Application of different analytical methods for the determination of phenolics and antioxidant activity in hawthorn (Crataegus spp.) bud and sprout herbal extracts

Hawthorn (Crataegus spp., family: Rosaceae) extracts have been used as pharmaceutical preparations owing to positive effects on cardiovascular system. The AlCl3-based official method employed for the determination of pharmacologically active compounds was compared with other techniques such as Folin-Ciocalteau method and HPLC-DAD. Antioxidant activity was determined by ABTS radical cation assay. Methods were applied on extracts from buds and sprouts collected from common hawthorn (C. monogyna Jacq., C. laevigata (Poir.) DC.) located in Northeastern Italy. Phenolic content determined by AlCl3-based method, Folin-Ciocalteau method, and HPLC-DAD was in the range 23,534-27,728, 75,284-100,616 and 57,317-58,639 mg kg-1 of dry matter (DM), respectively, in buds, and 17,280-19,330, 27,653-38,590, and 30,635-32,185 mg kg-1 DM, respectively, in sprouts. Antioxidant activity ranged from 119,864 to 174,640 and 31,484 to 52,584 mg Trolox eq. kg-1 DM in buds and sprouts, respectively. Phenolic amount and profile were significantly affected by phenological stage and sampling location. Antioxidant activity was related to flavan-3-ol and hydroxycinnamic acid amount, and to non-phenolic substances. AlCl3-based method underestimated total phenolic content owing to lack of selectivity to important phenolic classes whereas Folin-Ciocalteau method was affected by non-phenolic interfering substances. HPLC-DAD proved to be more effective in determining hawthorn phenolics.