This work describes the study of the antioxidant, antibacterial and anticoagulant effect of the methanolic extract of Rhaponticum acaule fruit (Asteracea family), also known as Lenzea acaulis L, is one of the aromatic plants from the beginning of spring flowering from March to May. This spontaneous plant develops in the north of Algeria and commonly called Tafgha. The antioxidant activity of the Rhaponticum acaule fruit was determined in vitro by the DPPH test; 1,1-diphenyl-2-picryl-hydrazyl, the obtained results showed that the extract had an effective DPPH scavenging activity with an IC50 value of 0.065 mg /ml. The fruit extract exhibited antibacterial activity against three strains of standard bacteria; Staphylococcus aureus, Escherichia coli and Enterococcus fecalis with a high inhibition zone diameter against Escherichia coli of 45 mm when the extract was diluted to 50%, Enterococcus of 13 mm and Staphylococcus of 19 mm for a crude and concentrated extract. The anticoagulant activity of the extract was evaluated in vitro on a displaced plasma by measuring two important parameters; the prothrombin level (PL) and International Normalized Ratio (INR). The results showed that the fruit can be used as a source of anticoagulant compounds to prevent arterial and venous tromboses if 25%, 50% and 75% diluted extracts are used (TP are respectively 38.4%, 33.5% and 24.5%, INR are 1.35, 2.71 and 3.83, respectively). For crude extract concentrated to 100%, it can cause haemorrhage.
