| Dihydrofolate reductase (DHFR) has become an important target for drug therapy because it is essential for the proliferation of pathogens or cancer cells. However, there has not been a study examining the combinination of triazines with a known DHFR inhibitor, trimethoprim. This study was conducted to examine the relationship of trimethoprim with 1,3,5-s-triazines. Combinations of trimethoprim and the 1,3,5-s-triazines were added to cultures of Lactobacillus rhamnosus and optical density measurements were taken. These measurements were used to estimate the fraction affected (fa), which is the inhibition of growth. The median dose (Dm) or I50 of trimethoprim for L. rhamnosus was established to be 0.395 microM. The fractions affected were used in calculation of mixed drug-effects to determine if there was an additive, synergistic, or antagonistic relationship. The mixed drug-effects were analyzed using a paired-t test and it was concluded that they were not significantly different from an additive effect. Therefore, neither a synergistic nor antagonistic relationship was displayed. |
