Chemosystematic Value of Flavonoids from Crataegus x macrocarpa (Rosaceae) with special Emphasis on ( R )‐ and ( S )‐Eriodictyol‐7‐ O ‐glucuronide and Luteolin‐7‐ O ‐glucuronide

The chemotaxonomic investigation of Crataegus x macrocarpa , a hybrid of C. laevigata and C. rhipidophylla , presents the qualitative and quantitative composition of its flavonoid pattern in relationship to its parent species for the first time. Six flavonoids were identified as vitexin‐2″‐ O ‐rhamnoside ( 1 ), vitexin ( 2 ), isovitexin ( 3 ), rutin ( 4 ), hyperoside ( 5 ), and isoquercitrin ( 6 ). Furthermore, two flavonoids were isolated from C. x macrocarpa and identified as a diastereoisomeric mixture of ( R )‐ and ( S )‐eriodictyol‐7‐ O‐β‐ D ‐glucuronide ( 7 ) and luteolin‐7‐ O‐β‐ D ‐glucuronide ( 8 ) by means of 1D‐ and 2D‐NMR, MS, and UV experiments. Compounds 7 and 8 were isolated for the first time from Crataegus species. While missing in C. laevigata , their occurrence in C. rhipidophylla additionally emphasizes its chemotaxonomic relationship to C. x macrocarpa.