Evaluation des activités antioxydante et antibactérienne des extraits de Santolina chamaecyparissus

Abstract

The aim of this study is to evaluate antioxidant and antibacterial activities of aqueous (Aq.E) and methanolic (Met.E) extracts of Santolina chamaecyparissus, a medicinal plant from traditional pharmacopoeia of Algeria. Antioxidant activity was evaluated using the DPPH, chelation, β-caroten bleaching, linoleic acid peroxidation and reducing power tests. Firstly, polyphenols, flavonoids and tannins content was determined. Results showed that Met.E is rich in polyphenols, flavonoids and tannins with values of 105.88  11.67 µg EAG/mg, 20.99  6.08 µg EQ/mg and 114.82  13.39 µg EAT/mg respectively. These values are higher than that obtained with Aq.E. On the other hand, both extracts showed a very strong antiradical activity against DPPH radical, even higher than that of BHT. Moreover, Aq.E and Met.E exhibited a strong chelator activity with EC50 values of 61,47 ± 3, 93 µg/ml and 197,88 ± 33,47 µg/ml, respectively. These values are still lower than that of EDTA. In addition, Aq.E and Met.E inhibited the linoleic acid/β-caroten coupled peroxidation with 80% and 88% respectively. These values are close to that of standard antioxidants. Moreover, the extracts inhibited linoleic acid peroxidation with 66% and 64% respectively in linoleic acid peroxidation test. In addition, both extracts showed a strong concentration-dependant reducing power. Antibacterial effect of Aq.E and Met.E was evaluated by agar diffusion assay toward eight bacterial strains. Results revealed that Met.E exerted significant effect only on Enterococcus faecalis and Pseudomonas aeruginosa with inhibition zones of 8 mm et 8,5 mm respectively. In conclusion, Met.E of Santolina chamaecyparissus has an excellent antioxidant activity and a weak antibacterial one, while Aq.E exerts a very strong antioxidant effect and none antibacterial one.