Reactions of a series of 1-aminobenzimidazoles and 1-amino-3-methylbenzimidazolium chlorides with 2,4-pentanedione

Reactions of a series of 1-aminobenzimidazoles and 1-amino-3-methylbenzimidazolium chlorides with 2,4-pentanedione were carried out and pyridazino[1,6-a]benzimidazoles and 2-pyrazolylanilines were generated. The product ratios of these compounds remarkably depended on the reaction conditions and on the electronic character of the substituent at the benzene moiety. The possible mechanisms involved in these reactions are discussed.     

Metabolism of platelet activating factor (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) and 1-alkyl-2-acetyl-sn-glycerol by human endothelial cells

The metabolism of platelet activating factor (1-[1,2-3H]alkyl-2-acetyl-sn-glycero-3-phosphocholine) and 1-[1,2-3H]alkyl-2-acetyl-sn-glycerol was studied in cultures of human umbilical vein endothelial cells. Human endothelial cells deacetylated 1-[1,2-3H]alkyl-2-acetyl-sn-glycero-3-phosphocholine to the corresponding lyso compound (1-[1,2-3H]alkyl-2-lyso-sn-glycerol-3-phosphocholine) and a portion was converted to 1-[1,2-3H]alkyl-2-acyl(long-chain)-sn-glycero-3-phosphocholine. Lyso platelet activating factor (lyso-PAF) (1-[1,2-3H]alkyl-2-lyso-sn-glycero-3-phosphocholine) was detected in the media very early during the incubation and the amount remained higher than the level of the lyso product observed in the cells. Cellular levels of 1-[1,2-3H]alkyl-2-lyso-sn-glycero-3-phosphocholine were significantly higher than the acylated product (1-[1,2-3H]alkyl-2-acyl(long-chain)-sn-glycero-3-phosphocholine) at all times during the 60-min incubation period, which suggests that the ratio of acetylhydrolase to acyltransferase activities is greater in endothelial cells than in most other cells. When endothelial cells were incubated with 1-[1,2-3H]alkyl-2-acetyl-sn-glycerol, a known precursor of PAF, 1-[1,2-3H]alkyl-sn-glycerol was the major metabolite formed (greater than 95% of the 3H-labeled metabolites during 20- and 40-min incubations). At least a portion of the acetate was removed from 1-[1,2-3H]alkyl-2-acetyl-sn-glycerol by a hydrolytic factor released from the endothelial cells into the medium during the incubations. Only negligible amounts of the total cellular radioactivity (0.2%) was incorporated into platelet activating factor (1-[1,2-3H]alkyl-2-acetyl-sn-glycero-3-phosphocholine); therefore, it is unlikely that the previously observed hypotensive activity of 1-alkyl-2-acetyl-sn-glycerols can be explained on the basis of the conversion to platelet activating factor (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) by endothelial cells. Results of this investigation indicate that endothelial cells play an important role in PAF catabolism. Undoubtedly, the endothelium is important in the regulation of PAF levels in the vascular system.     

Vertebrate class distribution of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine acetylhydrolase in serum

Serum from numerous mammals and lower vertebrates contains an enzyme activity that is specific for the hydrolysis of the acetate moiety of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF, platelet activating factor). Acetylhydrolase (EC 3.1.1.47, 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine acetylhydrolase) was found in all mammalian sera with activity ranging from 11 (fetal calf) to 178 (rabbit) pmol acetate liberated/microliter serum/min. The enzyme is not present in avian serum but is a constituent of reptiles and bony fishes.     

Molluscicidal activity of 2-hydroxy-3-alkyl-1,4-naphthoquinones and derivatives

In the search for new molluscicidal agents we tested the activity of lapachol and other 2-hydroxy-3-alkylnaphthoquinones possessing nitrogenated alkyl chains, against the snail Biomphalaria glabrata. Lapachol, isolapachol and nor-lapachol showed strong molluscicidal activity against the adult snail (LD(90)<10 ppm) and significant toxicity against snail egg masses (LD(90)<0.2 ppm). As lapachol is easily extracted, and the derivatives can be synthesised without any difficulty, large-scale synthesis and field tests can be conducted, with a view to large-scale molluscicidal programs.     

Differential hydrolysis of 1-alkyl-2-acyl and diacylglycerophosphocholines by human and non-human phospholipases A2.

The activity of two human phospholipases A2, purified from synovial fluid and lumbar disc herniations, was tested using alkylacyl- and diacylglycerophosphocholines and the influence of the chemical link at the sn-1 position of glycerol was investigated. Both enzymes exhibited 2.5-3-fold selectivity for 1-ester-linked compared to 1-ether-linked phosphatidylcholine. No significant selectivity was observed with pancreatic phospholipase A2 while Naja naja naja venom enzyme was more efficient against 1-ether-phospholipids.     

Discovery of 3-alkyl-5-aryl-1-pyrimidyl-1H-pyrazole derivatives as a novel selective inhibitor scaffold of JNK3

Abstract

3-alkyl-5-aryl-1-pyrimidyl-1H-pyrazole derivatives were designed and synthesised as selective inhibitors of JNK3, a target for the treatment of neurodegenerative diseases. Following previous studies, we have designed JNK3 inhibitors to reduce the molecular weight and successfully identified a lead compound that exhibits equipotent activity towards JNK3. Kinase profiling results also showed high selectivity for JNK3 among 38 kinases. Among the derivatives, the IC₅₀ value of 8a, (R)-2-(1-(2-((1-(cyclopropanecarbonyl)pyrrolidin-3-yl)amino)pyrimidin-4-yl)-5-(3,4-dichlorophenyl)-1H-pyrazol-3-yl)acetonitrile exhibited 227?nM, showing the highest inhibitory activity against JNK3.     

Synthesis of 1,2,4-triazole C-nucleosides from hydrazonyl chlorides and nitriles

A series of 1,3-diaryl-5-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)-1H-1,2,4-triazole nucleosides (3a-f) were synthesized via the intermolecular cyclization of hydrazonyl chlorides with peracylated ribofuranosyl cyanide catalyzed by Yb(OTf)3 or AgNO3, respectively. Similarly, the 1,2,4-triazole of glucopyranosyl C-nucleosides 5a,b were prepared from the hydrazonyl chlorides and the nitrile 4. Alternatively, the 1,2,4-triazole N-nucleoside 8 was obtained from cyclization of the unsymmetrical bis[alpha-(4-methoxyphenyl)aminobenzylidene]-hydrazine with peracylated 1-amino-D-manno-pentitol.     

Synthesis of naphtho[2,3-a]phenoxazinium chlorides: structure-activity relationships of these heterocycles and benzo[a]phenoxazinium chlorides as new antimicrobials

Synthesised functionalised naphtho[2,3-a]phenoxazinium chlorides revealed great fluorescence with maximum emission wavelengths between 630 and 676 nm, in ethanol and water at physiological pH. Naphtho[2,3-a]phenoxazines, as well as a series of benzo[a]phenoxazines, were evaluated against Saccharomyces cerevisiae, in a broth microdilution assay. This family of compounds exhibited antifungal activity depending both on the substituents of the heterocycle nucleus as well as on its size. The best activities were obtained for four-ring systems, and particularly for 5,9-diaminobenzo[a]phenoxazines with R=Me, R(1)=H and R(2)=Et. As for R(3) substitution, the greatest efficiency was obtained for R(3)=(CH(2))(3)Cl, with a MIC of 3.75 microM. The linkage of different amino acids to the functional group of the 5-amino position of diaminobenzo[a]phenoxazinium moiety resulted in compounds with diverse antimicrobial efficiencies, depending on the polar character of the amino acid, on its linkage position and on the size of the alkyl chain linker.     

Biosynthesis of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet-activating factor) from 1-alkyl-2-acyl-sn-glycero-3-phosphocholine by rat alveolar macrophages. Phospholipase A2 and acetyltransferase activities during phagocytosis and ionophore stimulation

1-Alkyl-2-acyl-sn-glycero-3-phosphocholine (alkyl-acyl-GPC) comprises 11% of the total phospholipids of rat alveolar macrophages. This endogenous pool of alkylacyl-GPC was prelabeled by incubating the macrophages with [1,2-3H]alkyllyso-GPC (54 Ci/mmol), which enters the cells and is acylated. The effect of various stimuli on the synthesis and release into the media of labeled alkylacetyl-GPC (platelet-activating factor) from the cells was used to establish the role of inactive alkylacyl-GPC as a precursor of the biologically active derivative. A phagocytic agent (zymosan, 100 micrograms/ml) and an ionophore (A23187, 2 microM) stimulated the release of both alkylacetyl-GPC and alkyllyso-GPC into the media at the expense of cellular alkylacyl-GPC. Phospholipase A2 activity (at pH 4.5 and in 1 mM EDTA) was also increased in the media. The stimulatory effect of zymosan and the ionophore on alkylacetyl-GPC release was prevented by mepacrine (0.1 mM), an agent that inhibits the release of fatty acids from phospholipids. These data indicate that phospholipase activity is required for the biosynthesis of alkylacetyl-GPC. However, since the inhibitory effect of mepacrine was not apparent when acetate was present, it appears that the acetylation step is rate limiting. Exposure of alveolar macrophages in culture to zymosan or A23187 stimulated acetyltransferase activity 250-300%. In contrast, phorbol myristate acetate (1.6 microM), which stimulated the accumulation of lysophospholipids but not the level of alkylacetyl-GPC in the media, did not substantially increase acetyltransferase activity. We conclude that alkylacyl-GPC serves as a precursor of alkylacetyl-GPC and that the production of this potent mediator by rat alveolar macrophages can be stimulated by agents that affect phospholipase A2 and acetyltransferase activities. The latter enzyme appears to have a regulatory function in the biosynthesis of alkylacetyl-GPC.     

Formation of 1-alkyl-2-acetyl-sn-glycerols via the de novo biosynthetic pathway for platelet-activating factor. Characterization of 1-alkyl-2-acetyl-sn-glycero-3-phosphate phosphohydrolase in rat spleens

1-Alkyl-2-acetyl-sn-glycerol (alkylacetyl-G) is an important intermediate in the biosynthesis of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet-activating factor) from 1-alkyl-2-lyso-sn-glycero-3-phosphate (alkyllyso-GP) via the de novo pathway. In the present investigation, we have characterized a 1-alkyl-2-acetyl-sn-glycero-3-phosphate (alkylacetyl-GP) phosphohydrolase in rat spleens that catalyzes the conversion of alkylacetyl-GP to alkylacetyl-G. The bulk of the enzymatic activity (53%) is located in the microsomal fraction, whereas 28% of the activity is present in mitochondria. The microsomal enzyme has an optimal pH of 7.0-7.4, an "apparent" Km of 31.8 microM for alkylacetyl-GP, and is widely distributed in various rat tissues. Studies of alkylacetyl-GP phosphohydrolase with respect to substrate specificity, pH profiles, sensitivities to temperature, and effects of detergent, ethanol, or cations indicate the activity of this enzyme can be distinguished from the activities of a nonspecific phosphomonoesterase or phosphatidate phosphohydrolase. Like alkyllyso-GP:acetyl-CoA acetyltransferase, the alkylacetyl-GP phosphohydrolase shows no notable substrate selectivities with regard to variations in alkyl chain length (C16:0 versus C18:0) at the sn-1 position or short chain acyl groups (C2:0 to C6:0, with the exception of C3:0) at the sn-2 position of the glycerol moiety. The enzymatic activity of alkylacetyl-GP phosphohydrolase is 30-90-fold higher than alkyllyso-GP:acetyl-CoA acetyltransferase in most tissues examined. Even though alkyllyso-GP is a substrate for alkyllyso-GP:acetyl-CoA acetyltransferase, it can also be degraded by alkylacetyl-GP phosphohydrolase. Thus, our findings coupled with earlier results imply that specificities of the molecular species of platelet-activating factor synthesized de novo are determined by the enzyme involved in the final step of this pathway, the dithiothreitol-insensitive alkylacetyl-G:CDP-choline cholinephosphotransferase. Furthermore, alkyl-lyso-GP:acetyl-CoA acetyltransferase appears to be the rate-limiting step in the de novo synthesis of alkylacetyl-G.     

Novel 1,3,4-thiadiazolium-2-phenylamine chlorides derived from natural piperine as trypanocidal agents: chemical and biological studies

We herein describe the synthesis and characterization of nine new 1,3,4-thiadiazolium-2-phenylamine chlorides derived from natural piperine. We evaluate their toxic effects against the different evolutive forms of Trypanosoma cruzi, and the host cell (murine macrophages). The results obtained show that mesoionic hydrochloride MI possesses the best activity profile. Compound MI may be a prototype for use in the development of a new chemotherapeutic agent with high efficiency, which may be employed in the treatment of Chagas' disease.     

Acylation of carbohydrates over Al2O3: preparation of partially and fully acylated carbohydrate derivatives and acetylated glycosyl chlorides

Selective and per-O-acylation of carbohydrate derivatives using acyl chlorides and Al2O3, a solid support reagent, is reported. This protocol does not require the addition of any base or activator. This methodology has been further extended to the selective acylation of carbohydrate diols and the one-pot preparation of acetylated glycosyl chlorides direct from free reducing sugars. The yields obtained in most of the cases are excellent.     

Antimicrobial activity of N-alkoxycarbonylmethyl-N-alkyl-piperidinium chlorides

The aim of the study was to assay antibacterial and antifungal activity of newly synthesised N-alkoxycarbonylmethyl-N-alkyl-piperidinium chlorides. The compounds tested were found to inhibit the growth of some Gram-negative bacteria, Gram-positive strains and some representatives of yeast-type Candida. From microbiological experiments two of the compounds tested, N-dodecyloxycarbonylmethyl-N-methyl-piperidinium chloride (3) and N-dodecyl-N-ethoxycarbonylmethyl-piperidinium chloride (6), emerged as more active than the other compounds. Since the resistance of biofilms to biocides should be noted during the design and testing of new antimicrobial agents therefore, we have analysed antibacterial properties of the most active compounds towards biofilms. Our study focused on strains of Pseudomonas aeruginosa and Staphylococcus aureus that served as main model organisms for the biofilm studies.     

Synthesis and biological evaluation of 5-fatty-acylamido-1, 3, 4-thiadiazole-2-thioglycosides

In the present study, the synthesis of 1, 3, 4-thiadiazole-based thioglycosides were accomplished in good yields with employing a convergent synthetic route. The starting material 5-amino-1, 3, 4-thiadiazole-2-thiol and followed by a series of 5-fatty-acylamido-1, 3, 4-thiadiazole-2-thiols (4a–4j) were synthesized with different fatty acid chlorides. The glycosylation of compounds 4a–4j were achieved with trichloroacetimidate methodology. Antimicrobial and cytotoxicity activities of title compounds were evaluated. Among the entire compounds lauric acid and myristic acid derivatives showed good and moderate antimicrobial activity. In case of cytotoxicity results of compounds 8a–8j and 9a–9j, the acetate protected short chain (C6:0, C8:0, C10:0) compounds and the free hydroxyl long chain saturated (C16:0, C18:0) and unsaturated (C18:1, C22:1) compounds exhibited good activity against different cancer cell lines. Further, the free hydroxyl compounds 9a, 9c–9j did not show any toxicity towards normal CHO-K1 cell line whereas acylated compounds 8a–8j exhibited toxicity.     

Simple synthetic procedure for 2'- and 3'-tetrahydropyranyl ribonucleoside derivatives involving regioselective acylation with acyl chlorides, and synthesis of ribonucleotide oligomers

Acylation of ribonucleosides through acyl chlorides in pyridine was induced with high regioselectivity under a controlled condition to give the corresponding 2',5'-diacylates in excellent yields and 2'-acylates, depending on the amount of the acyl chlorides used. On the other hand, a treatment of these resulting acylates on a silica gel (Wakogel C-300, Wako Pure Chemical Co. Ltd.) conducted their transformation into the corresponding 3',5'-diacylates or 3'-acylates effectively. These resulting 2',5'- and 3',5'-diacylates were further derived, by the known method, into the 3'- and 2'-O-tetrahydropyran-2-yl ribonucleoside derivatives, respectively, with which some ribonucleotide oligomer syntheses have been performed.     

Effects of 3-(2-alkoxyphenylcarbamoyloxy)chinuclidium chlorides on repair-deficient strains ofChlamydomonas reinhardtii

The effect of five 3-(2-alkoxyphenylcarbamoyloxy)chinuclidium chlorides (alkoxy = butoxy-octyloxy) on survival of a wild-type strain and repair-deficient strains ofChlamydomonas reinhardtii was studied. There was a direct relationship with increased toxic effects in the algal strains as a function of the elongation of the alkyl chain of the alkoxy substituents of the phenylcarbamate acid derivatives. Repairdeficient strains were more sensitive than the wild-type strain. The recombination-deficient strain uvs10 expressed the highest sensitivity to the test agents. This suggests that a gene responsible for recombination repair is involved in an important role in DNA repair of damages induced inC. reinhardtii by the phenylcarbamic esters.     

Synthesis and antimicrobial activity of 3-arylamino-1-chloropropan-2-ols

A series of nine 3-arylamino-1-chloropropan-2-ols 2a-2i were synthesized and their anti-fungal activity against pathogenic strains of Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger and Candida albicans, and antibacterial activity against four pathogenic bacterial strains of Salmonella typhi, Pseudomonas aeruginosa, Streptococcus pneumonae and Staphylococcus aureus were evaluated using different assay systems. 1-Chloro-3-(4'-chlorophenylamino)-propan-2-ol was found to be the most active anti-fungal compound against three pathogenic strains under study, i.e., A. fumigatus, A. flavus and A. niger; the compound showed more than 90% inhibition of growth of A. fumigatus at a concentration of 5.85 microg/ml in disc diffusion assay. Interestingly, 1-chloro-3-(4'-chlorophenylamino)-propan-2-ol did not show any toxicity up to a concentration of 4000 microg/ml. Although 1-chloro-3-(4'-chlorophenylamino)-propan-2-ol was about 8 times less active than the standard compound amphotericin B, its toxicity was many more fold less than the toxicity of amphotericin B. Further, 1-chloro-3-(2',6'-dichlorophenylamino)-propan-2-ol and 1-chloro-3-(3',5'-dichlorophenylamino)-propan-2-ol were found to be the most active compounds against C. albicans. In the anti-microbial assay, 1-chloro-3-(2',4'-dichlorophenylamino)-propan-2-ol and 1-chloro-3-(3',5'-dichlorophenylamino)-propan-2-ol were found to be the most active compounds against Salmonella typhi and 1-chloro-3-(3',4'-dichlorophenylamino)-propan-2-ol was found to be the most active compound against P. aeruginosa. Although, the activities of 1-chloro-3-(2',4'-dichlorophenylamino)-propan-2-ol and 1-chloro-3-(3',5'-dichlorophenylamino)-propan-2-ol are about half the activity of the standard anti-bacterial compound tetracycline, these compounds also were many fold less toxic than the standard drug.     

The action of 1-alkyl-1-nitrosoureas and 1-alkyl-3-nitro-1-nitrosoguanidines on the M1 generation of barley andArabidopsis thaliana (L.) heynh.

The activity of 1-methyl-1-nitrosourea (MNH), 1-ethyl-1-nitrosourea (ENH), 1-methyl-3-nitro-1-nitrosoguanidine (MNG) and 1-ethyl-3-nitro-1-nitrosoguanidine (ENG) was tested on seeds of barley andArabidopsis. The activity of nitrosoamides tested was expressed by the germination and M₁ seedling height reduction of barley and M₁ root length reduction ofArabidopsis.

1. 1)
   After the action of both nitrosoureas (MNH and ENH) the germination of barley is at the same level as that of controls, even at concentrations, leading to a maximal reduction in the height of seedlings. After the action of both nitrosoguanidines (MNG and ENG) germination decreases in parallel with the decreasing seedling height. InArabidopsis no such differences in the relation germination to root length reduction were observed after nitrosoureas and nitrosoguanidines treatment. The differences in the M₁ generation of barley andArabidopsis after nitrosoguanidines treatment may be the reason for the non-mutagenic action of MNG and ENG in barley.     
   
   

Synthesis and biological evaluation of novel 6-substituted 5-alkyl-2-(arylcarbonylmethylthio)pyrimidin-4(3H)-ones as potent non-nucleoside HIV-1 reverse transcriptase inhibitors

A novel series of 2-arylcarbonylmethylthio-6-arylmethylpyrimidin-4(3H)-ones have been synthesized and evaluated for in vitro anti-HIV activities in MT-4 cells. Most of these new compounds showed moderate to potent activities against wild-type HIV-1 with an EC(50) range from 8.97 microM to 0.010 microM. Among them, the 6-(3,5-dimethylbenzyl) analogue 5p was identified as the most promising compound (EC(50)=0.010 microM, SI>31,800) associated with moderate activity against the HIV-1 double mutant RT strain K103N+Y181C. The structure-activity relationships of these new congeners were further discussed.