Arctostaphylos uva-ursi (Bearberry)

Bearberry leaf (the primary medicinal part) is not consumed as a food source, so macronutrient profiling is not nutritionally relevant; however, its key bioactive compounds are well-characterized. Arbutin (hydroquinone glucoside) is the primary active constituent, present at approximately 5–15% dry weight in leaves, with some reports citing up to 17% in high-quality specimens. Upon oral ingestion, arbutin is hydrolyzed in the gut and urine to free hydroquinone, which exerts antimicrobial activity specifically in alkaline urine. Methyl arbutin is also present at lower concentrations (1–3% dry weight). Tannins are abundant, comprising 15–20% dry weight, predominantly gallotannins and ellagitannins including corilagin, which contribute astringent properties and may reduce gastrointestinal absorption of other compounds (bioavailability-limiting effect). Gallic acid and ellagic acid are present as free phenolic acids at approximately 0.5–2% dry weight. Flavonoids including quercetin, isoquercitrin, hyperoside, and myricetin are present at roughly 1–2% combined dry weight. Ursolic acid (a pentacyclic triterpenoid) is found at approximately 0.4–0.7% dry weight. Allantoin is present in trace amounts. Tannin content significantly impacts bioavailability of arbutin by potentially binding to intestinal transporters; alkaline urine pH is required for optimal hydroquinone antimicrobial activity post-hydrolysis. Preparations are typically aqueous infusions or standardized extracts; cold-water infusions are sometimes preferred to reduce tannin extraction while retaining arbutin content.