Beta-lactamase inhibitory component from the roots of Fissistigma cavaleriei.

Abstract Therapeutic control of β-lactamase-producing bacteria has been a major clinical problem. Development of drug combinations containing the β-lactamase inhibitors has given clinicians a novel approach to controlling resistant organisms. In our search for beta-lactamase inhibitors from natural resources, we found that the methanol extract of the roots of Fissistigma cavaleriei showed an inhibitory effect on beta-lactamase. Bioassay-guided isolation of the extract yielded an active compound that was identified as salicylsalicylic acid by physical and spectroscopic methods. The compound showed inhibitory effects on beta-lactamase in a dose-dependent manner with IC 50 values of 71 μM. Salicylsalicylic acid is not as potent as the original inhibitors such as clavulanic acid, but it may be developed to be potent beta-lactamase inhibitor by chemical modification.