The Effect of Harvesting Time on the Antibacterial Activity of Salvia leriifolia Benth. Leaf extract

Salvia leriifolia (Lamiaceae) is an endemic plant of Khorasan and Semnan provinces which has antinociceptive, anti-inflammatory, antidiabetic and antioxidant properties. In this research, antibacterial activity of of S. leriifolia leaf was investigated at different growth stages and the best harvesting time was determined. The leaves were harvested at vegetative (mid March), flowering (mid April) and ripening seed stages (late May). Different concentrations of metanolic extract(5,10,15 and 20 g/l) of leaves were applied on five different bacteria(Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis) according to dick diffusion method. Inhibition zones were measured after 24 hours. Inhibitory effect of extracts at different stages were compared together and with certain antibiotics (Penicillin, Ampicilin and Tetracaiclin). Statistical analysis was performed through the JMP software. Maximum antibacterial activity of leaves was coincident with flowering stage. In this stage, antibacterial activity of leaves was significantly higher than the vegetative and ripening seed stage. Inhibitory effect of leaf extract at flowering stage on some bacteria was higher than the antibiotics or similar with them. It seems that flowering stage (mid April) is the best time for obtaining the maximum antioxidant activity of leaf.