Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FOLIC ACID ANTAGONISTS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources
PubMed2003

Novel antifolate drugs.

Antimetabolites are active chemotherapeutic agents for many solid tumor and hematologic malignancies. Folate antagonists, purine analogues, and pyrimidine analogues are the three main categories of antimetabolites. Methotrexate, the most studied folate antagonist, is effective in many malignancies. Methotrexate inhibits dihydrofolate reductase, which leads to accumulation of polyglutamated folates, causing further inhibition of thymidylate synthase and glycinamide ribonucleotide formyltransferase. Subsequently, the lack of reduced folate substrates impairs synthesis of purine nucleotides, thymidylate, and certain amino acids, which can lead to cell death. However, methotrexate resistance develops through several mechanisms, including decreased folate carrier-mediated membrane transport, dihydrofolate reductase gene amplification, specific transcription-translational modifications, and downregulation of intracellular methotrexate polyglutamation. Antifolate drug development has focused on agents designed to overcome different aspects of methotrexate resistance. This article reviews the enzymatic targets for antifolates, describes the known mechanisms of antifolate resistance, and summarizes the current development of novel antifolate agents. Discussed specifically are trimetrexate, edatrexate, raltitrexed, pemetrexed, ZD9331, lometrexol, LY309887, GW1843, OSI-7904(L), and nolatrexed, all of which have unique clinical pharmacology and are in various stages of development. The toxicity of antifolates has been sporadic and difficult to predict clinically. Supplementation with folic acid and vitamin B(12) has been shown to reduce the toxicity of pemetrexed without affecting efficacy and has increased the therapeutic index for this novel agent.

Antimetabolites, Antineoplastic↗
PubMed1984

Effects of three new folate antagonists on human breast adenocarcinoma cells in vitro and on immune responses in vivo.

The effects of three selected potential folate antagonists on 3H-leucine incorporation of eight established breast adenocarcinoma cell lines were investigated. The compounds studied were 5,8-dideazaisofolic acid, 5-methyl-5,8-dideazaisofolic acid, and 10-oxa-5,8-dideazafolic acid. All three anti-folates were inhibitory to most of the cells tested. 10-Oxa-5,8-dideazafolic acid was more effective in inhibiting the growth of these tumor cell lines. Both natural killer cell activity and phytohemagglutinin (PHA)-induced lymphocyte proliferation were decreased in hamsters injected with these compounds, with 5,8-dideazaisofolic acid being the most potent in this regard. The natural killer cell activity and lymphocyte proliferation returned to normal levels 12 days post-injection of these compounds. These studies suggest that 10-oxa-5,8-dideazafolic acid may be useful for the treatment of human breast tumors.

Adenocarcinoma↗
PubMed1994

The activity of PS-15 in combination with sulfamethoxazole.

PS-15 is a novel biguanide folate antagonist that is metabolized in vivo to WR99210, a metabolite that is extremely active in vitro against multi-drug resistant strains of Plasmodium falciparum. When PS-15 was administered in combination with sulfamethoxazole to healthy Saimiri sciureus monkeys, the serum antimalarial activity was considerably greater than that observed in monkeys that received PS-15 alone. Further studies should be carried out to determine the value of PS-15/sulfonamide combinations in the treatment of human malaria infections and in preventing the emergence of drug-resistant parasites.

Animals↗
PubMed1981

Folate antagonists. 19. Synthesis and antimalarial effects of 6-(arylthio)-2,4-pteridinediamines.

A series of 6-(arylthio)-2,4-pteridinediamines (IIIa) was prepared by allowing 6-chloro-2,4-pteridinediamine to react with the requisite benzenethiols in dimethyl sulfone at 190-200 degrees C. Attempts at oxidation to the corresponding sulfoxide (IIIb) or sulfone (IIIc) were unsuccessful. The compounds exhibited a spectrum of antibacterial activity similar to, but below the potency of, the related quinazolinediamines and pteridinediamines. Unlike these related types, however, they were devoid of antimalarial activity when tested against a normal drug-sensitive strain of Plasmodium berghei in mice by the parenteral route.

Animals↗
PubMed1983

Folate antagonists. 20. Synthesis and antitumor and antimalarial properties of trimetrexate and related 6-[(phenylamino)methyl]-2,4-quinazolinediamines.

A series of 6-[(arylamino)methyl]-2,4-quinazolinediamines have been prepared by catalytic hydrogenation of the requisite 2,4-diamino-6-quinazolinecarbonitriles in the presence of the appropriate benzenamine. Formylation, acetylation, and nitrosation provided N omega derivatives of these compounds. A variety of the compounds exhibited potent antimalarial, antibacterial, and antitumor activity. In particular, 5-methyl-6-[[(3,4,5-trimethoxyphenyl)-amino]methyl]-2, 4-quinazolinediamine (trimetrexate, 15) has shown a broad spectrum of antitumor effects and is undergoing preclinical toxicology evaluation prior to trial in man.

Animals↗
PubMed1984

Folate antagonists. 22. Antimalarial and antibacterial effects of 2,4-diamino-6-quinazolinesulfonamides.

The synthesis and antimalarial activity of a series of 2,4-diamino-6-quinazolinesulfonamides (III) is described. Chlorosulfonation of 2,4-quinazolinediamine affords the 6-sulfonyl chloride, which upon treatment with the appropriate amine produces the desired products. Alternatively the sulfonyl chloride could be introduced by diazotization of the corresponding amine followed by treatment with SO2 in the presence of CuCl2. Although substantial antimalarial activity was demonstrated for several members of this class, studies were discontinued in light of the potency of related series.

Anti-Bacterial Agents↗
PubMed1982

Toxicity and anticancer activity of a new triazine antifolate (NSC 127755).

A new triazine folate antagonist, 3-chloro-4-((4-(2-chloro-4-[4,6-diamino-2,2-dimethyl-s-triazin-1(2H)-yl]phenyl)butyl)) benzenesulfonyl fluoride compounded with ethanesulfonic acid (1:1) (NSC 127755), was highly active against four transplantable colon adenocarcinomas (36, 38, 10/A, 12/A) and the Dunning murine ovarian tumor M5076. Treatment schedule studies indicated that a prolonged time of exposure provided optimum antitumor activity for the compound. The combination of NSC 127755 plus 4-amino-1-[5-O-(1-oxohexadecyl)-beta-D-arabinofuranosyl]-2(1H)-pyrimidinone (palmO-ara-C, NSC 135962) was found to have therapeutic synergism against grossly evident colon adenocarcinoma 36.

Acetamides↗
PubMed1987

Inhibition of human liver folylpolyglutamate synthetase by non-gamma-glutamylatable antifolate analogs.

Folylpolyglutamate synthetase (FPGS) catalyzes the gamma-glutamylation of both folates and folate antagonists and has been found to be essential for the survival of mammalian cells. Twelve analogs of the antifolates aminopterin (AMT) and methotrexate (MTX) having the -(CH2)2COOH moiety replaced by -(CH2)nX, where X = SO3H,PO3H2 or NH2, were evaluated as inhibitors of FPGS isolated from human liver. The AMT analogs were consistently found to be better inhibitors than their MTX counterparts, following the order of Km values determined for the parent antifolates as FPGS substrates. For the amino and phosphonate (but not for the sulfonate) compounds, inhibitory efficiencies were markedly dependent on the methylene chain length, with the most effective inhibitors having the groups -(CH2)3NH2(Ki = 0.2 microM) and -(CH2)2PO3H2 (Ki = 1.9 microM). Of those compounds exhibiting Ki values less than 200 microM, six were competitive inhibitors whereas three showed mixed inhibition (Ki' = approximately 6 Ki) when analyzed using AMT as the variable substrate. This demonstration of mixed inhibition of FPGS is consistent with the binding of inhibitor to a second site on the enzyme. Very similar Ki values (0.2-0.3 microM) were obtained for the -(CH2)3NH2 analog of AMT when using folic acid, AMT, MTX, and gamma-glutamyl-MTX as variable substrates, suggesting that the same enzymatic site on FPGS is active in the gamma-glutamylation of these four folyl derivatives. These findings serve to identify structural features which are important for inhibition of human liver FPGS and may therefore prove useful for the design of new compounds having potential as chemotherapeutic agents.

Amines↗
PubMedDate not supplied

Consensus scoring criteria for improving enrichment in virtual screening.

MOTIVATION: Virtual screening of molecular compound libraries is a potentially powerful and inexpensive method for the discovery of novel lead compounds for drug development. The major weakness of virtual screening-the inability to consistently identify true positives (leads)-is likely due to our incomplete understanding of the chemistry involved in ligand binding and the subsequently imprecise scoring algorithms. It has been demonstrated that combining multiple scoring functions (consensus scoring) improves the enrichment of true positives. Previous efforts at consensus scoring have largely focused on empirical results, but they have yet to provide a theoretical analysis that gives insight into real features of combinations and data fusion for virtual screening. RESULTS: We demonstrate that combining multiple scoring functions improves the enrichment of true positives only if (a) each of the individual scoring functions has relatively high performance and (b) the individual scoring functions are distinctive. Notably, these two prediction variables are previously established criteria for the performance of data fusion approaches using either rank or score combinations. This work, thus, establishes a potential theoretical basis for the probable success of data fusion approaches to improve yields in in silico screening experiments. Furthermore, it is similarly established that the second criterion (b) can, in at least some cases, be functionally defined as the area between the rank versus score plots generated by the two (or more) algorithms. Because rank-score plots are independent of the performance of the individual scoring function, this establishes a second theoretically defined approach to determining the likely success of combining data from different predictive algorithms. This approach is, thus, useful in practical settings in the virtual screening process when the performance of at least two individual scoring functions (such as in criterion a) can be estimated as having a high likelihood of having high performance, even if no training sets are available. We provide initial validation of this theoretical approach using data from five scoring systems with two evolutionary docking algorithms on four targets, thymidine kinase, human dihydrofolate reductase, and estrogen receptors of antagonists and agonists. Our procedure is computationally efficient, able to adapt to different situations, and scalable to a large number of compounds as well as to a greater number of combinations. Results of the experiment show a fairly significant improvement (vs single algorithms) in several measures of scoring quality, specifically "goodness-of-hit" scores, false positive rates, and "enrichment". This approach (available online at http://gemdock.life. nctu.edu.tw/dock/download.php) has practical utility for cases where the basic tools are known or believed to be generally applicable, but where specific training sets are absent.

Algorithms↗
PubMed1985

A selective N-methyl-D-aspartate antagonist depresses epileptiform activity in rat hippocampal slices.

The sensitivity of convulsant-induced epileptiform activity in the hippocampus to the selective N-methyl-D-aspartate (NMDA) antagonist D-2-amino-5-phosphonovalerate (D-APV) was examined using in vitro electrophysiological techniques. This compound reduced the number and size of the synaptically evoked population spikes recorded in the CA1 region in the presence of the convulsants, pentylenetetrazol, bicuculline or folate. Intracellular recordings in the presence of bicuculline showed that D-APV reduced the late component of the excitatory postsynaptic potential and the number of action potentials evoked synaptically. A mechanism is suggested to explain how NMDA receptors, which are known not to be involved in normal synaptic transmission in hippocampal slices, can contribute to epileptiform activity.

2-Amino-5-phosphonovalerate↗
PubMed1977

Reduced forms of aminopterin and methotrexate in L1210 lymphoma.

We examined several characteristics of reduced forms of folate antagonists. Dihydro and tetrahydro derivatives of aminopterin and methotrexate (MTX) were chemically prepared. When titrated with dihydrofolate reductase, reduced derivatives were equipotent with the parent compounds and titrated stoichiometrically with the enzyme at pH 6 and nonstoichiometrically at higher pH conditions (pH 7.4 and above). When incubated with L1210 cells in vitro, rates of uptake of tritiated reduced compounds were significantly less in L1210 and L1210/MTX cells compared with the respective oxidized parent compounds and significantly less in L1210/MTX than in L1210 cells. Although dihydroaminopterin and tetrahydromethotrexate increased the survival rate of mice bearing L1210 tumors, these compounds had no such effect on the life-spans of animals with L1210/MTX tumors.

Aminopterin↗
PubMed1978

Folate antagonists. 11. Synthesis and antimalarial effects of 6-[(aryloxy- and arylthio-)methyl]-2,4-pteridinediamines and -pteridinediamine 8-oxides.

Condensation of 3-amino-6-(bromomethyl)-2-pyrazinecarbonitrile 4-oxide with 4-chlorophenol gave 3-amino-6-[(4-chlorophenoxy)methyl]-2-pyrazinecarbonitrile 4-oxide (1), which was deoxygenated to obtain the de-N-oxide 4. Cyclization of 4 and 1 produced 6-[(4-chlorophenoxy)methyl]-2,4-pteridinediamine and the 8-oxide, respectively. 6-[(Arylthio)methyl]-2,4-pteridinediamines and their 8-oxides were produced analogously. Controlled oxidation of the former gave the anticipated sulfoxide 12 and sulfone 13. None of these compounds showed significant activity when tested against lethal Plasmodium berghei infections in mice or a select list of bacteria in vitro.

Animals↗
PubMed1975

Kinetics and mechanisms of action of 'folate synthesis inhibitors', alone or in combination, on Escherichia coli. III. Pyrimethamine, trimethoprim and sulfamethoxazole.

The inhibitory activity of pyrimethamine (PMA) is 1/290 of the activity of trimethoprim (TMP) against E. coli as evaluated from a plot of C.ko/ko-kapp VS. C. Even at high concentrations the effect of PMA in contrast to TMP seems to be cateriostatic. Combinations of TMP and PMA reveal an additive effect. In PMA-treated cultures, the slope of the logarithmic growth curve decreases after an initial inhibited growth, and a second steady state is established. This second steady state has a different reason than the one observed in TMP-treated cultures; whereas the second phase in TMP-inhibited cultures depends on the number of germs, in the case of PMA it depends on the number of generations. Using prewashed cell cultures, it was shown that there is no influence on the two steady states in PMA-inhibited cultures; for TMP, however, it was shown that the presence of the first phase is due to an antagonist excreted into the culture medium. These observations hint at differences in the mode of action of TMP and PMA in addition to differences in the affinity to the target enzyme dihydrofolate reductase. Combination of PMA with sulfamethoxazole (SMZ) at concentrations where both drugs are acting only bacteriostatically leads to effects considerably greater than would be expected from simple additivity. The kill rate observed is the same as observed for TMP/SMZ combinations despite of the considerable lower activity of PMA and SMZ. The results support the assumption that it might be possible to select drug combinations considering the best pharmacokinetical fit and not necessarily the most effective drugs in the series studied.

Cell Count↗
PubMed2000

Anti-arthritic effect of methotrexate: is it really mediated by adenosine?

The mechanism of action for the anti-arthritic effect of methotrexate (MTX) was investigated in rats with antigen-induced arthritis (AIA). Arthritis intensity was quantified as area under the curve (AUC) for the joint swelling. The response to MTX was in several respects similar to what is seen in the clinic. The drug reduced the AUC in a dose-dependent manner after oral weekly (2-4 mg/kg/week) or daily (0.3 mg/kg/day) dosing. This effect was not affected by supplementation with an equal dose of folate. The model thus seemed suitable for this type of study. Supplementation with folate in excess abolished the effect of MTX. A structurally similar antifolate, aminopterin, also reduced the arthritis. The effect thus seemed to be due to folate antagonism although a complete inhibition of dihydrofolate reductase (DHFR) might not be essential. Hence, it could be that the main target is a process downstream of DHFR. It has been proposed that inhibition of AICAR-transformylase induce the release of adenosine with anti-inflammatory properties. Here the adenosine antagonist R-PIA reduced the arthritis but when MTX was combined with adenosine antagonists no attenuation of the anti-arthritic effect was seen. On the contrary, three adenosine agonists (8-p-sulphophenyltheophyllamine 30 mg/kg i.p. twice daily; 3,7-dimethyl-1-propargylxanthine, p.o. 3 mg/kg/day and 8-cyclopentyl-1,3-dipropylxanthine, 1.5 mg/kg/day p.o.) potentiated MTX. The specific thymidylate synthase inhibitor 5-fluourouracil (0. 3-3.0 mg/kg/day) had no anti-arthritic effect. Neither did our data support the hypotheses that syntheses of polyamines or cytokines were primary targets. It is thus possible that the mechanism of action is inhibition of a process downstream of DHFR but the release of adenosine seems not to be important.

Adenosine↗
PubMed1998

Schedule-dependent synergism and antagonism between paclitaxel and methotrexate in human carcinoma cell lines.

Paclitaxel and methotrexate are active against a variety of solid tumors. Because of differences in their mechanisms of action and toxicity profiles, the combination of these two agents has clinical potential. Clinical studies of this combination are in progress. We studied the optimal schedule of paclitaxel and methotrexate in combination at various schedules in vitro using human lung cancer A549, breast cancer MCF7, ovarian cancer PA1, and colon cancer WiDr cells. Cells were simultaneously exposed to paclitaxel and methotrexate for 24 h and sequentially exposed to paclitaxel for 24 h followed by methotrexate for 24 h or vice versa. Cell growth inhibition after 5 days was determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of drug combinations at the concentration of drug that produced 80% cell growth inhibition (the IC80 level) were analyzed by the isobologram method. The simultaneous exposure to paclitaxel and methotrexate produced additive to antagonistic effects in the A549 and PA1 cells, and antagonistic effects in the MCF7 and WiDr cells. The sequential exposure to paclitaxel followed by methotrexate produced additive effects in all four cell lines. The reverse sequence produced synergistic effects in the A549, MCF7, and WiDr cells, and additive effects in the PA1 cells. These findings suggest that a sequential administration of methotrexate followed by paclitaxel may be the appropriate schedule for this combination. On the basis of the observed in vitro synergism, further in vivo and clinical studies are necessary to clarify the toxicity and proposed antitumor effects of this schedule.

Antineoplastic Agents, Phytogenic↗
PubMed1985

Overcoming methotrexate resistance by a lipophilic antifolate (BW 301U): from theory to models to practice.

We have provided a rationale for the clinical use of a new lipid-soluble folate antagonist, BW 301U, in terms of its potential for killing several classes of methotrexate-resistant cells. As part of a Phase I evaluation of this agent we studied normal bone marrow from cancer patients and their metabolic susceptibility to either BW 301U or to MTX and then repeated the observations at the end of five days of BW 301U infusions. Both inhibitors were roughly comparable at equimolar concentrations prior to therapy, but a relative resistance developed to MTX after BW 301U treatment. Such findings were replicated in an in vitro HL-60 cell culture system that was exposed to BW 301U. Some possible mechanisms for this unusual collateral resistance are discussed.

Animals↗
PubMed1978

Folate antagonists. 12. Antimalarial and antibacterial effects of 2,4-diamino-6-[(aralkyl and alicyclid)thio-, sulfinyl-, and sulfonyl]quinazolines.

A series of 2,4-diamino-6-[(aralkyl and alicyclic)thio-, sulfinyl-, and sulfonyl]quinazolines was prepared via condensation of 5-chloro-2-nitrobenzonitrile or 5,6-dichloro-2-nitrobenzonitrile with the appropriate aralkyl or alicyclic thiopseudourea, reduction of the resulting 2-nitro-5-[(aralkyl or alicyclic)thio]benzonitrile with stannous chloride to the amine, and cyclization with chloroformamidine hydrochloride. Oxidation was effected with hydrogen peroxide or the bromine complex of 1,4-diazabicyclo[2.2.2]octane. These analogues when examined for suppressive activity against drug-sensitive lines of Plasmodium berghei in mice were not as active as 2,4-diamino-6-[3,4-dichlorobenzyl)amino]quinazoline (Ia).

Animals↗
PubMed2004

Schedule-dependent synergism and antagonism between pemetrexed and paclitaxel in human carcinoma cell lines in vitro.

Pemetrexed is a novel multitargeted antifolate with significant clinical activity against a variety of tumors. We studied the schedule-dependent cytotoxic effects of pemetrexed in combination with paclitaxel in vitro to improve our understanding of how this combination might be used clinically. Human lung cancer A549 cells, breast cancer MCF7, ovarian cancer PA1, and colon cancer WiDr cells were exposed to both pemetrexed and paclitaxel in vitro. Cell growth inhibition after 5 days was determined and the effects of drug combinations were analyzed by the isobologram method (Steel and Peckham). Simultaneous exposure to pemetrexed and paclitaxel for 24 h produced antagonistic effects in A549 and PA1 cells, additive/antagonistic effects in MCF7 cells, and additive effects in WiDr cells. Pemetrexed for 24 h followed by paclitaxel for 24 h produced synergistic effects in A549 and MCF7 cells and additive effects in PA1 and WiDr cells, while the reverse sequence produced additive effects in all four cell lines. Cell cycle analysis supported these observations. Our findings suggest that the simultaneous administration of pemetrexed and paclitaxel is suboptimal. The optimal schedule of pemetrexed in combination with paclitaxel is the sequential administration of pemetrexed followed by paclitaxel, and this schedule should be assessed in clinical trials for the treatment of solid tumors.

Antineoplastic Combined Chemotherapy Protocols↗