Polyphenol contents and antioxidant activities of extracts from flowers of two Crataegus azarolus L. varieties

Phenolic contents of the ethyl acetate extracts prepared from floral buds and opened flowers harvested on Crataegus azarolus trees native in two localities were performed. The antioxidant activity was measured by DPPH' (2,2-diphenyl-picrylhydrazyl), ABTS+ (2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals scavenging using spectrophotometric method. The C. azarolus var. aronia (Willd.) Batt., producing yellow fruits, was richer in total phenols (1638.7 +/- 89.9 mg acid gallic/100 g dry weight) according to C. azarolus var. eu-azarolus Maire (1415.5 +/- 23.8 mg acid gallic/100 g dry weight), producing red ones. Ethyl acetate extract from opened flowers has less content in total phenols, proanthocyanidins and flavonoids compared to this from floral buds. Floral buds from the two C. azarolus varieties occurring in Siliana-Djebel Serdj showed the highest radical scavenging activities (2431.8 +/- 32.7 and 2267.7 +/- 22.7 micromol Trolox/100 g dry weight). Hawthorn from Tunisia contains eight antioxidants of phenolic type (chlorogenic acid, hyperoside, rutin, spiraeoside, isoquercitrin, quercetin, (-)-epicatechin and the dimer procyanidin B2). These compounds identified specially in floral bud extracts presented a strong radical-scavenging activity.