Antimicrobial and antioxidant properties of Betula aetnensis Rafin. (Betulaceae) leaves extract.

This study aimed to evaluate the antimicrobial effects, the radical scavenging activity (by DPPH and ABTS tests) and the antioxidant capacity (by β-carotene bleaching test) of Betula aetnensis leaves extract. The antimicrobial activity was tested against 14 Gram-positive clinical strains, 2 ATCC Gram-positive strains, 10 Gram-negative clinical strains and 4 Gram-negative ATCC strains. Streptococcus pyogenes Ery-S and Ery-R1 were the most sensitive. Betula aetnensis was considerably active against three bacterial strains, namely Haemophilus influenzae ATCC 49247, Amp-R1 and Moraxella catarrhalis ATCC 25238. Standard ATCC strains of Gram-positive bacteria were more sensitive than Gram-negative. Betula aetnensis showed also an interesting reducing power with TEAC values of 9.7 and a good inhibition of linoleic acid oxidation with an IC50 value of 22.0 µg mL(-1) after 30 min of incubation. The total phenol and flavonoid contents were determined with the purpose to evaluate the relationship with the observed bioactivities.