Etude comparative des propriétés antioxydantes et antimicrobiennes d’extraits d'une plante médicinale obtenus par méthodes d'extraction classique et moderne

Abstract

Rhamnus alaternus is one of the most widely used plants in the Mediterranean basin, due to its benefits, particularly in the treatment of liver complications, jaundice and certain dermatological conditions. This study focuses on comparing the antioxidant and antimicrobial properties of extracts from the aerial part (leaves) of the Rhamnus alaternus species, obtained by three extraction methods: conventional maceration, ultrasound-assisted maceration, microwave-assisted maceration. Extraction yields differed from one process to another: 40.15; 51.70; 81.35 (%) for conventional maceration, microwave-assisted maceration and ultrasonic-assisted maceration, respectively. The ultrasound-assisted extract was the richest in total polyphenols (169.54 mg EAG /g M.S) and total flavonoids (13.34 mg EQ /g M.S), followed by the microwave-assisted extract (165.05 mg EAG /g M.S in total polyphenols and 9.05 mg EQ /g M.S in total flavonoids). The lowest content of bioactive compounds was recorded by the extract obtained by maceration with a value equal to 143.57mg EAG /g M.S in total polyphenols and 6 EQ /g M.S in total flavonoids. Antioxidant activity testing using the DPPH method revealed significant antioxidant power for all three extracts, although that corresponding to the extract obtained from microwave-assisted maceration was the highest with an IC50 value equal to 0.010(mg/ml), followed by that of the extract obtained from ultrasound application 0.026(mg /ml), which is almost equal to that obtained for conventional maceration 0.024(mg/ml). Antibacterial activity on two strains: Staphylococcus and Escherichia coli, gave a remarkable result on the plant's antibacterial activity. The inhibition rate in the antifungal test was 0% for the extract obtained by maceration, 3% for the extract obtained using the ultrasound-assisted technique and 12.62% for the extract obtained using the microwave technique. Key words: Rhamnus alaternus,