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

Therapeutic control of beta-lactamase-producing bacteria has been a major clinical problem. Development of drug combinations containing the beta-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 microM. 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.