Quantitation of arbutin in extracts of Arctostaphylos species by liquid chromatography - mass spectrometry

Arbutin is a hydroquinone glycoside and a natural constituent of several vegetal species. It has different pharmacological properties. In the European Pharmacopoeia (Eu.Ph.) the “Bearberry leaf” monograph requires a 7% of AR as a minimum content. A. pungens and A. Uva-ursi belong to Arctostaphylos species and are morphologically similar, but they greatly differ in AR content, lower in A. pungens. For this reason it can be fraudulently marketed instead of A. Uva-ursi. A simple LC-ESI-MS method to quantify AR in dried leaf extracts of Arctostaphylos spp. has been developed and validated. The method was applied to the quality control of 16 “Bearberry leaf” commercial samples and it was found out that A. pungens, with an AR content lower than 2% (w/w), is sometimes marketed instead of A. Uva-ursi