Synthesis and Antioxidant Activity of 7-Thio Derivatives of 6,7-Dihydro-1H-cyclopenta[d]pyrimidine-2,4(3H,5H)-dione

New 7-thio derivatives of 6,7-dihydro-1H-cyclopenta[d]pyrimidine-2,4(3H,5H)-dione have been synthesized by the reaction of 3-cyclohexyl-7-thio-6,7-dihydro-1H-cyclopenta[d]pyrimidine-2,4(3H,5H)-dione with alkylhalogenides. The synthesized compounds were tested for antioxidant activity on the model of Fe²⁺-dependent oxidation of adrenaline in vitro. It was found that the antiradical activity of 7-thio derivatives of 6,7-dihydro-1H-cyclopenta[d]pyrimidine-2,4(3H,5H)-dione significantly depends on the structure of the substituent which is part of the thioether fragment of the base molecule.     

Synthesis and pharmacological evaluation of newer thiazolo [3,2-a] pyrimidines for anti-inflammatory and antinociceptive activity

A new series of thiazolo [3,2-a] pyrimidine derivatives was designed and synthesized using 4-fluoroaniline and ethylacetoacetate as starting material. Anti-inflammatory activity was assessed by the rat paw edema method and antinociceptive activity was evaluated by thermal stimulus technique. The compounds 5-(4-chlorophenyl)-2-(4-fluorobenzylidene)-7-methyl-3-oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid (4-fluorophenyl)amide (3l) and 2-(4-chlorobenzylidene)-5-(4-fluorophenyl)-7-methyl-3-oxo-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid (4-fluorophenyl)amide (3q) were found to possess significant anti-inflammatory and antinociceptive activities. These compounds also showed lower ulcerogenic activity and higher ALD₅₀ values. Compounds with an aryl ring substituted with a smaller electron withdrawing group at the fourth position displayed better activity than the other derivatives.     

Mehrcyclische Azine mit Heteroatomen in 1- und 3-Stellung, 40. Mitt. Synthese heterocyclischer Immunmodulatoren, 2. Mitt.: 3-Mercaptoalkylthieno[2,3-d]pyrimidin-2,4(1H,3H)-dione: Synthese und Prüfung auf immunstimulatorische Wirksamkeit

Polycyclic Azines, XL: Synthesis of Heterocyclic Immunomodulators, II: 3-Mercaptoalkylthieno[2,3-d]pyrimidine-2,4(1H,3H)-diones: Synthesis and Test for Immuno-stimulating Activity A series of 3-mercaptoalkylthieno[2,3-d]pyrimidine-2,4(1H,3H)-diones 3 was prepared and their immuno-stimulating activity was examined. The title compounds were obtained conveniently by hydrolytic ring cleavage of fused thiazolo- or 1,3-thiazino-thicnopyrimidines 1 under alkaline or acidic reaction conditions. The ms fragmentation of the thieno[2,3-d]pyrimidine-2,4-diones 3 is discussed. In the delayed type hypersensitivity (DTH) test some compounds 3 showed immuno-stimulating activities in the range of isoprinosine.     

Enhancement of hepatocarcinogenesis by combined administration of food-derived heterocyclic amines at low doses in the rat

Effects of simultaneous administration of five or 10 heterocyclic amines (HCAs) at low dose levels on rat liver carcinogenesis were investigated using a medium-term bioassay protocol. Male F344 rats were initially given diethylnitrosamine (DEN, 200 mg/kg, ip) and received HCAs starting 2 wk later for 6 wk. All animals were subjected to two-thirds partial hepatectomy at wk 3 and were killed at wk 8. Five carcinogenic HCAs in the first two experiments: 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole, 2-aminodipyrido[1,2-a:3′,2′-d]imidazole, 2-amino-3-methylimidazo-[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo-[4,5-f]quinoxaline in experiment 1 and 3-amino-1-methyl-5H-pyrido[4,3-b]indole, 2-amino-6-methyl-dipyrido[1,2-a:3′,2′-d]imidazole,2-amino-3-methyl-9H-pyrido-[2,3-b]indole, 2-amino-9H-pyrido[2,3-b]indole, and 2-amino-l-methyl-6-phenylimidazo[4,5-b]pyridine in experiment 2] were administered together or individually in the diet at levels of 1/1, 1/5 or 1/25 carcinogenic doses, and all 10 chemicals were given at 1/10 or 1/100 levels in experiment 3. Induction of preneoplastic glutathione S-transferase placental form (GST-P) positive foci was increased in some combination groups over the sums of effects for the individual groups at the same doses (apparent synergism). This was most obvious in the group given all 10 chemicals at the 1/10 dose levels. However, it was of interest that the values in the combined groups were generally very close to the averages of five or 10 individual results for the corresponding higher dose groups, indicating isoadditivity of HCA effects. True (strict) synergism, however, was expected for the results of groups including Ph1P and Trp-P-2 in combination, since they are non-hepatocarcinogenic but induce the key metabolic enzyme for HCAs (CYPIA2).     

Synthesis and evaluation of in vitro antitubercular activity and antimicrobial activity of some novel 4H-chromeno[2,3-d]pyrimidine via 2-amino-4-phenyl-4H-chromene-3-carbonitriles

Novel 5-phenyl-1,5-dihydro-2H-chromeno[2,3-d]pyrimidine-2,4(3H)-dithiones, 5-phenyl-3,5-dihydro-4H-chromeno[2,3-d]pyrimidin-4-ones, 7-phenyl-7,9-dihydro-8H pyrimido[5′,4′:5,6]pyrano[3,2-h]quinolin-8-ones, and 4-amino-5-phenyl-1,5-dihydro-2H-chromeno[2,3-d]pyrimidine-2-thiones were synthesized form 2-amino-4-phenyl-4H-chromene-3-carbonitrile. The newly synthesized compounds were characterized by IR, ¹H-NMR, ¹³C-NMR, Mass spectra, and Elemental analysis. The compounds were evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis H ₃₇ Rv and antibacterial activity against Staphylococcus Aureus [ATCC-25923] and Streptococcus pyogenes [MTCC-443] as Gram-positive, Escherichia coli [ATCC-25922], and Pseudomonas aeruginosa [MTCC-441] as Gram-negative bacterial strains and antifungal activity against Aspergillus niger [MTCC-282]. Some of these derivatives exhibited pronounced antitubercular and antimicrobial activities.     

A Structured–Activity Relationship Study of Batracylin Analogues

A number of isoindolo[l ,2-b]quinazolines and some benzo[4,5]isoquinolino[l,2-b]quinazolines as structural modification analogues of the antitumor compound batracylin were synthesized and evaluated against HL-60 cell growth and in topoisomerase II-mediated DNA cleavage assays. Of the compounds studied, 10,12-dihydro-7,8-methy lenedioxyisoindolo[ 1,2-b] quinazolin-12(10H)-one (1d), 2-amino-10,12-dihydroisoindolo[l ,2-b]quinazolin- 12(10H)-one (1p), and 2-amino-7,8-methylenedioxy-10,12-dihydroisoindolo[l ,2-b]quinazolin-12(10H)-one (1ab) exhibited good inhibitory activities against HL-60 cell lines as well as induction of topo II-mediated DNA cleavage activities.     

Synthesis,Anti-Inflammatory,and Ulcerogenicity Studies of Novel Substituted and Fused Pyrazolo[3,4-d]pyrimidin-4-ones

In the present investigation, some new pyrazolo[3,4-d]pyrimidin-4(5H)-one derivatives (7–12) as well as fused pyrazolo[3′,4′:4,5]pyrimido[1,2-b]pyridazin-4(1H)-one (14–16) and 7,8,9,10-tetrahydropyrazolo[3′,4′:4,5]pyrimido[1,2-b]-cinnolin-4(1H)-one (17) ring systems were synthesized using the starting compound 5-amino-6-methyl-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one (5). The structures of the newly synthesized compounds were elucidated by IR, ¹H NMR, ¹³C NMR, mass spectroscopy, and elemental analysis. The theoretical calculation of their lipophilicity as C log P was performed. The anti-inflammatory activity of all newly synthesized compounds was evaluated using the carrageenan-induced paw edema test in rats using indomethacin as the reference drug. Ulcer indices for the most active compounds were calculated. Seven compounds (10b, 11a–f) showed consistently good anti-inflammatory activity. In particular, 5-{[4-(4-bromophenyl)-3-(4-chlorophenyl)-1,3-thiazol-2(3H)-ylidene]amino}-6-methyl-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one (11e) and its 3,4-bis(4-chlorophenyl) analog (11f) were found to be the most effective among the other derivatives, showing activity comparable to that of indomethacin with minimal ulcerogenic effects. Correlation of the biological data of the active compounds with their theoretically calculated C log P values revealed that lipophilicity influences the biological response.     

Synthesis and <Emphasis Type="Italic">In Vitro</Emphasis> antiproliferative activity of 2-methyl-3-(2-piperazin-1-yl-ethyl)-pyrido[1,2-a]pyrimidin-4-one derivatives against human cancer cell lines

A series of new 2-methyl-3-(2-piperazin-1-yl-ethyl)-pyrido[1,2-a]pyrimidin-4-one derivatives 6a-j were synthesized by a nucleophilic substitution reaction of 2-methyl-3-(2-piperazin-1-ylethyl)-pyrido[1,2-a]pyrimidin-4-one with various sulfonyl chlorides. The compounds were characterized by different spectral studies. All the compounds were evaluated for their antiproliferative effect using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay method against four human cancer cell lines (K562, Colo-205, MDA-MB 231, IMR-32) for the time period of 24 h. Among the series, compounds 6d, 6e and 6i showed good activity on all cell lines except K562, whereas the other compounds in the series exhibited moderate activity. Compound 6d could be a potential anticancer agent and therefore deserves further research.     

Synthesis and psychotropic activity of 5-cyclohexyl-5-methyl-2-sulfanyl-3,4,5,6-tetrahydrobenzo[<Emphasis Type="Italic">h</Emphasis>]quinazolin-4-one

Ethyl 2-cyano-3-cyclohexyl-3-methyl-4-phenylbutanoate was synthesized from ethyl (2Z)-2-cyano-3cyclohexylbut-2-enoate using a Grignard reagent. It was shown that the reaction occurred exclusively at the ethylene bond. Because this cyanoester contained two asymmetric centers, PMR spectra showed two diastereoisomeric forms. These were cyclized in the presence of conc. H₂SO₄ into ethyl 4-amino-2-cyclohexyl-2-methyl-1,2-dihydronaphthalenecarboxylate, which was used to synthesize benzo[h]quinazolines, alkyl-substituted benzo[h]quinazolines, triazole, and tetrazole.     

Synthesis of new series of pyrazolo[4,3-d]pyrimidin-7-ones and pyrido[2,3-d]pyrimidin-4-ones for their bacterial and cyclin-dependent kinases (CDKs) inhibitory activities

Two series of pyrazolo[4,3-d]pyrimidin-7-ones and pyrido[2,3-d]pyrimidin-4-ones were designed, synthesised, and evaluated for their antibacterial activities and CDKs inhibitory activities. The pyridazine derivative: 6-phenyl-5-phenylhydrazono-2,3,4,5-tetrahydropyridazine-3,4-dione (3a) revealed activity against Staphylococcus aureus as Gram-positive bacteria while compound 2-(2-Ethoxyphenyl-5-Phenylpiperazinosulfonamido)-3H-pyrido[2,3-d]pyrimidin-4-one (13c) was showing moderate antifungal activity against Candida albicans.     

Synthesis and antibacterial evaluation of 6-azapyrimidines with α-methylene-γ-(4-substituted phenyl)-γ-butyrolactone pharmacophores

Abstract  

A series of 6-substituted 2-[(4-methylene-5-oxo-2-(4-substituted phenyl) tetrahydrofuran-2-yl)methyl]-1,2,4-triazine-3,5(2H,4H)-diones (5, 6) and 2,4-bis[(4-methylene-5-oxo-2-(4-substituted phenyl) tetrahydrofuran-2-yl)methyl]-1,2,4-triazine-3,5(2H,4H)-diones (9, 10) were designed, synthesized, and evaluated for antibacterial activity against Gram-positive and Gram-negative microorganisms. The synthesis of these compounds involved the Reformatsky-type reaction between ethyl α-(bromomethyl)acrylate and the proper ketones. Among these compounds, 2-[(4-methylene-5-oxo-2-phenyl tetrahydrofuran-2-yl)methyl]-1,2,4-triazine-3,5(2H,4H)-dione (5a) is the most active compound and shown the selective inhibition activity against Proteus vulgaris.     

Glutathione transferase-mediated and non-enzymatic activation and detoxication of the N-hydroxy derivative of Trp-P-2, a potent pyrolysate promutagen

1. Glutathione (GSH) transferase-mediated and non-enzymatic activation and detoxication of 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole (N-OH-Trp-P-2) were studied in vitro. N-OH-Trp-P-2 is an active metabolite of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), a mutagenic and carcinogenic heterocyclic amine.

2. The enzymatic GSH conjugation with N-OH-Trp-P-2 was catalysed by rat-liver GSH transferase and a rat-liver cytosol fraction to form three conjugates (CH-1, CH-2 and CH-3).

3. The mutagenicities of the GSH conjugates were studied by using Salmonella typhimurium TA98 as the tester strain.

4. The GSH conjugates except for CH-3 were completely detoxicated products, but CH-3 was found to be a more potent mutagen than N-OH-Trp-P-2.

5. The mutagenicity of CH-3 seemed to be due to the direct action of the conjugate, but not to N-OH-Trp-P-2 formed from it.     

A novel kainate receptor ligand [H]-(2S,4R)-4-methylglutamate: Pharmacological characterization in rabbit brain membranes

Since kainate evokes large non-desensitizing currents at α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, kainate is of limited use in discriminating between AMPA and kainate receptors. Following recent reports that (2S,4R)-4-methylglutamate is a kainate receptor-selective agonist, we have radiolabelled and subsequently characterized the binding of [³H]-(2S,4R)-4-methylglutamate to rabbit whole-brain membranes. [³H]-(2S,4R)-4-methylglutamate binding was rapid, reversible and labelled two sites (KD1 = 3.67 ± 0.50 nM/B_max1 = 0.54 ± 0.03 pmol/mg protein and K_D2 = 281.66 ± 12.33 nM/ B_max2 = 1.77 ± 0.09 pmol/mg protein). [³H]-(2S,4R)-4-methylglutamate binding was displaced by several non-NMDA receptor ligands: domoate > kainate -quisqualate -glutamate > 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX) (S)-AMPA = (S)-5-fluorowillardiine > NMDA. Neither the metabotropic glutamate receptor agonists (1S,3R)-ACPD or -AP4, together with the -glutamate uptake inhibitor -trans-2,4-PDC, influenced binding when tested at 100 μM. We conclude that [³H]-(2S,4R)-4-methylglutamate is a useful radioligand for labelling kainate receptors. It possesses high selectivity, and possesses a pharmacology similar to that for rat cloned low-affinity (Glu5 and 6) kainate receptor subunits.     

Synthesis,characterization, and antimicrobial activity of some new coumarin derivatives

A number of new [(4-methyl-2-oxo-2H-chromen-7-yl)amino]methylcoumarins (5a–c), benzofuran (6), and benzoxazol (7) were synthesized through the reaction of 7-amino-4-methylcoumarin (1) with a number of organic halides. In addition, series of N-substituted 2-[(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetohydrazide (11a–h) and (12a–d) were prepared from the reaction of 2-[(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetohydrazide (8) with corresponding heteroaryl/alkyl halides (2–4, 9, and 10). The synthesized compounds were characterized by elemental analysis and by spectroscopic techniques such as ¹H-NMR, ¹³C-NMR, and mass spectrometry and were tested for their in vitro antimicrobial activity. The newly synthesized compounds exerted significant inhibitory activity against the growth of tested bacterial strains and a few of them are found to be potent antimicrobial agents.     

Structure of a novel sulphur-containing metabolite of Acluracil (1-allyl-3,5-diethyl-6-chlorouracil)

1. A new sulphur-containing metabolite of 1-allyl-3,5-diethyl-6-chlorouracil, identified as 6,8-diethyl-2-hydroxymethyltetrahydrothiazolo[3,2-c]pyrimidine-5,7 (4H,6H)-dione, has been demonstrated in rabbit urine.

2. The mechanism of the formation of this metabolite is discussed and a metabolic pathway for the formation of methylthio metabolites is proposed.     

Identification of important structural features of thiazolo[4,5-d]pyrimidines required for potent antifungal activity

Pyrimidines, either mononuclear or condensed with other heterocycles have established its importance in medicinal chemistry. Variety of biological activities have been reported by thiazolo[4,5-d]pyrimidine derivatives. The present work describes the synthesis and antifungal activity of several 3-(substituted)-5-(substituted)phenylamino-6-(substituted)phenylthiazolo[4,5-d]pyrimidine-7(6H)-one-2(3H)-thiones. The target compounds were synthesized by cyclocondensation of 4-amino-5-carbethoxy-3-(substituted)thiazolo-2(3H)-thione and S-methyl di(substituted)phenylisothiourea. All synthesized compounds were tested for minimum inhibitory concentration against different fungal strains such as, Aspergillus niger, A. clavatus and Candida albicans and compared with fluconazole and nystatin as reference drug. Some of the compounds have exhibited potent inhibitory activity on all fungal strains, and were found more potent than reference standard. Some of the important structural features required for broad spectrum activity in this series have been derived.     

Synthesis and antimicrobial activity of n,7-diaryl-5-methyl-4,7-dihydrotetrazolo[1,5-<Emphasis Type="Italic">a</Emphasis>] pyrimidine-6-arboxamides

N,7-Diaryl-5-methyl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxamides were synthesized by three-component reaction of acetoacetanilides (2-methylacetoacetanilide, 2,4-dimethylacetoacetanilide, 4-chloroacetoacetanilide, o-acetoacetanilide) with a mixture of aromatic aldehyde and 5-aminotetrazole. The proposed structures are confirmed by IR and PMR spectroscopy and mass spectrometry. The synthesized compounds are characterized with respect to antimicrobial activity.     

Formation of mutagens in boiled pork extract

When boiled pork extract was heated under reflux at 102 °C for 4 hr mutagens, which were detected using Salmonella typhimurium strains TA98 and TA1538, were formed. The level of mutagenicity was dependent on the concentration of pork in the extract, the duration of boiling and on pH; the optimum pH for mutagen formation was found to be 9 to 11. Thin-layer chromatographic analysis showed that the mutagens formed in boiled pork extract were chromatographically distinguishable from benzo[a]pyrene and from the primary mutagenic pyrolysis products of tryptophan (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and of glutamic acid (2-amino-6-methyldipyrido[1,2−a:3′,2′-d]imidazole)     

Heterocyclen via Mannichbasen, 7. Mitt. Synthese von Pyrazolo[1,5-a]pyrido[2,3-d]pyrimidin-9(4H)-onen

Heterocycles via Mannich Bases, VII: Synthesis of Pyrazolo[1,5-a]pyrido[2,3-d]pyrimidin-9(4H)-ones The title compounds 4 are synthesised from 5-amino-3-methylpyrazolo[1,5-a]pyrimidin-7(4H)-one (2) and ketone Mannich bases or dehydro Mannich bases.     

Synthesis of new hexahydro- and octahydropyrido[1,2-c]pyrimidine derivatives with an arylpiperazine moiety as ligands for 5-HT1A and 5-HT2A receptors

Synthesis applied to prepare compounds 5–15 and 17–22 discussed in this paper has been presented in Scheme 1. Multi-stage preparation techniques were used to obtain 4-aryl-hexahydro 1–4 and (R,R) and (S,S) 4-aryl-octahydropyrido[1,2-c]pyrimidine-1,3-dione (16) derivatives, being the starting compounds for further modification. N-Alkylation of the imide group in compounds 1–4 and 16 followed, using 1,4-dibromobutane to yield monobromobutyl derivatives 5–8 and 17. Subsequent condensation of those compounds with appropriate 1-aryl or 1-heteroarylpiperazine led to the final hexahydro- 9–15 and octahydro- 18–22 pyrido[1,2-c]pyrimidine-1,3-dione derivatives. The final products were subjected to screening test to elucidate the affinity to 5-HT_1A and 5-HT_2A receptors.