Comparison of Quercetin derivatives in ethanolic extracts of red raspberry (Rubus idaeus L.) leaves

Ethanol extracts from 41 raspberry leaf accessions were studied. The plants of Rubus idaeus L. were collected in different natural habitats of Lithuania located in 26 districts and replanted in the experimental field of the Institute of Botany, Lithuania. The total amount of phenolic compounds in leaves varied from 0.3 to 2.2 mg of gallic acid equivalents (GAE) in 1 g of dry leaves. Quercetin glucuronide, quercetin-3-glucoside and quercetin glucosylrhamnoside (rutin) were identified in the extracts by HPLC/UV/MS. Remarkable differences in the composition of the extracts were observed indicating that herbal tea preparations containing Rubus idaeus leaves, which are used for phytotherapeutic purposes need more detailed examination in order to standardise their possible functional properties and pharmacological effects