Nitrocefin assay with purified β-lactamase. We compared nitrocefin hydrolysis of purified β-lactamase blend (Sigma, catalog # L7920) in the presence of chemicals 1, 2, and 3. Pure β-lactamase at a concentration of 1 mg/mL was serially diluted. Each well was then combined with either DMSO or chemical (1, 2, or 3). Nitrocefin was added at a concentration of 500 µg/mL and the solutions were incubated at room temperature for 2-3 minutes. Color changes were recorded at 486 nm to determine any direct inhibitory effect of these chemicals on purified β-lactamase. The data reported in this manuscript corresponds to the lowest concentration we tested, to ensure maximum opportunity for inhibition by the chemicals.