Quantitative structure-activity relationship study of new potent and selective antagonists at the 5-HT(1A) and adrenergic alpha(1d) receptors: Derivatives of spiroethyl phenyl(substituted)piperazine

The antagonistic activities of derivatives of spiroethyl phenyl(substituted)piperazine at the 5-HT(1A) and adrenergic alpha(1d) receptors is quantitatively analyzed employing physicochemical and structural parameters. The derived correlation equation revealed that a substituent, other than 2-CH3 in the phenyl ring, having higher molar refraction, MR, and a substituent producing higher positive field effect at the 3-position are beneficial in increasing the binding affinity at the 5-HT(1A) receptor. In addition, a less hydrophobic substituent at the 4-position is also helpful in augmenting the binding affinity. The 5-R substituents which have higher MR values, however, elicit a detrimental effect. Two disubstituted compounds which are not present in the original data-set and have higher theoretical binding affinities are designed from the correlation equation. These compounds consisting of 2-OCH(CH3)2, 3-Cl and 2-C3H7, 3-Cl in the phenyl ring, have theoretical pK(i) values 10.57 and 10.12 respectively. For the adrenergic alpha(1d) receptor, a less bulky group at the 3-position with 5-Cl (or simply a 3-Cl) is advantageous in increasing the binding affinity. Likewise, a substituent exhibiting a less negative resonance effect at the 4-position and the substituent with low polarizability and showing more a negative resonance effect at the 5-position are suitable for enhancement of the binding affinity. The analysis provides the grounds for rationalizing substituent selection in designing better potency antagonists in the series.     

Genotoxicity of the cancer chemopreventive drug candidates CP-31398, SHetA2, and phospho-ibuprofen

The genotoxic activities of three cancer chemopreventive drug candidates, CP-31398 (a cell permeable styrylquinazoline p53 modulator), SHetA2 (a flexible heteroarotinoid), and phospho-ibuprofen (PI, a derivative of ibuprofen) were tested. None of the compounds were mutagenic in the Salmonella/Escherichia coli/microsome plate incorporation test. CP-31398 and SHetA2 did not induce chromosomal aberrations (CA) in Chinese hamster ovary (CHO) cells, either in the presence or absence of rat hepatic S9 (S9). PI induced CA in CHO cells, but only in the presence of S9. PI, its parent compound ibuprofen, and its moiety diethoxyphosphoryloxybutyl alcohol (DEPBA) were tested for CA and micronuclei (MN) in CHO cells in the presence of S9. PI induced CA as well as MN, both kinetochore-positive (Kin+) and -negative (Kin-), in the presence of S9 at ≤100μg/ml. Ibuprofen was negative for CA, positive for MN with Kin+ at 250μg/ml, and positive for MN with Kin- at 125 and 250μg/ml. DEPBA induced neither CA nor MN at ≤5000μg/ml. The induction of chromosomal damage in PI-treated CHO cells in the presence of S9 may be due to its metabolites. None of the compounds were genotoxic, in the presence or absence of S9, in the GADD45α-GFP Human GreenScreen assay and none induced MN in mouse bone marrow erythrocytes.     

Quantitative structure–activity relationship study of new potent and selective antagonists at the 5-HT1A and adrenergic α1d receptors: Derivatives of spiroethyl phenyl(substituted)piperazine

The antagonistic activities of derivatives of spiroethyl phenyl(substituted)piperazine at the 5-HT_1A and adrenergic α_1d receptors is quantitatively analyzed employing physicochemical and structural parameters. The derived correlation equation revealed that a substituent, other than 2-CH₃ in the phenyl ring, having higher molar refraction, MR, and a substituent producing higher positive field effect at the 3-position are beneficial in increasing the binding affinity at the 5-HT_1A receptor. In addition, a less hydrophobic substituent at the 4-position is also helpful in augmenting the binding affinity. The 5-R substituents which have higher MR values, however, elicit a detrimental effect. Two disubstituted compounds which are not present in the original data-set and have higher theoretical binding affinities are designed from the correlation equation. These compounds consisting of 2-OCH(CH₃)₂, 3-Cl and 2-C₃H₇, 3-Cl in the phenyl ring, have theoretical pK_i values 10.57 and 10.12 respectively. For the adrenergic α_1d receptor, a less bulky group at the 3-position with 5-Cl (or simply a 3-Cl) is advantageous in increasing the binding affinity. Likewise, a substituent exhibiting a less negative resonance effect at the 4-position and the substituent with low polarizability and showing more a negative resonance effect at the 5-position are suitable for enhancement of the binding affinity. The analysis provides the grounds for rationalizing substituent selection in designing better potency antagonists in the series.     

Chroman and tetrahydroquinoline ureas as potent TRPV1 antagonists

Novel chroman and tetrahydroquinoline ureas were synthesized and evaluated for their activity as TRPV1 antagonists. It was found that aryl substituents on the 7- or 8-position of both bicyclic scaffolds imparted the best in vitro potency at TRPV1. The most potent chroman ureas were assessed in chronic and acute pain models, and compounds with the ability to cross the blood-brain barrier were shown to be highly efficacious. The tetrahydroquinoline ureas were found to be potent CYP3A4 inhibitors, but replacement of bulky substituents at the nitrogen atom of the tetrahydroisoquinoline moiety with small groups such as methyl can minimize the inhibition.     

Synthesis,Antiproliferative, and Antiviral Evaluation of Certain Acyclic 6-Substituted Pyrrolo[2,3-D]-pyrimidine Nucleoside Analogs Related to Sangivamycin and Toyocamycin

Abstract

A number of 6-substituted 7-[(2-hydroxyethoxy)methyl]pyrrolo[2,3-d]pyrimidine and 7-[(1,3-dihydroxy-2-propoxy)methyl]pyrrolo[2,3-d]pyrimidine derivatives related to the nucleoside antibiotics toyocamycin and sangivamycin were prepared and tested for their biological activity. Treatment of 2-amino-5-bromo-3,4-dicyanopyrrole (2) with triethylorthoformate, followed by alkylation via the sodium salt method with either 2-(acetoxyethoxy)methyl bromide or (1,3-diacetoxy-2-propoxy)methyl bromide, furnished the corresponding N-substituted pyrroles 3a and 3b. These compounds were then smoothly converted to the requisite deprotected 4-amino-6-bromopyrrolo[2,3-d]-pyrimidine-5-carbonitriles 5a and 5b (toyocamycin analogs) by methanolic ammonia. The 6-amino-derivatives were obtained by a displacement of the bromo group with liquid ammonia. Conventional functional group transformations involving the 5-cyano group furnished the 5-carboxamide (sangivamycin) and 5-thioamide analogs. Compounds substituted at the 7-position with a ribosyl moiety were active against human cytomegalovirus (HCMV) at micromolar concentrations, but the apparent activity was not selective. The 7-ribosyl compounds also had no activity against human immunodeficiency virus (HIV), though they were all cytotoxic. The new compounds were also evaluated against HCMV, herpes simplex virus type I (HSV-1), HIV, and also for their ability to inhibit the growth of L1210 murine leukemic cells in vitro. None of these compounds with (2-hydroxyethoxy)methyl substituents or 7-(1,3-dihydroxy-2-propoxy)methyl substituent at N-7 showed significant cytotoxicity toward L1210, or toward uninfected human foreskin fibroblasts (HFF cells), and KB cells. Nor were they cytotoxic in human lines CEM or MT2. Only compound 4a was found to be active against HCMV, having an IC₅₀ of 32 μM.     

Genotoxic activity of newly synthesized derivatives of cyano-pyridone in murine cells in vivo and in vitro

Possible genotoxic activity of two newly synthesized cyanopyridone compounds [4-(N-methyl-phalimidyl-3)-3-cyano-4-methyl-pyridone-2 (MPhCMP) and 1-(4-hydroxyphenyl)-3-cyano-4-methyl-pyridone-2 (HCMP)] with in vitro antitumor activity was studied both in in vitro and in vivo murine test systems. In L5178Y mouse lymphoma cells, HCMP did not induce micronuclei (MN) at the highest available (because of toxicity) concentration (100 microg/ml), while MPhCMP at dose of 50 microg/ml induced 2.6-fold, and at dose of 100 microg/ml 3.95-fold increase of number of the cells with MN. The concentration of 100 microg/ml is a threshold of toxicity of MPhCMP. In experiments on possible DNA damaging activity (the comet assay) of both substances using the same doses as in in vitro mutagenesis assay, we did not reveal any evidence of DNA damage. The acute toxicity of compounds was studied on male Swiss albino mice. LD50 values of MPhCMP and HCMP were 177.5 and 288 mg/kg, respectively. MPhCMP was more potent MN inductor than HCMP (2.5-fold at doses equivalent to 1/2 of LD50). Both substances possessing in vitro antitumor activity along with weak genotoxicity have a good chance for successful in vivo antitumor studies in rodents.     

Synthesis,cytotoxic activity,DNA topoisomerase-II inhibition,molecular modeling and structure–activity relationship of 9-anilinothiazolo[5,4-b]quinoline derivatives

Some novel 9-anilinothiazolo[5,4-b]quinoline derivatives were synthesized and their cytotoxic activities were examined. The inhibition of some of the most active compounds over human topoisomerase II (Topo II) activity was assessed with the kDNA decatenation assay. The novel compounds differ in the substituents attached to the anilino ring, a dialkylamino alkylamino group, a saturated heterocyclic moiety, a methylthio group at position 2 and a fluorine atom present or absent at 7-position. According to the data, compounds with a diethylaminopropylamino group and a chlorine atom at 4′-position of the anilino ring were the most cytotoxic. The molecular models of all compounds indicated a correlation between hydrophobicity and cytotoxic activity although the direction and magnitude of the dipole moment also had a significant influence on its cytotoxicity. The 2-dialkylaminoalkylamino substituent is flexible and is known to facilitate the crossing of cell membranes; thus, this last barrier may be a limiting step in the mechanisms mediating the cytotoxicity. On the other hand, the activity of 2-methylthio derivatives seems to rely more on the electronic effects brought about by the substitution of the aniline ring. The synthesis, cytotoxicity against cancer cell lines, in vitro inhibition of human topoisomerase II, molecular modeling and the preliminary analysis of structure–activity relationships are presented.     

A new class of histamine H(3)-receptor antagonists: synthesis and structure-activity relationships of 7,8,9,10-tetrahydro-6H-cyclohepta[b]quinolines

The synthesis and biological evaluation of novel cycloheptaquinoline antagonists of the human H(3) receptor are described. Two series of compounds, bearing either an amino substituent or an alkyne linker at the 11-position, were investigated. Modifications of the amino substituents, optimization of chain length and the effect of conformational restraints are described. Several compounds with high affinity and selectivity for the H(3) receptor were discovered.     

Protein synthesis inhibition by 8-oxo-12,13-epoxytrichothecenes

The Fusarium mycotoxin, 4-deoxynivalenol, is an abundant, natural contaminant of corn and wheat. 8-Oxo-12,13-epoxytrichothecenes related to 4-deoxynivalenol were synthesized; they either lacked the 7-hydroxyl but contained a hydroxyl at C-4 (7-deoxynivalenol) or lacked substituents at C-3 and C-7 (3,7-dideoxynivalenol). The ability of these synthetic analogs and their acetylated derivatives to inhibit protein synthesis by cultured mammalian cells was compared to that of 4-deoxynivalenol. Whereas the 50% inhibitory dose (ID50) for murine erythroleukemia cells was about 1 microgram/ml for 4-deoxynivalenol and 3,7-dideoxynivalenol, all of the other analogs were at least 10-fold less potent. When tested at their ID50 dose, all of the 8-oxotrichothecenes, except 4-deoxynivalenol and 3,7-dideoxynivalenol, caused polysome 'run-off', indicating that, at this dose, they are inhibitors of polypeptide chain initiation. With 4-deoxynivalenol and 3,7-dideoxynivalenol, polysomes remained at control levels indicating that these toxins prevent polypeptide chain elongation. From these results and comparisons to previous studies of 8-oxo-12,13-epoxytrichothecenes (trichothecolone, trichothecin, nivalenol and fusarenone X), trichothecenes with substituents at both C-3 and C-4 predominantly inhibit polypeptide chain initiation, whereas those lacking one substituent at either site are inhibitors of chain elongation.     

Design, synthesis and biological evaluation of novel 2-methylpyrimidine-4-ylamine derivatives as inhibitors of Escherichia coli pyruvate dehydrogenase complex E1

As potential inhibitors of Escherichia coli pyruvate dehydrogenase complex E1 (PDHc E1), a series of novel 2-methylpyrimidine-4-ylamine derivatives were designed based on the structure of the active site of PDHc E1 and synthesized using 'click chemistry'. Their inhibitory activity in vitro against PDHc E1 and fungicidal activity were examined. Some of these compounds such as 3g, 3l, 3n, 3o, and 5b demonstrated to be effective inhibitors of PDHc E1 from E. coli and exhibited antifungal activity. SAR analysis indicated that both, the inhibitory potency against E. coli PDHc E1 and the antifungal activity of title compounds, could be increased greatly by optimizing substituent groups in the compounds. The structures of substituent group in 5-position on the 1,2,3-triazole and 4-position on the benzene ring in title compounds were found to play a pivotal role in both above-mentioned biological activities. Amongst all the compounds, compound 5b with iodine in the 5-position of 1,2,3-triazole and with nitryl group in the 4-position of benzene ring acted as the best inhibitor against PDHc E1 from E. coli. It was also found to be the most effective compound with higher antifungal activity against Rhizoctonia solani and Botrytis cinerea at the dosage of 100 μg mL(-1). Therefore, in this study, compound 5b was used as a lead compound for further optimization.     

Conformation study of cyclic adenosine-3',5'-monophosphate and some of its derivatives by means of circular dichroism]

Circular dichroism spectra of adenosine and cyclic adenosine-3',5'-monophosphate (cAMP) and their derivatives, having different substituents in 8-position of heterocycle, are studied, cAMP is suggested to have preferable anti-conformation in the solution, while its derivatives with substituents in 8-position of purine base are preferable in sin-conformation. An exception is 8-(beta aminoethylamine-)cAMP, which has an anti-conformation within pH range from 4.5 to 9.5. This is probably due to the formation of intra-molecular ionic bond between cyclophosphate group and aliphatic amino group of 8-position substituent.     

Chromosomal effects of newly identified water pollutants PBTA-1 and PBTA-2 and their possible mother compounds (azo dyes) and intermediates (non-ClPBTAs) in two Chinese hamster cell lines

We performed the in vitro micronucleus (MN) test on 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2-[2-(acetylamino)-4-[N-(2-cyanoethyl)-ethylamino]-5-methoxyphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2), which are newly identified water pollutants from the Nishitakase river in Kyoto, Japan, and on their possible mother compounds (AZO DYE) and intermediates (non-ClPBTAs). We tested these compounds in the absence and presence of S9 mix in two Chinese hamster cell lines CHL and V79-MZ and scored MN, polynuclear and karyorrhectic (PN), and mitotic (M) cells. PBTA-2 in the absence of S9 mix induced the strongest responses in both cell lines. It was also a strong inducer of binucleate cells in PN cells in both cell lines, which suggested that it induced polyploidy. PBTA-1 showed clear positive results only in the absence of S9 mix and only in V79-MZ cells, inducing aneuploidy. In CHL cells AZO DYE-1 significantly induced MN cells in the presence of S9 mix, and AZO DYE-2 induced MN and PN cells, including binucleate cells and cells with a multilobed nucleus, in the absence of S9 mix. In V79-MZ cells, AZO DYE-1 and -2 induced primarily M cells in the presence of S9 mix. 9% of the M cells treated with 50 microg/ml AZO DYE-1 showed endoreduplication. AZO DYE-2 at 200 microg/ml condensed the chromatin in 100% of the cells. The non-ClPBTAs were a bit more cytotoxic than the other compounds and induced a slight increase in MN cells in both cell lines. Some of the chemicals tested induced a characteristic karyomorphology that might reflect abnormal cell division. Abnormalities of cell division could be detected in PN and M cells as well as in MN cells. Structure-activity relationships have also been discussed.     

From mutagenic to non-mutagenic nitroarenes: effect of bulky alkyl substituents on the mutagenic activity of nitroaromatics in Salmonella typhimurium. Part II. Substituents far away from the nitro group

Derivatives of 4-nitrobiphenyl, 4-nitrosobiphenyl, 2-phenyl-5-nitropyridine (2-aza-4-nitrobiphenyl) and 2-nitrofluorene, bearing various alkyl substituents far away from the nitro group (4'-position in nitrobiphenyls, 7-position in 2-nitrofluorenes) were synthesised and tested for mutagenic potency in strains TA98 and TA100 of Salmonella typhimurium. In the absence of S9 in both strains, mutagenicity of all4'-Ad (Ad=adamantyl). Changes of the molecular shape from 'planar' to non-planar caused by the bulk of the introduced substituents (without influencing the twisting of the nitro substituent or the phenyl rings in the biphenyl compounds) may be responsible for this effect by interfering with an efficient intercalation into DNA.A comparison between experimental and theoretical values as calculated from recently developed equations (QSAR) confirmed our previous results (see the preceding paper) that mutagenicity of alkyl-substituted nitroaromatics cannot be predicted by hydrophobicity and LUMO-energies alone without including steric parameters.     

5-Sulfonyl-benzimidazoles as selective CB2 agonists

A novel series of benzimidazole CB2-receptor agonists was synthesized and the structure-activity relationship explored. The results showed agonistic activities with an EC(50) up to 0.5 nM and excellent selectivity (>4000-fold) over the CB1 receptor. The size of the substituent on the 2-position determined the level of agonism, ranging from inverse agonism to partial agonism to full agonism, which was more pronounced for the rat CB2 receptor. A wide variation of sulfonyl substituents at the benzimidazole 5-position was tolerated, which was used to optimize the drug-like properties. This resulted into lead compound 14j that can be used to investigate the potential of a selective, peripherically acting CB2 agonist. The in vitro profile of key compounds is displayed using pie bar charts (VlaaiVis).     

A novel class of apical sodium co-dependent bile acid transporter inhibitors: the 2,3-disubstituted-4-phenylquinolines

A series of 2,3-disubstituted-4-phenylquinolines were prepared and were found to inhibit the apical sodium co-dependent bile acid transporter (ASBT). Alkyl and ester substitution at the 3-position showed comparable activities while substitution at the 2-position was much more sensitive to the nature of the substituent. The synthesis and in vitro potency data are presented for this novel class of compounds.     

1,5-Biaryl pyrrole derivatives as EP1 receptor antagonists: Structure-activity relationships of 4- and 5-substituted benzoic acid derivatives

This paper details the SAR of 1,5-biaryl pyrrole derivatives with substituents in the 2-, 4-, and 5-positions of the benzoic acid group as EP1 receptor antagonists. Substitution at the 2-position was poorly tolerated, whereas only fluorine was tolerated at the 4-position. In contrast, a range of substituents at the 5-position were discovered which enhanced the in vitro affinity and led to compounds with promising oral exposure. Three derivatives showed efficacy in a preclinical model of inflammatory pain when dosed orally to rats.     

Substitution at the 8-position of 3'-deoxy-cyclic ADP-carbocyclic-ribose, a highly potent Ca2+-mobilizing agent, provides partial agonists

We previously showed that 3'-deoxy-cyclic ADP-carbocyclic-ribose (3'-deoxy-cADPcR, 4) is a stable and highly potent analogue of cyclic ADP-ribose (cADPR, 1), a Ca(2+)-mobilizing second messenger. From these results, we designed and synthesized other 3'-modified analogues of cADPcR having a substituent at the 8-position and found that this modification at the 8-position made them partial agonists. Among these compounds, 8-NH(2)-3'-deoxy-cADPcR (10) was identified as a potent partial agonist with an EC(50) value of 17 nM.     

Substituted benzylamino-6-(trifluoromethyl)pyrimidin-4(1H)-ones: a novel class of selective human A-FABP inhibitors

The synthesis and biological evaluation of novel human A-FABP inhibitors based on the 6-(trifluoromethyl)pyrimidine-4(1H)-one scaffold is described. Two series of compounds, bearing either an amino or carbon substituent in the 2-position of the pyrimidine ring were investigated. Modification of substituents and chain length optimization led to novel compounds with low micromolar activity and good selectivity for human A-FABP.     

Synthesis and biological evaluation of 4'-(6,7-disubstituted-2,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-biphenyl-4-ol as potent Chk1 inhibitors

A new series of potent tricyclic pyrazole-based Chk1 inhibitors are described. Analogues disubstituted on the 6- and 7-positions show improved Chk1 inhibition potency compared with analogues with a single substituent on either the 6- or 7-position. Based on the lead compound 4'-(6,7-dimethoxy-2,4-dihydro-indeno[1,2-c]pyrazol-3-yl)-biphenyl-4-ol (2), detailed SAR studies on the 6- and 7-positions were performed. 3'-morpholin-4'-yl-propoxy, pyridin-4'-ylmethoxy, pyridin-3'-ylmethoxy, 2'-(5'-ethyl-pyridin-2'-yl)-ethoxy, pyridin-2'-ylethoxy, (6'-methyl-pyridin-2'-yl)-propoxyethoxy, 2',3'-dihydroxyl-1'-yl-propoxy, and tetrahydro-furan-3'-yloxy have been identified as the best groups on the 6-position when the 7-position is substituted with methoxyl group. Pyridin-2'-ylmethoxy and pyridin-3'-ylmethoxy have been identified as the best substituents at the 7-position while the 6-position bearing methoxyl group. These compounds significantly potentiate the cytotoxicity of DNA-damaging antitumor agents in a cell-based assay and efficiently abrogate the doxorubicin-induced G2/M and the camptothecin-induced S checkpoints, suggesting that their potent biological activities are mechanism-based through Chk1 inhibition.