Chemical analysis and biological activities of Populus nigra, flower buds extracts as source of propolis in Algeria

Seven fractions obtained by a selective extraction procedure from Populus nigra flower buds were examined for their antimicrobial and antioxidant properties, in vitro, using radical scavenging and inhibition of lipid peroxidation assays. The aqueous chloroform fraction that exhibited the best antioxidant activity was investigated for anti-inflammatory activity in vivo. Quantification of total phenolic compounds in these fractions was equally carried out. The results obtained with the aqueous fraction of chloroform were particularly interesting, being the most effective on DPPH (IC50 24.61 mu g/mL), ABTS (IC50=17.09 mu g/mL), NO (IC50=9.52 mu g/mL), HOCl (IC50 =187.90 mu g/mL) and OH- (IC50=113.79 mu g/mL) radicals in addition to exerting a high inhibition on both xanthine oxidase (XO) activity and lipoperoxydation (IC50=60.7 and 24.93 +/- 1.22 mu g/mL, respectively). Moreover, the same fraction (200 mg/kg) has equally demonstrated a potent anti-inflammatory potential (62.36%) in carrageenan-induced mice paw edema model. On the other hand, it is rather the organic extracts that exhibited the highest antimicrobial activity against tested microorganisms. Hence, these results suggest that P. nigra is a promising source of bioactive compounds that can be exploited as antioxidants and bactericidal in food products as well as in pharmaceutical therapeutic use. (C) 2014 Elsevier B.V. All rights reserved.