Panel A), metal analysis of equisetin-treated S. aureus S. aureus culture was added to LB broth, with DMSO or EQI (IC90; 4.36 μM). Cultures were incubated at 37°C for 2 hours, digested in nitric acid (trace metal grade) and analyzed by ICP-OES. Total metal concentrations were adjusted based on final OD600. Co, Cd, Ni, Ag, & Se total metal concentrations < Limit of Detection. Mean ± SEM, n = 11. *p<0.05; **p<0.005 (Student’s t-test). Panel B),
S. aureus cultures were incubated in DMSO or EQI (IC90; 4.36 μM) in the presence or absence of exogenous metals. Metal solutions (MgCl, MnCl, & Fe(EDTA)) were: 1 μM, 10 μM, and 100 μM. Percent survival determined by the MTT assay. Mean ± SEM, n = 6. *p<0.05 (Student’s t-test).