Antioxidant and anticancer activities of novel p-alkylaminophenols and p-acylaminophenols (aminophenol analogues)

Novel compounds were designed based on fenretinide, N-(4-hydroxyphenyl)retinamide (2), which is a synthetic amide of all-trans-retinoic acid (1) that is a potent antioxidant and anticancer agent. Our recent findings indicated that antioxidant and anticancer activities were due to p-methylaminophenol moiety (8) in 2, and that p-octylaminophenol (7), which has an elongated alkyl chain, was more potent than 8. This finding lets us to investigate whether compounds containing alkyl or acyl chains linked to an aminophenol residue as long as 2 and 1, would show activities greater than 2. For this purpose, we prepared p-dodecanoylaminophenol (3), p-decanoylaminophenol (4), p-dodecylaminophenol (5), and p-decylaminophenol (6). The p-alkylaminophenols, 5 and 6, exhibited superoxide scavenging activities, but not p-acylaminophenols, 3 and 4. Elongation of the alkyl chain length reduced superoxide trapping capability (8>7>6>5). In contrast, lipid peroxidation in rat liver microsomes was reduced by 5 and 6 in dose-dependent manner. Compounds 3 and 4 were poor lipid peroxidation inhibitors, being approximately 400- to 1300-fold lower than 5 and 6. In addition, all compounds inhibited cell growth of human leukemia cell lines, HL60 and HL60R, in dose-dependent manners (5>6>3=4). The HL60R cell line is resistant against 1. Growth of both cell lines was suppressed by 5 and 6 in a fashion dependent on the length of the aminophenol alkyl chain, but not by 3 and 4. These results indicate that 5, a potent anticancer agent greater than 2, may potentially have clinical utility, and that its anticancer activity is correlated with inhibitory potency against lipid peroxidation, but not with superoxide scavenging activity.     

Comparative study of oestrogenic properties of eight phytoestrogens in MCF7 human breast cancer cells

Previous studies have compared the oestrogenic properties of phytoestrogens in a wide variety of disparate assays. Since not all phytoestrogens have been tested in each assay, this makes inter-study comparisons and ranking oestrogenic potency difficult. In this report, we have compared the oestrogen agonist and antagonist activity of eight phytoestrogens (genistein, daidzein, equol, miroestrol, deoxymiroestrol, 8-prenylnaringenin, coumestrol and resveratrol) in a range of assays all based within the same receptor and cellular context of the MCF7 human breast cancer cell line. The relative binding of each phytoestrogen to oestrogen receptor (ER) of MCF7 cytosol was calculated from the molar excess needed for 50% inhibition of 3H]oestradiol binding (IC50), and was in the order coumestrol (35x)/8-prenylnaringenin (45x)/deoxymiroestrol (50x)>miroestrol (260x)>genistein (1000x)>equol (4000x)>daidzein (not achieved: 40% inhibition at 10(4)-fold molar excess)>resveratrol (not achieved: 10% inhibition at 10(5)-fold molar excess). For cell-based assays, the rank order of potency (estimated in terms of the concentration needed to achieve a response equivalent to 50% of that found with 17beta-oestradiol (IC50)) remained very similar for all the assays whether measuring ligand ability to induce a stably transfected oestrogen-responsive ERE-CAT reporter gene, cell growth in terms of proliferation rate after 7 days or cell growth in terms of saturation density after 14 days. The IC50 values for these three assays in order were for 17beta-oestradiol (1 x 10(-11)M, 1 x 10(-11)M, 2 x 10(-11)M), and in rank order of potency for the phytoestrogens, deoxymiroestrol (1 x 10(-10)M, 3 x 10(-11)M, 2 x 10(-11)M)>miroestrol (3 x 10(-10)M, 2 x 10(-10)M, 8 x 10(-11)M)>8-prenylnaringenin (1 x 10(-9)M, 3 x 10(-10)M, 3 x 10(-10)M)>coumestrol (3 x 10(-8)M, 2 x 10(-8)M, 3 x 10(-8)M)>genistein (4 x 10(-8)M, 2 x 10(-8)M, 1 x 10(-8)M)/equol (1 x 10(-7)M, 3 x 10(-8)M, 2 x 10(-8)M)>daidzein (3 x 10(-7)M, 2 x 10(-7)M, 4 x 10(-8)M)>resveratrol (4 x 10(-6)M, not achieved, not achieved). Despite using the same receptor context of the MCF7 cells, this rank order differed from that determined from receptor binding. The most marked difference was for coumestrol and 8-prenylnaringenin which both displayed a relatively potent ability to displace [3H]oestradiol from cytosolic ER compared with their much lower activity in the cell-based assays. Albeit at varying concentrations, seven of the eight phytoestrogens (all except resveratrol) gave similar maximal responses to that given by 17beta-oestradiol in cell-based assays which makes them full oestrogen agonists. We found no evidence for any oestrogen antagonist action of any of these phytoestrogens at concentrations of up to 10(-6)M on either reporter gene induction or on stimulation of cell growth.     

Mutagenic activity of 6-aminoquinoxalines in Salmonella typhimurium

Mutagenicity of 6-aminoquinoxaline derivatives was tested with Salmonella typhimurium strains Ta98 and TA100 in the presence and absence of S9 mix from the viewpoint that the 6-aminoquinoxaline skeleton is a common unit of mutagenic imidazoquinoxalines. We tested nine compounds: 5-methyl-6-methylaminoquinoxaline (1), 3,5-dimethyl-6-methylaminoquinoxaline (2), 2,5-dimethyl-6-metnylaminoquinoxaline (3), 6-methylamino-2,3,5-trimethylquinoxaline (4), 2,3-diethyl-5-methyl-6-methylaminoquinoxaline (5), 5-methyl-6-methylamino 3-phenylquinoxaline (6), 6-amino-2,3,5-trimethylquinoxaline (7), 6-dimethylamino-2,3-5-trimethylaminoquinoxaline (8), 6-amino-2,3-dimethylquinoxaline (9). These compounds showed the mutagenic activity for both TA98 and TA100 in the presence of S9 mix, where they were more sensitive for TA100 strain. Methyl groups at the 2, 3 and/or 5 positions increased the potency of mutagenicity (1 < 2 < 3 ⪡ 4, 9 < 7). However, ethyl groups at the 2 and 3 positions lowered the mutagenicity of the methyl substitute but elevated it of the parental compound (1 < 5 < 4). A methyl group at the N⁶ position decreased the mutagenicity (7 > 4 > 8).     

Penile erection and yawning induced by oxytocin and related peptides: structure-activity relationship

The potency of several oxytocin-related peptides in inducing penile erection and yawning after injection into a lateral ventricle of male rats was compared. Substitution of two amino acids in the oxytocin molecule or deletion of the C-terminal glycinamide as in des-GlyNH2-oxytocin [oxytocin(1-8)] reduced oxytocin potency in inducing both effects, the rank order being: oxytocin greater than [Thr4,Gly7]-oxytocin congruent to isotocin [( Ser4,Ile8]-oxytocin) greater than vasopressin [( Phe3,Arg8]-oxytocin) greater than des-GlyNH2-oxytocin. Oxytocin's ability to induce penile erection and yawning was abolished by permanent opening of the disulfide bridge by reduction and carboxymethylation. Oxytocin(1-6) and oxytocin(7-9) were also inactive. Penile erection and yawning induced by oxytocin-related peptides were antagonized in a dose-dependent manner by nonapeptide antagonists with a rank order of potency that follows their antioxytocic activity (d[(CH2)5Tyr(Me)Orn8]-vasotocin congruent to [Pen1,Phe(Me)2,Thr4,Orn8]-oxytocin greater than d[(CH2)5Tyr(Me)Arg8]-vasopression). Carboxymethylated oxytocin, oxytocin(1-6), and oxytocin(7-9) were devoid of antagonistic activity. The present results suggest that central oxytocin receptors mediating the expression of penile erection and yawning are structurally related to those present in the uterus and in the mammary gland.     

The effects and comparative differences of neutrophil specific chemokines on neutrophil chemotaxis of the neonate

Neutrophil specific chemokines are potent chemoattractants for neutrophils. IL-8/CXCL8 is the most extensively studied member of this group, and its concentrations increase during inflammatory conditions of the newborn infant including sepsis and chronic lung disease. A significant amount of information exists on the effects of IL-8/CXCL8 on neutrophil chemotaxis of neonates, but little is known about the other neutrophil specific chemokines. The aim of this study was to determine the relative potency of the neutrophil specific chemokines on chemotaxis of neonatal neutrophils and to compare this effect with the effect on adult neutrophils. Neutrophils were isolated from cord blood or healthy adult donors and incubated in a Neuroprobe chemotaxis chamber. Chemokine concentrations ranging from 1-1000 ng/mL were used. Differences in chemotactic potency existed among the seven neutrophil specific chemokines. Specifically, at 100 ng/mL, the order was IL-8/CXCL8>GRO-alpha/CXCL1>GCP-2/CXCL6>NAP-2/CXCL7>ENA-78/CXCL5>GRO-gamma/CXCL2>GRO-beta/CXCL3. This pattern was observed for adult and neonatal neutrophils. We conclude that (1) neutrophils from cord blood exhibit the same pattern of potency for each ELR chemokine as neutrophils from adults, and (2) migration of neonatal neutrophils is significantly less than that of adults at every concentration examined except the lowest (1 ng/mL).     

Tyrosinase inhibitory lignans from the methanol extract of the roots of Vitex negundo Linn. and their structure-activity relationship.

Phytochemical investigation of the methanol extract of Vitex negundo afforded eight lignans; negundin A 1, negundin B 2, 6-hydroxy-4-(4-hydroxy-3-methoxy)-3-hydroxymethyl-7-methoxy-3,4-dihydro-2-naphthaledehyde 3, vitrofolal E 4, (+)-lyoniresinol 5, (+)-lyoniresinol-3alpha-O-beta-d-glucoside 6, (+)-(-)-pinoresinol 7, and (+)-diasyringaresinol 8. The structures of these compounds were elucidated unambiguously by spectroscopic methods including 1D and 2D NMR analysis and also by comparing experimental data with literature data. The tyrosinase inhibitory potency of these compounds has been evaluated and attempts to justify their structure-activity relationships have been made in the present work. The compound 5 was found to be the most potent (IC(50)=3.21 microM) while other compounds demonstrated moderate to potent inhibitions. It was found that the substitution of functional group(s) at C-2 and C-3 positions and the presence of the -CH(2)OH group plays a vital role in the potency of the compounds. The compound 5 can act as a potential lead molecule to develop new drugs for the treatment of hyperpigmentation associated with the high production of melanocytes.     

Synthesis and pharmacology of the isomeric methylheptyl-Δ-tetrahydrocannabinols

The synthesis of the 3-heptyl, and the eleven isomeric 3-methylheptyl-Δ⁸-tetrahydrocannabinols (3–7, R and S methyl epimers, and 8) has been carried out. The synthetic approach entailed the synthesis of substituted resorcinols, which were subjected to acid catalyzed condensation with trans-para-menthadienol to provide the Δ⁸-THC analogue. The 1′-, 2′- and 3′-methylheptyl analogues (3–5) are considerably more potent than Δ⁸-THC. The 4′-, 5′- and 6′-methylheptyl isomers (6–8) are approximately equal in potency to Δ⁸-THC.     

Study on the mutagenicity of nifurtimox and eight derivatives with the L-arabinose resistance test of Salmonella typhimurium

The mutagenicity of nifurtimox (nfx) and 8 nfx analogues has been investigated with the L-arabinose forward-mutation assay of Salmonella typhimurium. The nfx analogues tested were obtained by replacing the 3-methyl-4-yl-tetrahydro-1,4-thiazine-1,1-dioxide group of the parent compound with the following other groups: indazol-1-yl (1); pyrazol-1-yl (2); benzimidazol-1-yl (3); 1,2,4-triazol-4-yl (4); 1-methyl-3-methylthio-1,2,4-triazol-4-yl-5-thione (5); 3,5-bis(methylthio)-1,2,4-triazol-4-yl (6); 1-adamantyl (7); 4,6-diphenylpyridin-1-yl-2-one (8). The mutagenic activity of each chemical was determined by the standard plate-incorporation test, in the presence or absence of the S9 activation mixture. The 9 compounds were mutagenic and exhibited linear dose-mutagenic response relationships. They were direct-acting mutagens and showed a nearly 1000-fold range in mutagenic potency from chemical 1 to nfx. In most cases, the addition of S9 mixture to the test plates decreased the mutagenicity of compounds. This effect was particularly noticeable in the case of chemicals 1-3, 5 and 7 where a more than 70% decrease in mutagenic activity was observed in the presence of the S9 mixture. The mutagenic potency of compounds in the Ara test showed a negative linear correlation with previously reported antitrypanosomal activity. Thus, chemicals 6 and 8 with in vitro activities against Trypanosoma cruzi clearly superior to that of nfx showed 2 of the lowest mutagenic potencies in the Ara test and these were only somewhat higher than the mutagenicity of the reference drug.     

Metalloporphyrin probes for antimalarial drug action

Metal-substituted protoporphyrin IXs (Co(III)PPIX (1), Cr(III)PPIX (2), Mn(III)PPIX (3), Cu(II)PPIX (4), Mg(II)PPIX (5), Zn(II)PPIX (6) and Sn(IV)PPIX (7)), phthalocyanine tetrasulfonates (PcS (8) and Ni(II)PcS (9)), and anionic and cationic porphyrins (meso-tetra(4-sulfonatophenyl)porphine (TPPS4, 10), meso-tetra(4-carboxyphenyl)porphine (TPPC4, 11), tetrakis(4-N-trimethylaminophenyl)porphine (TMAP, 12) and meso-tetra(N-methyl-4-pyridyl)porphine (TMPyP4, 13)) have been used as probes to compare two different assays for the inhibition of beta-hematin formation. The results demonstrate that the efficacy of these probes in either the beta-hematin inhibition assay (9, 7, 6, 5>4>11, 3>10, 8>2, 1; 12 and 13 did not inhibit.) or the bionucleating template assay (8>1>11>9, 2>4>3>7>10>5>6; 12 and 13 did not inhibit.) differ significantly. These differences are examined in light of possible interactions between the inhibitor probes, heme, beta-hematin and the bionucleating template. This detailed analysis highlights the fact that while dominant modes of interactions may be occasionally identified, the precise mechanism of inhibition undoubtedly consists of the interplay between multiple interactions.     

Comparison of spantide II and CP-96,345 for blockade of tachykinin-evoked contractions of smooth muscle.

CP-96,345, a quinuclidine, is a potent inhibitor of substance P for the NK1 receptor of bovine brain, but has reduced potency for the corresponding receptor of the rat and mouse, and none for NK2 or NK3 receptors. A related quinuclidine showed similar but lower potency than CP-96,345 for NK1. CP-96,345 was more potent than the spantide I of 1984, D-Arg1,Pro2,Lys3,Pro4,Gln5,Gln6,D-Trp7,Phe8,D-Trp9, Leu10,Leu11,NH2. Our continued designs for antagonists of substance P led to spantide II in 1990 which is: D-NicLys1,Pro2,3-Pal3,Pro4,D-Cl2Phe5,Asn6,D-Trp7 ,Phe8,D-Trp9,Leu10,Nle11-NH2. The pA2 values of spantide II and CP-96,345 for guinea pig taenia coli were 7.6 and 6.8, respectively. The pIC50 values for blockade of tachykinin-mediated neurotransmission in the rabbit iris sphincter were 6.1 and 5.4, respectively. Spantide II was nearly 10 times more potent than CP-96,345 in these two assays.     

Design and synthesis of methyl 2-methyl-7,7-dihalo-5-phenyl-2-azabicyclo[4.1.0]hept-3-ene-4-carboxylates with calcium channel antagonist activity

A group of methyl 2-methyl-7,7-dihalo-5-(substituted-phenyl)-2-azabicyclo[4.1.0]hept-3-ene-4-carboxylates were prepared by reaction of dihalocarbenes (:CX2, X = Br, Cl) with methyl 1-methyl-4-(substituted-phenyl)-1,4-dihydropyridine-3-carboxylates. In vitro calcium channel antagonist activities were determined using a guinea pig ileum longitudinal smooth muscle assay. The title compounds exhibited weaker CC antagonist activity (10(-5)-10(-6)M range) than the reference drug nifedipine (1.4 x 10(-8)M). Structure-activity relationship studies showed that the position of a nitro substituent on the C-5 phenyl ring where the relative potency order was ortho > meta > para, and the size and/or electronegativity of the C-7 geminal-dihalo substituents (Br > Cl), were determinants of calcium channel antagonist activity. This class of compounds did not exhibit any inotropic effect on guinea pig left atria. A dihalocyclopropyl moiety is a potential bioisostere for the 2-methyl-3-methoxycarbonylvinyl moiety present in the calcium channel antagonist nifedipine.     

Prostatectomie radicale rétropubienne avec préservation nerveuse. Technique et résultats à propos de 200 cas

Objectives

Nerve-sparing radical retropublic prostatectomy carries a risk of leaving positive posterolateral margins with controversial potency recovery rates. We analyses the potency recovery rate and the incidence of positive surgical margins observed with the nerve-sparing procedure in 200 cases.

Methods

Between 1990 and 2000, 605 patients underwent radical retropubic prostatectomy; 200 consecutive potent patients were selected for nerve-sparing: bilateral (87%), unilateral (13%). Mean age was 61.7, mean PSA was 10.48, clinical stage: T1 (41%) T2 (59%), Gleason score: 2 to 6 (81%) 7 to 8 (19%). Specimens were step-sectioned for histological examination, according to the Stanford protocol. Erectile function was evaluated before surgery and postoperatively every 3 months for 2 years. Only patients who achieved unassisted intercourse were considered to be potent.

Results

Positive surgical margins were found in 35 (17%) patients and identified at the nerve-sparing site in 8 (4%) patients. Overall, 157 patients were followed for two years and recovery of potency was observed in 70% of them. On multivariate analysis, the most significant factors affecting postoperative potency were preoperative erectile function and extent of nerve sparing, bilateral versus unilateral; age was not significant.

Conclusions

Nerve-sparing techniques in radical retropubic prostatectomy carry a very low incidence of positive posterolateral margins and yield favorable results in terms of potency recovery.     

Muscarinic receptor binding activity of polyoxygenated flavones from Melicope subunifoliolata

The bark extract of Melicope subunifoliolata (Stapf) T.G. Hartley showed competitive muscarinic receptor binding activity. Six polymethoxyflavones [melibentin (1); melisimplexin (3); 3,3',4',5,7-pentamethoxyflavone (4); meliternatin (5); 3,5,8-trimethoxy-3',4',6,7-bismethylenedioxyflavone (6); and isokanugin (7)] and one furanocoumarin [5-methoxy-8-geranyloxypsoralen (2)] were isolated from the bark extract. Compounds 2 and 6 were isolated for the first time from M. subunifoliolata. The methoxyflavones (compounds 1, 3, 4, 5, 6, and 7) show moderate inhibition in a muscarinic receptor binding assay, while the furanocoumarin (compound 2) is inactive. The potency of the methoxyflavones to inhibit [(3)H]NMS-muscarinic receptor binding is influenced by the position and number of methoxy substitution. The results suggest these compounds are probably muscarinic modulators, agonists or partial agonists/antagonists.     

Design of novel bicyclic analogues derived from a potent oxytocin antagonist.

Eleven new analogues were synthesized by modification of the potent oxytocin antagonist (OTA) [(S)Pmp(1), D-Trp(2), Pen(6), Arg(8)]-Oxytocin, or PA (parent antagonist), in which (S)Pmp = beta,beta-(3-thiapentamethylene)-beta-mercapto-propionic acid. By internal acylation of Lys, Orn, L-1,4-diaminobutyric acid (Dab), L-1,3-diaminopropionic acid (Dap) at position 4 with the C-terminal Gly of the peptide tail, we prepared cyclo-(4-9)-[Lys(4), Gly(9)]-PA (pA(2) = 8.77 +/- 0.27), 1, and cyclo-(4-9)-[Orn(4), Gly(9)]-PA (pA(2) = 8.81 +/- 0.25), 3, which are equipotent with PA (pA(2) = 8.68 +/- 0.18) in the rat uterotonic assay and cyclo-(4-9)-[Dab(4), Gly(9)]-PA, 4, cyclo-(4-9)-[Dap(4), Gly(9)]-PA, 5, and cyclo-(4-9)-[Pmp(1), Lys(4), Gly(9)]-PA, 2, which were weaker OTAs. Neither 1 nor 3 had activity as agonists or antagonists in the antidiuretic assay. In the pressor assay, both analogues 1 and 3, with pA(2) = 7.05 +/- 0.10 and pA(2) = 6.77 +/- 0.12, respectively, are somewhat weaker antagonists than PA (pA(2) = 7.47 +/- 0.35) showing significant gain in specificity. The [desamido(9)] PA-ethylenediamine monoamide, 6, and the dimer ([desamido(9)]-PA)(2) ethylenediamine diamide, 7, had lower potency in the uterotonic assay than PA. Additionally, we synthesized cyclo-(1-5)-[(HN)Pmp(1), Asp(5)]-PA, 8, inactive in all tests, which suggests that the intact Asn(5) side chain may be critical in the interaction of the OTAs with the oxytocin (OT) receptor. Similarly, cyclo-(5-9)-[Dap(5), Gly(9)]-PA, 9, had very low uterotonic potency. Two derivatives of PA truncated from the C-terminus were internally cyclized to Lys(4), giving rise to cyclo-(4-8)-desGly-NH(2)(9)[Lys(4), Arg(8)]-PA, 10 (pA(2) = 8.35 +/- 0.20), which maintains the high potency of PA and has no activity in the rat antidiuretic assay, and in the rat pressor assay it is about ten times weaker (pA2 = 6.41 +/- 0.15) than PA (pA2 = 7.47 +/- 0.35), thus showing gains in specificity, and to cyclo-(4-7)-desArg-Gly-(NH)(2)(8-9)[Lys(4), Pro(7))-PA, 11, which has much weaker potency than PA. Synthesis of cyclo-(4-6)-desPro-Arg-Gly-(NH)(2)(7-9)[Lys(4)]-PA failed.     

Alkylxanthines: inhibition of adenosine-elicited accumulation of cyclic AMP in brain slices and of brain phosphodiesterase activity.

A series of 1, 3-dialkylxanthines was examined as antagonists of adenosine-induced accumulation of cyclic AMP in guinea pig cerebral cortical slices and as inhibitors of brain phosphodiesterases. The order of potency as adenosine-antagonists was: 8-phenyltheophylline (IC₅₀ 6 μM) > 1, 3-dibutylxanthine (IC₅₀ 30 μM), 1, 3-dipropylxanthine > theophylline (IC₅₀ 60 μM), 3-isobutyl-1-methylxanthine (IBMX), 1, 3, 7-triethylxanthine > 7-benzyl IBMX (IC₅₀ 100 μM), 8-methyl IBMX > 7-benzyl-8-bromo IBMX, 9-methyl IBMX, 8-bromo IBMX, 1-isoamyl-3-isobutylxanthine. The order of potency as inhibitors of brain calcium-dependent phosphodiesterase was: 7-benzyl IBMX (IC₅₀ 1.5 μM), 7-benzyl-8-bromo IBMX > 8-methyl IBMX (IC₅₀ 4.5 μM) > IBMX (IC₅₀ 7.5 μM), 8-bromo IBMX > 9-methyl IBMX (IC₅₀ 40 μM), 1, 3, 7-triethylxanthine > 1, 3-dibutylxanthine (IC₅₀ 100 μM), 1-isoamyl-3-isobutylxanthine > theophylline. 8-Phenyltheophylline and 1, 3-dibutylxanthine represented potent adenosine-antagonists with relatively low activity as phosphodiesterase inhibitors whereas 7-benzyl IBMX and 7-benzyl-8-bromo-IBMX were potent inhibitors of the calcium-dependent phosphodiesterase with relatively low activity as adenosine-antagonists. None of the compounds were potent inhibitors of the brain calcium-independent phosphodiesterase, although 1-isoamyl-3-isobutylxanthine might prove useful as an inhibitor of this enzyme because of its very low activity as an adenosine-antagonist.     

Amide-based derivatives of β-alanine hydroxamic acid as histone deacetylase inhibitors: Attenuation of potency through resonance effects

A library of amide-linked derivatives of β-alanine hydroxamic acid were prepared (2-7) and the activity as inhibitors of Zn(II)-containing histone deacetylases (HDACs) determined in vitro against HDAC1 and the anti-proliferative activity determined in BE(2)-C neuroblastoma cells. The IC(50) values of the best-performing compounds (3-7) against HDAC1 ranged between 38 and 84μM. The least potent compound (2) inhibited a maximum of only 40% HDAC1 activity at 250μM. The anti-proliferative activity of 2-7 at 50μM against BE(2)-C neuroblastoma cells ranged between 57.0% and 88.6%. The structural similarity between the potent HDAC inhibitor trichostatin A (TSA, 1; HDAC1, IC(50) 12nM) and the present compounds (2-7) was high at the Zn(II) coordinating hydroxamic acid head group; and in selected compounds (2, 5), at the 4-(dimethylamino)phenyl tail. The significantly reduced potency of 2-7 relative to 1 underscores the rank importance of the linker region as part of the HDAC inhibitor pharmacophore. Molecular modeling of 1-7 using HDAC8 as the template suggested that the conformationally constrained 4'-methyl group of 1 may contribute to HDAC inhibitor potency through a sandwich-like interaction with a hydrophobic region containing F152 and F208; and that the absence of this group in 2-7 may reduce potency. The close proximity of the 5'-carbonyl oxygen atom in 2-7 to the sulfur atom of Met274 in HDAC8 or the corresponding isobutyl group of Leu274 in HDAC1 may attenuate potency through repulsive steric and dipole-dipole forces. In a unique resonance stabilized form of 2, this interaction could manifest as stronger ion-dipole repulsive forces, resulting in a further decrease in potency. This work suggests that resonance structures of HDAC inhibitors could modulate intermolecular interactions with HDAC targets, and potency.     

Synthesis and SAR of 5-, 6-, 7- and 8-aza analogues of 3-aryl-4-hydroxyquinolin-2(1H)-one as NMDA/glycine site antagonists

A series of 5-, 6-, 7- and 8-aza analogues of 3-aryl-4-hydroxyquinolin-2(1H)-one was synthesized and assayed as NMDA/glycine receptor antagonists. The in vitro potency of these antagonists was determined by displacement of the glycine site radioligand [(3)H]5,7-dicholorokynurenic acid ([(3)H]DCKA) in rat brain cortical membranes. Selected compounds were also tested for functional antagonism using electrophysiological assays in Xenopus oocytes expressing cloned NMDA receptor (NR) 1A/2C subunits. Among the 5-, 6-, 7-, and 8-aza-3-aryl-4-hydroxyquinoline-2(1H)-ones investigated, 5-aza-7-chloro-4-hydroxy-3-(3-phenoxyphenyl)quinolin-2-(1H)-one (13i) is the most potent antagonist, having an IC(50) value of 110 nM in [(3)H]DCKA binding and a K(b) of 11 nM in the electrophysiology assay. Compound 13i is also an active anticonvulsant when administered systemically in the mouse maximum electroshock-induced seizure test (ED(50)=2.3mg/kg, IP).     

Structure-mutagenicity relationship among aminoquinolines, aza-analogues of naphthylamine, and their N-acetyl derivatives

The mutagenicity of 7 positional isomers of aminoquinolines (AQ) and their N-acetyl derivatives (AcAQ) was tested in Salmonella typhimurium TA100 and TA98 in the presence and absence of S9 mix. In a series of aminoquinolines, the order of mutagenic potency in the presence of S9 mix is: 5-AQ greater than 8-AQ greater than 7-AQ greater than 3-AQ greater than 2-AQ much greater than 4-AQ, 6-AQ. The alpha-positional isomers, 5-AQ and 8-AQ, are more mutagenic than the beta-isomer, 2-, 3-, 6-, 7-AQ's. These results are in contrast to the finding that beta-naphthylamine is more mutagenic than alpha-naphthylamine. In a series of N-acetylaminoquinolines, the order of mutagenic potency in the presence of S9 mix is: 7-AcAQ greater than 6-AcAQ greater than 8-AcAQ much greater than all the others. It is suggested that the AQ and AcAQ series might exert their mutagenicity through different molecular mechanisms (i.e., metabolic activation) from each other. The rate of metabolic activation does not seem to be correlated with the mutagenic potency of the compounds. It is noteworthy that 7-AQ and 8-AQ are mutagenic in both the strains tested in the absence of S9 mix.     

Diversity of Rotavirus Strains Causing Diarrhea in <5 Years Old Chinese Children: A Systematic Review

Background

We conducted a systematic review of the diversity and fluctuation of group A rotavirus strains circulating in China.

Methods and Findings

Studies of rotavirus-based diarrhea among children less than 5 years, published in English or Chinese between 1994 and 2012, were searched in PubMed, SinoMed, and CNKI and reviewed by applying standardized algorithms. The temporal and spatial trends of genotyping and serotyping were analyzed using a random-effects model. Ninety-three studies met the inclusion/exclusion criteria and were included in the meta-analysis. Overall, 22,112 and 10,660 rotavirus samples had been examined for G and P types, respectively. The most common G types were G1 (39·5%), G3 (35·6%), G2 (1·3%), and G9 (0·1%). Among P types, P[8] (54·6%) was the predominant type, followed by P[4] (11·1%) and P6 (0·1%). The most common G-P combinations were G3P[8] (32·1%) and G1P[8] (24·5%), followed by G2P[6] (13·2%) and G2P[4] (10·1%). Before 2000, serotype G1 was the predominant strain and accounted for 74·3% of all rotavirus infections; however, since 2000, G3 (45·2%) has been the predominant strain. Rotavirus P types showed little variation over the study period.

Conclusion

Despite the variation of serotypes observed in China, the G1, G2, G3, and G4 serotypes accounted for most rotavirus strains in recent decades. These results suggest that Chinese children will be adequately protected with currently available or forthcoming rotavirus vaccines.     

Allosteric modulators of human A2B adenosine receptor

Background

Among adenosine receptors (ARs) the A_2B subtype exhibits low affinity for the endogenous agonist compared with the A₁, A_2A, and A₃ subtypes and is therefore activated when concentrations of adenosine increase to a large extent following tissue damages (e.g. ischemia, inflammation). For this reason, A_2B AR represents an important pharmacological target.

Methods

We evaluated seven 1-benzyl-3-ketoindole derivatives (7–9) for their ability to act as positive or negative allosteric modulators of human A_2B AR through binding and functional assays using CHO cells expressing human A₁, A_2A, A_2B, and A₃ ARs.

Results

The investigated compounds behaved as specific positive or negative allosteric modulators of human A_2B AR depending on small differences in their structures. The positive allosteric modulators 7a,b and 8a increased agonist efficacy without any effect on agonist potency. The negative allosteric modulators 8b,c and 9a,b reduced agonist potency and efficacy.

Conclusions

A number of 1-benzyl-3-ketoindole derivatives were pharmacologically characterized as selective positive (7a,b) or negative (8c, 9a,b) allosteric modulators of human A_2B AR.

General significance

The 1-benzyl-3-ketoindole derivatives 7–9 acting as positive or negative allosteric modulators of human A_2B AR represent new pharmacological tools useful for the development of therapeutic agents to treat pathological conditions related to an altered functionality of A_2B AR.