95% ethanol or chloroform extracts had no antibacterial activity. An aqueous extract of the leaves inhibited the growth of Streptococcus mutans OMZ176 in vitro. Ethanol and ethyl acetate extracts of the leaves were active in vitro against Escherichia coli, Proteus vulgaris, Streptococcus faecalis and Enterobacter aerogenes. Arbutin is responsible for most of the antibacterial activity. Arbutin and hydroquinone inhibited the growth in vitro of Ureaplasma urealyticum and Mycoplasma hominis. After ingestion of the leaves, arbutin is absorbed from the gastrointestinal tract, and is hydrolysed by intestinal flora to form the aglycone, hydroquinone. Hydroquinone is metabolized to glucuronate and sulfate esters that are excreted in the urine. These active hydroquinone derivatives exert an antiseptic and astringent effect on the urinary mucous membranes when the urine is alkaline (pH 8.0). Their antibacterial action reaches a maximum approximately 3–4 hours after ingestion. An aqueous extract of the leaves had antiviral activity in vitro against herpes simplex virus type 2, influenza virus A2 (Mannheim 57) and vaccinia virus at a concentration of 10%. Anti-inflammatory activity Intragastric administration of a 50% methanol extract of the leaves (100mg/kg body weight) to mice inhibited picryl chloride induced ear inflammation. The extract also potentiated the efficacy of prednisolone and dexamethasone in mice. Arbutin, however, had no effect on the activity of the two steroids. Effect on glucose levels Administration of the leaves (6.35% of diet) to streptozocin-treated mice for 18 days did not reduce plasma glucose levels. Effect on calcium excretion Addition of an infusion of the leaves to the drinking-water (3g/l) of rats fed a standard diet fortified with calcium (8g/kg body weight) had no effect on urinary calcium excretion and diuresis. Antitussive activity Arbutin (50–100mg/kg body weigh, administered intraperitoneally or intragastrically) was as active as codeine (10mg/kg body weight, administered intraperitoneally) as an antitussive in unanaesthetized cats with coughs induced by nylon fibres.
Effect on skin depigmentation
Extracts of the leaves have been widely used in cosmetic preparations to lighten the skin, with the active principles being hydroquinone and its derivatives.
Toxicity and overdose
The oral LD50 of hydroquinone ranged from 300 to 1300mg/kg body weight in rodents and dogs, but was only 4286mg/kg body weight in cats. Acute exposure of rats to high doses of hydroquinone (over 1300mg/kg body weight) caused severe effects on the central nervous system, including hyperexcitability, tremor, convulsions, coma and death.
In a study without controls, urine samples from healthy volunteers were collected 3 hours after oral administration of 0.1 or 1.0 g arbutin. The urine sample (adjusted to pH 8.0) and 20 antibacterial compounds (at their usual urine concentration) were tested in vitro using 74 strains of bacteria, including Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus. Only arbutin (present in urine samples collected after administration of 1.0 g arbutin), gentamicin and nalidixic acid were active against all the strains tested. Oral administration of 800mg arbutin or an infusion of the leaves containing an equivalent amount of arbutin to healthy volunteers had strong antibacterial activity, as measured in urine samples after adjustment of the urine pH to 8.0.
During pregnancy or lactation, or in children under the age of 12 years.
Folium Uvae Ursi is also contraindicated in patients with kidney disorders.
Folium Uvae Ursi should not be used for prolonged periods. Patients with persistent symptoms of a urinary tract infection should consult a physician. Use of Folium Uvae Ursi may cause a greenish-brown coloration of the urine that darkens on exposure to air due to the oxidation of hydroquinone.
Folium Uvae Ursi should not be administered with foods or medicines that acidify the urine.
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