Variability of the arbutin content in wild growing populations of Arctostaphylos uva-ursi (L.) Spreng from Korab Mountain, Western Balkan

Due to the presence of arbutin and hydroquinone in the bearberry plant (Arctostaphylos uva-ursi (L.) Spreng., Ericaceae), it is widely used as a urinary tract antiseptic and diuretic. The herbal substance consists of whole or cut dried leaves, and it should not contain less than 7.00% of anhydrous arbutin (Ph.Eur.10). The supply of this herbal substance in Balkan countries mainly comes from a wild plant harvested in the mountains. It is a common practice to collect the leaves during the flowering season of the plant (June-July). There is an abundance of wild growing natural populations of bearberry on Korab Mountain that represents a unique natural resource of this herbal substance for both countries, Albania and North Macedonia. The aim of the present study was to determine the arbutin content and to assess its variability in the bearberry leaves of seven wild populations from Korab Mountain. The leaves were collected monthly (May-October) during a period of 3 years (2014-2016). The HPLC assay (Ph.Eur.10) revealed that all populations have arbutin content over 7.00% (7.03-9.42%) and that the highest content of arbutin can be attained in September/October, during the phase after the fructification. Statistical analysis showed that there is significant difference between the content of arbutin in the different populations. The content was related to the altitude of the collection site and the collection month and year.