Inhibition of human dihydrofolate reductase by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s. A quantitative structure-activity relationship analysis

The inhibitory activity of 101 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines against purified dihydrofolate reductase from human lymphoblastoid cell (WIL 2) has been studied. From the obtained Kiapp values, quantitative structure-activity relationships (QSAR) have been derived. The QSAR from human dihydrofolate reductase are compared with QSAR for triazines inhibiting bovine and murine tumor DHFR, as well with QSAR for their inhibitory action on murine tumor cell culture.     

Quantitative structure-activity relationship of antifolate inhibition of bacteria cell cultures resistant and sensitive to methotrexate

Sets of 5-(substituted benzyl)-2,4-diaminopyrimidines and 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3-substituted phenyl)-s-triazines as well as several other antifolates were tested as inhibitors of Escherichia coli dihydrofolate reductase and E. coli cell cultures both sensitive and resistant to methotrexate. From the results quantitative structure-activity relationships (QSAR) were formulated. The triazines were found to inhibit sensitive and resistant cell cultures to the same degree, but the benzylpyrimidines showed marked differences against the two types of cells. Increased hydrophobicity produced benzylpyrimidines more active against the resistant E. coli cell. Metroprine did not discriminate between the two types of cells cultures, but pyrimethamine and 2,4-diamino-6-(2,5-dimethoxybenzyl)-5-methylpyrido[2,3-d]pyrimidin e (BW 301U) did. The results are compared with triazines and benzylpyrimidines acting on Lactobacillus casei and murine tumor cells sensitive and resistant to methotrexate. QSAR is shown to be an effective means for detecting receptor differences.     

一种新的三嗪类抗锥虫药:SIPI-1029及其类似物的合成和抗原虫作用

合成了1,2-二氢-2,2-二甲基-4,6-二氨基-1-(ω-卤代烷氧基)-s-三嗪类和O,O’-双(4,6-二氨基-1,2-二氢-2,2-二取付-s-三嗪-1-基)烷烃二醇两类化合物,它们大多有较好的体内抗疟原虫(Plasmodium berghei)作用,化合物IIc～e对用伊氏锥虫(Trypanosoma evansi)感染的小鼠,有较好的作用,经深入的药理、毒理和药代动力学以及疗效等研究,化合物IIe(SIPI-1029,T-46)被证明是一高效、低毒并有较长的血药半衰期的抗锥虫新药。     

三嗪类化合物对小鼠成淋巴细胞瘤离体二氢叶酸还原酶活性和对瘤细胞生长抑制作用的定量相关关系

三嗪类化合物对瘤细胞生长的抑制作用,和对自瘤细胞分离的二氢叶酸还原酶活性的抑制作用的差异,经多重回归分析建立的模型表明,与化合物的克分子折射呈负性相关。瘤组织酶与正常酶活性的抑制作用呈平行关系。     

三嗪类化合物对L.casei离体二氢叶酸还原酶活性和L.casei细胞生长抑制作用的定量相关关系

三嗪类化合物抑制L.casei细胞生长作用和抑制离体的二氢叶酸还原酶活性,经多重回归分析建立的活性相关方程,表明在抑制拮抗株和敏感株生长作用时,较抑制离体酶需有更高的疏水性,与Hansch分析的推论是一致的。     

三嗪类化合物对小鼠成淋巴细胞瘤离体二氢叶酸还原酶活性和对瘤细胞生长抑制作用的定量相关关系

三嗪类化合物对瘤细胞生长的抑制作用,和对自瘤细胞分离的二氢叶酸还原酶活性的抑制作用的差异,经多重回归分析建立的模型表明,与化合物的克分子折射呈负性相关。瘤组织酶与正常酶活性的抑制作用呈平行关系。     

Crystallography, quantitative structure-activity relationships, and molecular graphics in a comparative analysis of the inhibition of dihydrofolate reductase from chicken liver and Lactobacillus casei by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazine s

The inhibition of dihydrofolate reductase from chicken liver and from Lactobacillus casei has been studied with 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines. It was found that for the chicken enzyme, inhibitor potency for 101 triazines was correlated by the following equation: log 1/Kiapp = 0.85 sigma tau' - 1.04 log (beta X 10 sigma tau' + 1) + 0.57 sigma + 6.36. The parameter tau' indicates that for certain substituents, tau = 0. In the case of the L. casei DHFR results, meta and para derivatives could not be included in the same equation. For 38 meta-substituted compounds, it was found that log 1/Kiapp = 0.38 tau'3-0.91 log (beta X 10 tau'3 + 1) + 0.71I + 4.60 and for 32 para-substituted phenyltriazines log 1/Kiapp = 0.44 tau'4-0.65 log (beta tau'4 + 1') - 0.90 upsilon + 0.69I + 4.67. In the L. casei equation, I is an indicator variable for substituents of the type CH2ZC6H4-Y and ZCH2C6H4-Y, where Z = O, NH, S, or Se. The parameter upsilon is Charton's steric parameter, which is similar to Taft's Es. The mathematical models obtained from correlation analysis are compared with stereo color graphics models.     

Synthesis and antifolate activity of new diaminopyrimidines and diaminopurines in enzymatic and cellular systems.

The following new 2,4-diamino-6-methylpyrimidines, 5-cyclohexylmethyl, 5-cyclohexylethyl,and 5-(2-naphthyl), as well as 2,6-diaminopurines, 8-adamantyl and8-adamantylmethyl, were synthesized as potential antifolates. Tese, as well as three known compounds, 2,4-diamino-5-cyclohexyl-6-methylpyrimidine, 2,4-diamino-5-(1-naphthyl) -6- methylpyrimidine, and 2,6-diaminopurine, were compared with respect to the inhibition of growth of mammalian cells in culture (TA 3) and with respect to the inhibition of partially purified dihydrofolate reductase. All of the pyrimidines except for the 5-(1maphthyl) derivative were competitive inhivitors of dihydrofolate reductase, with K values ranging from 0.07 to 0.04 pM. They were 2-5 times better as inhibitors of the isolated dihydrofolate reductase than of the cell growth. 2,4-Diamino-5-(1-naphthyl)-6-methylpyrimidine was a noncomptive inhivitor of the enzyme with a Kvalue of 56 pM. This compound was more potent in inhibiting cell growth than the isolated enzyme. indicating that its biological activity was not related to the inhibition of dihydrofolate reductse. All of the purine derivatives were poor growth inhibitors and although some of them inhibited isolated dihydrofolate reductase, their mode of action in cellular system did not seem to concern folate metabolism, as judged by the inability of hypoxanthine, and glycine to provide protection. The implication of these findings as to the structural requirements for inhibition of dihydrofolate reductase is discussed. The implication of these findings as to the structural requirements for inhibition of dihydrofolate reductase is discussed. The pitfalls of the determinition of ID-50 values instead of a complete kinetic analysis in structure-activity studies are emphasized.     

Quantitative structure-activity relationship of triazine-antifolate inhibition of Leishmania dihydrofolate reductase and cell growth

Quantitative structure-activity relationships have been formulated for the inhibition of Leishmania major dihydrofolate reductase (DHFR) and for inhibition of promastigote cell growth by a series of 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3-substituted-phenyl)-s-triazine s. The inhibition of DHFR is best correlated by a modified variable for hydrophobicity of the 3-X substituent (pi'3), an alkoxy group indicator variable (IOR), a disposable parameter (beta) obtained by iteration, and a variable that parameterizes steric effects (MR) in the equation, log 1/Ki = 0.65 pi'3 - 1.22 log (beta X 10 pi'3 + 1) - 1.12IOR + 0.58MRY + 5.05 (r = 0.965). The EC50 values for triazine inhibition of L. major cell growth in culture are correlated by the equation log 1/EC50 = 0.21 pi 3 + 0.44 log 1/Ki + 0.53 (r = 0.960). When compared to DHFR from human, other vertebrates, and E. coli, L. major DHFR differs in that it optimally binds triazine congeners that are much more hydrophobic. Furthermore, in contrast to other DHFR's studied, triazine binding to L. major DHFR does not seem to be influenced by the electronic characteristics of the 3-X substituent of the parent triazine molecule. However, L. major DHFR is more sensitive to the steric effects and polarizability of the 3-X substituent. Our results indicate that triazines inhibit L. major promastigote growth via direct inhibition of DHFR as is shown by the good correlation between log 1/Ki values for inhibition of the purified enzyme and log 1/EC50 values for inhibition of cell culture growth. Two lipophilic, sterically large analogues of this triazine series showed selectivity for L. major DHFR over human DHFR. Further optimization of the MR and IOR terms in the above QSAR equations may provide even more selective inhibitors.     

2,4-Diamino-5-benzylpyrimidines and analogues as antibacterial agents. 12. 1,2-Dihydroquinolylmethyl analogues with high activity and specificity for bacterial dihydrofolate reductase

Twelve 2,4-diamino-5-[(1,2-dihydro-6-quinolyl)methyl]pyrimidines containing gem-dimethyl or fluoromethyl substituents at the 2-position of the dihydroquinoline ring were prepared by condensations of dihydroquinolines with 2,4-diamino-5-(hydroxymethyl)pyrimidine. The dihydroquinolines were produced from the reaction of anilines with mesityl oxide or fluoroacetone. In some cases, 1-aryl-2,4-dimethylpyrroles were obtained as byproducts. Most of these pyrimidines were highly inhibitory to Escherichia coli dihydrofolate reductase (DHFR) and also had high specificity for the bacterial enzyme. 2,4-Diamino-5-[[1,2-dihydro-2,4-dimethyl-3-fluoro-2-(fluoromethyl)-8- methoxy-6(1H)quinolyl]methyl]pyrimidine had an apparent Ki value for E. coli DHFR 13 times lower than that of the control, trimethoprim (1), and was 1 order of magnitude more selective for the bacterial enzyme. It had outstanding activity against Gram-positive organisms in vitro, as well as broad-spectrum antibacterial activity equivalent to that of 1. The results of in vivo testing will be reported elsewhere. The gem-dimethyl substituents of the dihydroquinoline derivatives are considered to be responsible for the high selectivity, as well as contributing to potent bacterial DHFR inhibition. Molecular models are presented which suggest the probable interactions with the bacterial enzyme.     

Synthesis and biological activity of 8-oxadihydropteridines.

A series of 6-substituted and 6,7-disubstituted pyrimido[4,5-b][1,4]oxazines (8-oxadihydropteridines) was synthesized through the condensation of an alpha-halo ketone and 2,5-diamino-4,6-pyrimidinediol. The resulting 8-oxadihydropteridines were assayed as potential antifolates in a dihydrofolate reductase enzyme system. The 2-amino-4-hydroxyoxa-dihydropteridines were found to possess greater biological activity than the corresponding 2,4-diamino compounds. The pteroic acid homeostere 2-amino-4-hydroxy-6-phenethyl-8-oxadihydropteridine was the most potent of the compounds tested.     

Identification of new sulfur-containing metabolites of naphthalene in mouse urine

Seven acidic sulfur-containing metabolites were isolated from mouse urine following administration of naphthalene. The metabolites have been identified as (1-hydroxy-1,2-dihydro-2-naphthalenylthio)acetic acid (I), 2-hydroxy-3-(1-hydroxy-1,2-dihydro-2-naphthalenylthio)propanoic acid (II), (1,2,3-trihydroxy-1,2,3,4-tetrahydro-4-naphthalenylthio)acetic acid (III), and N-acetyl-S-(1-hydroxy-1,2-dihydro-2-naphthalenyl)-L-cysteine (IV). The dehydration products of I, II, and IV, namely 1-(naphthalenylthio)acetic acid (V), 2-hydroxy-3-(1-naphthalenylthio)propanoic acid (VI), and N-acetyl-S-(1-naphthalenyl)-L-cysteine (VII), respectively, were also present in several urinary extracts. Nine methylthio derivatives were identified in the neutral extract of urine. These metabolites were the following: 1-methylthionaphthalene, trans-1-hydroxy-2-methylthio-1,2-dihydronaphthalene, two stereoisomeric 1,2,3-trihydroxy-4-methylthio-1,2,3,4-tetrahydronaphthalenes, 1,3-di(methylthio)-2,4-dihydroxy-1,2,3,4-tetrahydronaphthalene, 1,4-di(methylthio)-2,3-dihydroxy-1,2,3,4-tetrahydronaphthalene, two methylthiohydroxy-naphthalenes, and a methylthiodihydroxydihydronaphthalene. Following intraperitoneal administration of N-acetyl-S-(1-hydroxy-1,2-dihydro-2-naphthalenyl)-L-cysteine to mice, the acidic metabolites I, II, and unchanged IV were found. The gas-chromatographic and gas chromatographic-mass spectral properties of the methyl ester-trimethylsilyl derivatives of the acidic sulfur metabolites of naphthalene are presented.     

On the optimization of hydrophobic and hydrophilic substituent interactions of 2,4-diamino-5-(substituted-benzyl)pyrimidines with dihydrofolate reductase

The inhibition constants (Kiapp) were obtained from the action of 68 2,4-diamino-5-(substituted-benzyl)pyrimidines on dihydrofolate reductase from an Escherichia coli strain MB 1428. Subsequently, these results were used to formulate appropriate quantitative structure-activity relationships (QSAR). Once again these equations emphasize the paramount importance of steric/dispersion factors in enhancing antibacterial potency. Hydrophobicity also plays a role, albeit a minor one. Comparisons with the QSAR obtained versus prokaryotic dihydrofolate reductase (DHFR) demonstrate subtle differences in binding behavior between meta and para substituents which may be effectively maximized in the design of more efficacious and selective antibacterial agents. The bacterial and avian QSAR equations can be used to calculate selectivity indices for trimethoprim, tetroxoprim, and two other specially designed 2,4-diamino-5-(substituted-benzyl)pyrimidines.     

Synthesis and evaluation of 2,4-diaminoquinazoline antifolates with activity against methotrexate-resistant human tumor cells

In an attempt to find potent antifolates with selectivity against tumor cells with intrinsic or acquired resistance to methotrexate, eleven nonclassical 2,4-diaminoquinazoline antifolates were synthesized and tested as inhibitors of dihydrofolate reductase from L5178Y cells. Several compounds appeared to be good enzyme inhibitors, with I50 values around 1 nM. Two of the compounds were also good inhibitors of cell growth in vitro. One of these (PKC-32, 9-(2,4-diamino-5-methylquinazoline-6-methylene)aminophenanthren e) appeared to be 100-fold more potent than methotrexate as an inhibitor of growth of a methotrexate-resistant cell line with impaired transport for methotrexate. PKC-32 and PKC-155 were also tested against mouse tumors in vivo. PKC-32 was modestly active in vivo as compared with methotrexate. This drug may be a useful agent in the treatment of methotrexate-resistant tumors.     

Synthesis of N-{4-[(2,4-diamino-5-methyl-4,7-dihydro-3H-pyrrolo[2,3-d]pyrimidin-6-yl)thio]benzoyl}-L-glutamic acid and N-{4-[(2-amino-4-oxo-5-methyl-4,7-dihydro-3H-pyrrolo[2,3-d]pyrimidin-6-yl)thio]benzoyl}-L-glutamic acid as dual inhibitors of dihydrofolate reductase and thymidylate synthase and as potential antitumor agents

Two novel classical antifolates N-{4-[(2,4-diamino-5-methyl-4,7-dihydro-3H-pyrrolo[2,3-d]pyrimidin-6-yl)thio]benzoyl}-L-glutamic acid 3 and N-{4-[(2-amino-4-oxo-5-methyl-4,7-dihydro-3H-pyrrolo[2,3-d]pyrimidin-6-yl)thio]benzoyl}-L-glutamic acid 4 were designed, synthesized, and evaluated as antitumor agents. Compounds 3 and 4 were obtained from 2,4-diamino-5-methylpyrrolo[2,3-d]pyrimidine 7 and 2-amino-4-oxo-5-methylpyrrolo[2,3-d]pyrimidine 12, respectively, in a concise three-step sequence. Compound 3 is the first example, to our knowledge, of a 2,4-diamino classical antifolate that has potent inhibitory activity against both human dihydrofolate reductase (DHFR) and human thymidylate synthase (TS). Compound 4 was a dual DHFR-TS inhibitor against the bifunctional enzyme derived from Toxoplasma gondii (tg). Further evaluation of the mechanism of action of 3 implicated DHFR as its primary intracellular target. Both 3 and 4 were folylpolyglutamate synthetase (FPGS) substrates. Compound 3 also inhibited the growth of several human tumor cell lines in culture with GI50 < 10(-8) M. This study shows that the pyrrolo[2,3-d]pyrimidine scaffold is conducive to dual DHFR-TS and tumor inhibitory activity, and the potency is determined by the 4-position substituent.     

Design and synthesis of 4,6-di-tert-butyl-2,3-dihydro-5-benzofuranols as a novel series of antiatherogenic antioxidants

Antioxidants have been considered as potential antiatherogenic agents by inhibiting oxidation of low-density lipoprotein (LDL), albeit vitamin E, a natural antioxidant, has failed to show reduction on atherosclerosis in clinical trials. We have rationally designed and synthesized a novel series of antioxidants, 4,6-di-tert-butyl-2,3-dihydro-5-benzofuranols, to overcome the clinical limitation of vitamin E. In vitro, the compounds showed a potent inhibitory effect on lipid peroxidation detected as 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (MCLA)-dependent chemiluminescence in linoleic acid autoxidation. They also inhibited the LDL oxidation induced by Cu(2+), and the inhibition is more potent than that of vitamin E and probucol. In vivo, 4,6-di-tert-butyl-2,3-dihydro-2,2-dipentyl-5-benzofuranol (BO-653, 1f), an optimal compound, showed the highest concentration in plasma and LDL fraction in Watanabe heritable hyperlipidemic rabbits, due to its high affinity to LDL. The isolated LDL samples from the 1f-treated rabbits showed potent resistibility to LDL oxidation. Compound 1f has been taken into clinical trials.     

Design, synthesis, and biological evaluation of 2,4-diamino-5-methyl-6-substituted-pyrrolo[2,3-d]pyrimidines as dihydrofolate reductase inhibitors.

2,4-diamino-5-methyl-6-(substituted-phenyl)thiopyrrolo[2,3-d]pyrimidines 4-11 were synthesized as dihydrofolate reductase (DHFR) inhibitors against opportunistic pathogens that afflict patients with AIDS. Synthesis was achieved from 2,4-diamino-5-methypyrrolo[2,3-d]pyrimidine and substituted phenylthiols under modified conditions reported by Gangjee et al. Some of these compounds were potent and selective against DHFR from both Toxoplasma gondii and Mycobacterium avium compared to mammalian DHFR. Compound 11 with a 1-naphthyl substituent is 16-fold more potent and equally selective against Toxoplasma gondii DHFR as the clinically used trimethoprim.     

Synthesis and pharmacological evaluation of some phenothiazines as antidepressants.

10-Hydrazino acetyl phenothiazine (II) has been converted to N-10-acetyl amino phenothiazine-N-phenyl thiourea (III) which have been converted to 3-aryl-1-(10-phenothiazine acetyl amino)-2,3-dihydro-2-thioxo-4,6-(1H,5H) pyrimidinones (IV) on condensation with aryl amines and aryl aldehydes yielded 3-aryl-1-(10-Phenothiazine acetyl amino)-5-(substituted phenyl amino methyl)-2,3-dihydro-2-thioxo-4,6-(1H, 5H) pyrimidinediones (Va-k) and 3-aryl-1-(10-phenothiazine acetyl amino)-5-(substituted phenylidine)-2,3-dihydro-2-thioxo-4,6-(1H, 5H) pyrimidinediones (vl-o). The compounds were screened for their antidepressant activity against a tricyclic antidepressant (imipramine). Compounds Va, Vf, Vm and Vi exhibited activity better than imipramine with no toxicity (ALD50 greater than 1000 mg/kg) but Vi showed some side effects.     

Pharmacokinetic behaviour of cisplatin in peritoneal fluid after intraperitoneal administration of cisplatin-loaded microspheres.

The objective of this study was to establish a pharmacokinetic model for the estimation of unchanged cis-dichlorodiammine-platinum (II) (CDDP) concentration in peritoneal fluid after intraperitoneal administration of cisplatin-loaded microspheres (CDDP-MS) and to elucidate the accuracy of this model by comparisons between actual and simulated values after intraperitoneal administration of CDDP-MS. We developed a method enabling the precise and quick assessment of the drug concentration in the peritoneal cavity. The pharmacokinetic parameters obtained after intravenous bolus injection at a dose of 2 mg kg(-1) were total body clearance (1026 mL h(-1) kg(-1)), elimination rate constant (3.24 h(-1)) and distribution volume of systemic circulation (316.7 mL kg(-1)). After an intraperitoneal bolus injection at a dose of 5 mg kg(-1), the absorption rate constant from the peritoneal cavity (3.64 h(-1)) and the distribution volume of the peritoneal cavity (13.5 mL kg(-1)) were determined. The protein-binding rate constant in ascites was 0.58 h(-1). Using these pharmacokinetic parameters, we established a pharmacokinetic model consisting of two compartments. Administration of CDDP-MS at a dose of 10 mg kg(-1), which released CDDP over 7 days in-vitro, yielded sustained concentrations of unchanged CDDP (1-2 mg mL(-1)) in the peritoneal cavity that persisted for 7 days, and that were predictable by applying the in-vitro dissolution profile to the pharmacokinetic model. The findings obtained from this study are useful for understanding the basic pharmacokinetic characteristics of unchanged CDDP in the peritoneal cavity and may also be important in the development of optimized CDDP-MS formulations.     

Umsetzungen des 1,2-Dihydro-2-methyl-papaverinols in verdünnter Essigsäure

Reactions of 1,2-Dihydro-2-methyl-papaverinol in dilute Acetic Acid When 1,2-dihydro-2-methyl-papaverinol (II) is treated with 2% acetic acid, 3,4-dihydro-6,7-dimethoxy-3-(3,4-dimethoxy-α-hydroxy-benzyl)-2-methyl-isoquinolinium-ion (IX), 9-hydroxylaudanosin (I), 6,7-dimethoxy-2-methyl-isoquinolinium-ion (III b) and veratraldehyd (IV) are formed.