Effect of colloidal silver concentrate on the antibacterial activity of ethanolic extract of lichen Parmella perlate

The antibacterial activity of the ethanolic extract of the lichen Parmelia perlata in combination with colloidal silver concentrate was assessed in vitro against Staphylococcus aureus by the diameter of inhibitory activity using the agar- well diffusion technique. The ethanolic extract of the lichen was active against the test organism with an MIC of 5.0 mg/ml, while colloidal silver concentrate was inactive at the concentrations tested. Antibacterial activity of the extract increased two fold in the presence of colloidal silver concentrate with an MIC of 7.94 mg/ml, and a corresponding fractional inhibitory concentration, FIC index of 0.58 mg/ml, resulting in a relative potency of 1.58 mg/ml. These parameters therefore indicate a potentiating effect by colloidal silver concentrate on the antibacterial activity of the lichen. Keywords : Colloidal Silver Concentrate, antibacterial activity, ethanolic-extract, Lichen Parmelia perlata , antimicrobial, drugcombination, synergistic effect Journal of Pharmaceutical and Allied Sciences , Vol. 7 No. 3 (2010)