83166-73-8Relevant academic research and scientific papers
Inhibitor design to target a unique feature in the folate pocket of Staphylococcus aureus dihydrofolate reductase
Muddala, N. Prasad,White, John C.,Nammalwar, Baskar,Pratt, Ian,Thomas, Leonard M.,Bunce, Richard A.,Berlin, K. Darrell,Bourne, Christina R.
, (2020)
Staphylococcus aureus (Sa) is a serious concern due to increasing resistance to antibiotics. The bacterial dihydrofolate reductase enzyme is effectively inhibited by trimethoprim, a compound with antibacterial activity. Previously, we reported a trimethoprim derivative containing an acryloyl linker and a dihydophthalazine moiety demonstrating increased potency against S. aureus. We have expanded this series and assessed in vitro enzyme inhibition (Ki) and whole cell growth inhibition properties (MIC). Modifications were focused at a chiral carbon within the phthalazine heterocycle, as well as simultaneous modification at positions on the dihydrophthalazine. MIC values increased from 0.0626–0.5 μg/mL into the 0.5–1 μg/mL range when the edge positions were modified with either methyl or methoxy groups. Changes at the chiral carbon affected Ki measurements but with little impact on MIC values. Our structural data revealed accommodation of predominantly the S-enantiomer of the inhibitors within the folate-binding pocket. Longer modifications at the chiral carbon, such as p-methylbenzyl, protrude from the pocket into solvent and result in poorer Ki values, as do modifications with greater torsional freedom, such as 1-ethylpropyl. The most efficacious Ki was 0.7 ± 0.3 nM, obtained with a cyclopropyl derivative containing dimethoxy modifications at the dihydrophthalazine edge. The co-crystal structure revealed an alternative placement of the phthalazine moiety into a shallow surface at the edge of the site that can accommodate either enantiomer of the inhibitor. The current design, therefore, highlights how to engineer specific placement of the inhibitor within this alternative pocket, which in turn maximizes the enzyme inhibitory properties of racemic mixtures.
Halogenated trimethoprim derivatives as multidrug-resistant Staphylococcus aureus therapeutics
Nilchan, Napon,Phetsang, Wanida,Nowwarat, Taechin,Chaturongakul, Soraya,Jiarpinitnun, Chutima
, p. 5343 - 5348 (2018/05/25)
Incorporation of halogen atoms to drug molecule has been shown to improve its properties such as enhanced in membrane permeability and increased hydrophobic interactions to its target. To investigate the effect of halogen substitutions on the antibacterial activity of trimethoprim (TMP), we synthesized a series of halogen substituted TMP and tested for their antibacterial activities against global predominant methicillin resistant Staphylococcus aureus (MRSA) strains. Structure-activity relationship analysis suggested a trend in potency that correlated with the ability of the halogen atom to facilitate in hydrophobic interaction to saDHFR. The most potent derivative, iodinated trimethoprim (TMP-I), inhibited pathogenic bacterial growth with MIC as low as 1.25 μg/mL while the clinically used TMP derivative, diaveridine, showed resistance. Similar to TMP, synergistic studies indicated that TMP-I functioned synergistically with sulfamethoxazole. The simplicity in the synthesis from an inexpensive starting material, vanillin, highlighted the potential of TMP-I as antibacterial agent for MRSA infections.
Synthesis and biological activity of substituted 2,4-diaminopyrimidines that inhibit Bacillus anthracis
Nammalwar, Baskar,Bunce, Richard A.,Berlin, K. Darrell,Bourne, Christina R.,Bourne, Philip C.,Barrow, Esther W.,Barrow, William W.
, p. 387 - 396 (2012/10/08)
A series of substituted 2,4-diaminopyrimidines 1 has been prepared and evaluated for activity against Bacillus anthracis using previously reported (±)-3-{5-[(2,4-diamino-5-pyrimidinyl)methyl]-2,3-dimethoxyphenyl} -1-(1-propyl-2(1H)-phthalazinyl)-2-propen-1-one (1a), with a minimum inhibitory concentration (MIC) value of 1-3 μg/mL, as the standard. In the current work, the corresponding isobutenyl (1e) and phenyl (1h) derivatives displayed the most significant activity in terms of the lowest MICs with values of 0.5 μg/mL and 0.375-1.5 μg/mL, respectively. It is likely that the S isomers of 1 will bind the substrate-binding pocket of dihydrofolate reductase (DHFR) as in B. anthracis was found for (S)-1a. The final step in the convergent synthesis of target systems 1 from (±)-1-(1-substituted-2(1H)- phthalazinyl)-2-propen-1-ones 6 with 2,4-diamino-5-(5-iodo-3,4-dimethoxybenzyl) pyrimidine (13) was accomplished via a novel Heck coupling reaction under sealed-tube conditions.
Preliminary in vitro studies on two potent, water-soluble trimethoprim analogues with exceptional species selectivity against dihydrofolate reductase from Pneumocystis carinii and Mycobacterium avium
Forsch, Ronald A.,Queener, Sherry F.,Rosowsky, Andre
, p. 1811 - 1815 (2007/10/03)
2,4-Diamino-5-[3′,4′-dimethoxy-5′-(5-carboxy-1-pentynyl)] benzylpyrimidine (6) and 2,4-diamino-5-[3′,4′-dimethoxy-5′-(4- carboxyphenylethynyl)benzylpyrimidine (7) were synthesized from 2,4-diamino-5-(5′-iodo-3′,4′-dimethoxybenzyl)pyrimidine (9) via a Sonogashira reaction with appropriate acetylenic esters followed by saponification, and were tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat in comparison with the widely used antibacterial agent 2,4-diamino-5-(3′,4′,5′-trimethoxybenzyl)pyrimidine (trimethoprim, TMP). The selectivity index (SI) for each compound was calculated by dividing its 50% inhibitory concentration (IC50) against rat DHFR by its IC50 against Pc, Tg, or Ma DHFR. The IC 50 of 6 against Pc DHFR was 1.0 nM, with an SI of 5000. Compound 7 had an IC50 of 8.2 nM against Ma DHFR, with an SI of 11000. By comparison, the IC50 of TMP was 12000 nM against Pc, 300 nM against Ma, and 180000 against rat DHFR. The potency and selectivity values of 6 and 7 were not as high against Tg as they were against Pc or Ma DHFR, but nonetheless exceeded those of TMP. Because of the outstanding selectivity of 6 against Pc and of 7 against Ma DHFR, these novel analogues may be viewed as promising leads for further structure-activity optimization.
