Antifolate studies. Activities of 40 potential antimalarial compounds against sensitive and chlorguanide triazine resistant strains of folate-requiring bacteria and Escherichia coli

Genther, Clara S.; Smith, Carl C.

doi:10.1021/jm00212a010

Cited by 28 publications

(6 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…P. cerevisiae, however, was less susceptible to aminopterin than the other lactobacilli, which is in accordance with the findings on methotrexate (9). Trimethoprim was an effective inhibitor in vitro, with the exception of P. cerevisiae.…”

Section: Methodssupporting

confidence: 90%

“…There are, however, remarkable exceptions: pyrimethamine and the isopropylpteridine are much more active in S. faecalis and also in L. arabinosus than was predicted from the enzymatic inhibition. The higher potency of pyrimethamine in comparison to trimethoprim was also observed by others (9). The high susceptibility of S. faecalis to pyrimethamine has been exploited for the microbiological determination of this compound (22).…”

Section: Discussionmentioning

confidence: 55%

“…P. cerevisiae is less susceptible to aminopterin than the other lactobacilli, despite similar h5o values of the enzymes. This is also true for methotrexate (9) and can be explained by the uptake properties of P. cerevisiae (15).…”

Section: Discussionmentioning

confidence: 79%

See 2 more Smart Citations

Dihydrofolate Reductases in Some Folate-Requiring Bacteria with Low Trimethoprim Susceptibility

Then

Riggenbach

1978

Antimicrob Agents Chemother

View full text Add to dashboard Cite

Dihydrofolate reductases from the folate-requiring strains Streptococcus faecalis ATCC 8043, Lactobacillus casei ATCC 7496, and Pediococcus cerevisiae ATCC 8081, as well as from Lactobacillus arabinosus, which is not dependent on exogenous folate, were isolated, and their properties were compared to reductases of Escherichia coli B, Staphylococcus aureus, and rat liver reductase. An inhibition profile with six different inhibitors revealed significant differences among all enzymes. All lactobacilli reductases are less sensitive to trimethoprim than the enzymeA of E. coli and S. aureus, the reductase of P. cerevisiae requiring a concentration at least 1,000 times higher for 50% inhibition. Inhibition of growth of S. faecalis by pyrimethanmine and 2,4-diamino-6,7-diisopropyl-pteridine was seen to be much stronger than was predicted from the enzymatic data.Strains such as Streptococcus faecalis, Pediococcus cerevisiae, and Lactobacillus casei are often used for evaluating and characterizing antifolate compounds (e.g., references 9, 10, and 21). They are unable to synthesize their own folate cofactors and require preformed folates or, as in the case of P. cerevisiae, reduced folates for growth. These strains are therefore also used for very sensitive assays of several folate compounds, as they differ in their ability to utilize particular derivatives. They are strongly inhibited by antifolate compounds such as methotrexate or aminopterin, which may be actively transported (14, 27). In P. cerevisiae, the uptake system has been shown to be not identical with that for the transport offolinate (13). The strains are of course resistant to sulfonamides which interfere with the biosynthesis of dihydrofolate at dihydropteroate synthetase.During work on dihydrofolate reductases (EC 1.5.1.3) of different bacteria, investigated as target sites for trimethoprim-like compounds, we also studied the reductases of some folate-requiring strains, since their folate auxotrophy suggested possible alterations in this enzyme as well. Dihydrofolate reductases from S. faecalis ATCC 8043 (syn. S. faecium var. durans), P. cerevisiae ATCC 8081, L. casei ATCC 7496, and L. arabinosus ATCC 8014, which, however, is not dependent on exogenous folate, were partially purified and their response to some structurally different inhibitors was compared to that of the enzymes from Escherichia coli B, Staphylococcus aureus, and also to rat liver enzyme as an example of an eucaryotic enzyme. Inhibition profiles, which have been successfully used for detecting subtle differences in dihydrofolate reductases of different origin (e.g., reference 6), revealed major differences in these enzymes. MATERIALS AND METHODSPropagation of celli. Cells were grown in batches of 200 ml up to 6 liters in either Erlenmeyer flasks under agitation or, in the case of the lactobacilli, without agitation. The following media were used: sensitivity test broth (Oxoid Ltd., London, England) for E. coli B, S. aureus, and S. faecalis; lactobacilli AOAC broth (Difco Laboratories, Detro...

show abstract

Section: Methodssupporting

confidence: 90%

Section: Discussionmentioning

confidence: 55%

See 1 more Smart Citation

Dihydrofolate Reductases in Some Folate-Requiring Bacteria with Low Trimethoprim Susceptibility

Then

Riggenbach

1978

Antimicrob Agents Chemother

View full text Add to dashboard Cite

show abstract

“…High‐throughput screening yielded relatively few active compounds belonging to Classes C, D and E. Compounds C‐101 and C‐103 have not been not reported as antibacterials, although a few related compounds have been reported to show antimicrobial and antimalarial properties (Davoll et al , 1972; Genther and Smith, 1977). For Class D compounds, the methoxy group in D‐101 and D‐102, or the cyclic ether group in D‐103 were necessary for antibacterial activity.…”

Section: Discussionmentioning

confidence: 99%

Small molecules with antimicrobial activity against E. coli and P. aeruginosa identified by high‐throughput screening

Fuente

Sonawane

Arumainayagam

et al. 2006

British J Pharmacology

115

View full text Add to dashboard Cite

Background and purpose: New antimicrobials are needed because of the emergence of organisms that are resistant to available antimicrobials. The purpose of this study was to evaluate a high-throughput screening approach to identify antibacterials against two common disease-causing bacteria, and to determine the frequency, novelty, and potency of compounds with antibacterial activity. Experimental approach: A high-throughput, turbidometric assay of bacterial growth in a 96-well plate format was used to screen a diverse collection of 150,000 small molecules for antibacterial activity against E. coli and P. aeruginosa. The statistical Z 0 -factor for the assay was X0.7. Key results: Screening for inhibition of E. coli growth gave a 'hit' rate (460% inhibition at 12.5 mM) of 0.025%, which was more than 5-fold reduced for P. aeruginosa. The most potent antibacterials (EC 50 o0.5 mM) were of the nitrofuran class followed by naphthalimide, salicylanilide, bipyridinium and quinoazolinediamine chemical classes. Screening of 4250 analogs of the most potent antibacterial classes established structure-activity data sets. Conclusions and Implications:Our results validate and demonstrate the utility of a growth-based phenotype screen for rapid identification of small-molecule antibacterials. The favourable efficacy and structure-activity data for several of the antibacterial classes suggests their potential development for clinical use.

show abstract

“…DHFR catalyzes the oxidation of NADPH and reduction of dihydrofolate to NADP and tetrahydrofolate, respectively (3), and its activity is required to replenish the reduced folate pool depleted by thymidylate biosynthesis during DNA replication. Subtle differences in the active sites of human and pathogen DHFR enzymes have made it possible to identify efficacious drugs that are potent and selective inhibitors of some pathogen DHFR enzymes without strongly affect-ing the human enzyme, thereby providing a high therapeutic index (3,5,14,16,27,38,63).…”

mentioning

confidence: 99%

Identification of Cryptosporidium parvum Dihydrofolate Reductase Inhibitors by Complementation in Saccharomyces cerevisiae

Brophy

Vásquez

Nelson

et al. 2000

Antimicrob Agents Chemother

View full text Add to dashboard Cite

There is a pressing need for drugs effective against the opportunistic protozoan pathogen Cryptosporidium parvum. Folate metabolic enzymes and enzymes of the thymidylate cycle, particularly dihydrofolate reductase (DHFR), have been widely exploited as chemotherapeutic targets. Although many DHFR inhibitors have been synthesized, only a few have been tested against C. parvum. To expedite and facilitate the discovery of effective anti-Cryptosporidium antifolates, we have developed a rapid and facile method to screen potential inhibitors of C. parvum DHFR using the model eukaryote, Saccharomyces cerevisiae. We expressed the DHFR genes of C. parvum, Plasmodium falciparum, Toxoplasma gondii, Pneumocystis carinii, and humans in the same DHFRdeficient yeast strain and observed that each heterologous enzyme complemented the yeast DHFR deficiency. In this work we describe our use of the complementation system to screen known DHFR inhibitors and our discovery of several compounds that inhibited the growth of yeast reliant on the C. parvum enzyme. These same compounds were also potent or selective inhibitors of the purified recombinant C. parvum DHFR enzyme. Six novel lipophilic DHFR inhibitors potently inhibited the growth of yeast expressing C. parvum DHFR. However, the inhibition was nonselective, as these compounds also strongly inhibited the growth of yeast dependent on the human enzyme. Conversely, the antibacterial DHFR inhibitor trimethoprim and two close structural analogs were highly selective, but weak, inhibitors of yeast complemented by the C. parvum enzyme. Future chemical refinement of the potent and selective lead compounds identified in this study may allow the design of an efficacious antifolate drug for the treatment of cryptosporidiosis.

show abstract

Antifolate studies. Activities of 40 potential antimalarial compounds against sensitive and chlorguanide triazine resistant strains of folate-requiring bacteria and Escherichia coli

Cited by 28 publications

References 8 publications

Dihydrofolate Reductases in Some Folate-Requiring Bacteria with Low Trimethoprim Susceptibility

Dihydrofolate Reductases in Some Folate-Requiring Bacteria with Low Trimethoprim Susceptibility

Small molecules with antimicrobial activity against E. coli and P. aeruginosa identified by high‐throughput screening

Identification of Cryptosporidium parvum Dihydrofolate Reductase Inhibitors by Complementation in Saccharomyces cerevisiae

Contact Info

Product

Resources

About