SYNERGISM OF ISOPTEROPODINE AND PTEROPODINE WITH ANTIBIOTICS AGAINST SELECTED STREPTOCOCCI

Abstract

We have previously reported the isolation of four compounds from Malaysian Uncaria tomentosa. In view of the lack of specific antibacterial studies reported on the isolated compounds, this study was undertaken to evaluate its antibacterial potential against selected Streptococcus species. The antibacterial activity of phytochemicals (isopteropodine and pteropodine) as well as antibiotics (amoxicillin, cephradine, cloxacillin, oxacillin and penicillin) was evaluated with three oral bacteria (Streptococcus mitis, Streptococcus mutans and Streptococcus oralis). In addition, the possible synergistic effects when associated with antibiotics were studied. For the antibacterial assay, the agar-well diffusion method has been employed. The antibacterial activity was expressed as the average diameter of the clear zone inhibition of bacterial growth around the well. The minimum inhibitory concentration (MIC) of the compounds and antibiotics was determined by broth microdilution assay utilizing 96 well microtitre plate. For the synergistic activity, checkerboard assay has been employed. In this study, only isopteropodine was found to be active against S. mutans with inhibition zone of 13 mm. No growth inhibition was found on pteropodine. Upon MIC determination, the isopteropodine was found to show strong inhibitory properties against S. mutans with MIC value of 31.25 mg/mL. Association of antibiotics and isopteropodine showed synergistic antibacterial activity against S. mutans. The FICs values obtained by Checkerboard Assay were 0.09 for all tested combinations.