Résumé:
Ammi visnaga (L) is a species from Apiaceae family (Umbelliferae), it is widely used in Algeria. It is supposed to be an interesting source of phenolic compounds which can be used against biofilm growth of bacteria. Bacillus cereus, a crucial pathogenic bacterium that causes food poisoning, is known as a producer of gastrointestinal diseases. In the present work we used water, acetone, ethanol and methanol to extract phenolic compound from the plant Ammi visnaga (L). The extracts were evaluated for their antioxidant activity and their effects on planktonic cells, swarming motility and biofilm growth of Bacillus cereus isolates. The results indicate that 70% methanolic extract represent the highest amount of total phenols (176mg GAE/g), and the lowest amount was obtained with acetone extract (18, 66mg GAE/g). Flavonoids extractability was found to be highest with ethanolic extract (22mg QE/g). Among all the extracts of A. visnaga (L), methanolic extract 70% showed the most potent radical scavenging ability (IC 50: 1, 46mg/ml) and the highest reducing power values from 1,129 to 1,974 at 700nm. DPPH assay of plant extracts was well correlated with FRAP assay (R2=0, 7018) and a good
correlation was found between antioxidant activity (IC 50) and polyphenols content of different extracts (R2=0, 8153). No correlation was found between total polyphenol and flavonoids contents (R2=0, 4267). The obtained results show that A. visnaga (L) extracts might possess high antimicrobial activities and methanolic extract at 10mg/ml was more effective to swarming motility and biofilm formation in Bacillus cereus strains.
