Inhibition of human leukocyte elastase by N-substituted tripeptide trifluoromethyl ketones

Several tripeptide trifluoromethyl ketones containing non-naturally occurring N-substituted glycine residues at the P2-position are effective human leukocyte elastase (HLE) inhibitors in vitro and possess IC50 values in the submicromolar range. Deletion of the amino acid at the P3-subsite region affords inactive compounds. The trifluoromethyl ketone derivative of valine is the preferred residue at the P1-position; whereas, the corresponding glycine or alpha, alpha-dimethyl glycine analogs result in inactive compounds.

Effects of phorone and/or buthionine sulfoximine on teratogenicity of 5-fluorouracil in mice

Embryotoxicity and teratogenicity of 5-fluorouracil (5-FU) and modulation of its effect by the depletors of glutathione (GSH) were evaluated in mice. Pregnant ICR mice were intraperitoneally (i.p.) injected with 25 mg/kg of 5-FU on day 11 of gestation (vaginal plug = day 0). Mice were pretreated i.p. with 250 mg/kg of phorone, a GSH depleting agent and/or 200 mg/kg of buthionine sulfoximine (BSO, an inhibitor of GSH biosynthesis) 4 hours before dosing with 5-FU. Dams were killed on day 17 of gestation. Fetuses were examined for external malformations, especially limb malformations. Pretreatment with phorone or BSO decreased fetal weight and increased the frequency and severity of oligodactyly induced by 5-FU, as well as the reduction of maternal GSH levels. Combined use of 125 mg/kg phorone and 100 mg/kg BSO i.p. augmented growth retardation induced with 5-FU. Cotreatment with exogenous GSH, at a dose of 300 mg/kg injected intravenously, could not suppress the augmentative effects of phorone and/or BSO on 5-FU teratogenicity under these experimental conditions. These results indicate that the level of endogenous GSH is one of the factors which significantly affects teratogenicity of 5-FU.

In vitro biocompatibility of polyetheretherketone and polysulfone composites

Short carbon fiber reinforced composites could potentially replace some of the metal alloys used in orthopedic implants. In particular, polysulfone and, more recently, polyetheretherketone have been considered as the matrix material for carbon fiber reinforced composite implant materials. ASTM standards F813 and F619 for direct contact cell culture evaluation and extraction were employed to determine the in vitro biocompatibility of a carbon fiber composite of polyetheretherketone, PEEK, in comparison to a carbon fiber reinforced polysulfone composite. The cell cultures were assessed qualitatively by microscopy and quantitatively using an enzyme assay to determine cytotoxicity. Overall, the cellular response to the PEEK and polysulfone composites were negligible indicating that further in vivo studies with these materials are appropriate.

Antitubulin effects of derivatives of 3-demethylthiocolchicine, methylthio ethers of natural colchicinoids, and thioketones derived from thiocolchicine. Comparison with colchicinoids

Esterification of the phenolic group in 3-demethylthiocolchicine and exchange of the N-acetyl group with other N-acyl groups or a N-carbalkoxy group afforded many compounds which showed superior activity over the parent drug as inhibitors of tubulin polymerization and of the growth of L1210 murine leukemia cells in culture. A comparison of naturally occurring Colchicum alkaloids with thio isosters, obtained by replacing the OMe group at C(10) with a SCH3 group, showed the thio ethers to be invariably more potent in these assays. The comparison included 3-demethylthiodemecolcine prepared from 3-demethylthiocolchicine by partial synthesis. Thiation of thiocolchicine with Lawesson's reagent afforded novel thiotropolones which exhibited high antitubulin activity. Their structures are fully secured by spectral data. Colchicine and several of its analogues show good antitumor effect in mice infected with P388 lymphocytic leukemia, and all of them show high affinity for tubulin and inhibit tubulin polymerization at low concentration. Consequently, antitubulin assays with this class of compounds can serve as valuable prescreens for the initial evaluation of potential antitumor drugs.

The inhibition of human neutrophil elastase and cathepsin G by peptidyl 1,2-dicarbonyl derivatives

Neutrophil elastase and cathepsin G are serine proteases that can damage connective tissue and trigger other pathological reactions. Compounds containing a peptide sequence to impart specificity and bearing an alpha-dicarbonyl unit (alpha-diketone or alpha-keto ester) at the carboxy terminus are potent inhibitors of the neutrophil serine proteases (human neutrophil elastase: R-Val-COCH3, Ki = 0.017 microM; R-Val-COOCH3, Ki = 0.002 microM; human neutrophil cathepsin G: R-Phe-COCH3, Ki = 0.8 microM; R-Phe-COOCH3, Ki = 0.44 microM; R = N-(4-[(4-chlorophenyl)sulfonylaminocarbonyl]phenylcarbonyl)+ ++ValylProlyl).

The synthesis of arginylfluoroalkanes, their inhibition of trypsin and blood-coagulation serine proteinases and their anticoagulant activity

Seven arginylfluoroalkanes ('arginine fluoroalkyl ketones') were synthesized by using a modified Dakin-West procedure. The structure of benzoyl-Arg-CF2CF3 was analysed by 19F-n.m.r. spectroscopy and m.s. and the compound was shown to exist primarily as a hydrate or cyclic carbinolamine. Arginylfluoroalkanes are good inhibitors of blood-coagulation serine proteinases and were found to be slow-binding inhibitors for bovine trypsin with Ki values of 0.2-56 microM. Benzoyl-Arg-CF2CF3 was the best inhibitor for bovine thrombin and human Factor XIa, and inhibited thrombin and Factor XIa competitively with Ki values of 13 microM and 62 microM respectively. The best inhibitor for pig pancreatic kallikrein was p-toluoyl-Arg-CF3, with a Ki value of 35 microM. Benzoyl-Arg-CF3 and benzoyl-Arg-CF2CF3 inhibited human plasma kallikrein competitively, with Ki values of 50 microM. None of the seven arginylfluoroalkanes was a good inhibitor of human factor Xa or of Factor XIIa. The arginylfluoroalkanes were tested in the prothrombin time (PT) and activated partial thromboplastin time (APTT) coagulant assays. Two fluoroketones, benzoyl-Arg-CF2CF3 and 1-naphthoyl-Arg-CF3, had significant anticoagulant activity. Benzoyl-Arg-CF2CF3 was found to prolong the PT 1.8-fold at 120 microM and to prolong the APTT 2.4-fold at 90 microM, whereas 1-naphthoyl-Arg-CF3 only prolonged the APTT 1.7-fold at 100 microM.

Synthesis of peptidyl fluoromethyl ketones and peptidyl alpha-keto esters as inhibitors of porcine pancreatic elastase, human neutrophil elastase, and rat and human neutrophil cathepsin G

Comparison of MeO-Suc-Val-Pro-Phe-CO2Me (29) and MeO-Suc-Ala-Ala-Pro-Phe- CO2Me (25) with their corresponding trifluoromethyl ketones 9a and 9b, respectively, in rat and human neutrophil cathepsin G assays showed the alpha-keto esters to be more potent inhibitors. Likewise, Ac-Pro-Ala-Pro-Ala-CO2Me (21) was more potent than its corresponding trifluoromethyl ketone (9c) in both porcine pancreatic elastase and human neutrophil elastase assays. Within a set of Ala-Ala-Pro-Val-CF3 elastase inhibitors, the carbobenzyloxy (Cbz) N-protecting group conferred greater potency as a P5 site recognition unit for elastase than did dansyl, methoxysuccinyl, or tert-butyloxycarbonyl. Initial inhibition of elastase was greater when trifluoromethyl ketone 9f was added from a stock solution of dimethyl sulfoxide than when it had been buffer-equilibrated prior to assay, which suggests that the nonhydrated ketone is the more effective form of the inhibitor. The most potent elastase inhibitor we report is Na-(Ad-SO2)-N epsilon-(MeO-Suc)Lys-Pro-Val-CF3 (16) which has a Ki of 0.58 nM.

Aflatoxin production in cultures of Aspergillus flavus incubated in atmospheres containing selected cotton leaf-derived volatiles

Aspergillus flavus, in solid culture, was exposed to individual selected, commercially obtained volatile compounds that were similar to volatile cotton leaf-derived components. The radial growth pattern of A. flavus and the production of aflatoxin were determined on these volatile exposed cultures. The most bioactive compounds C6-C9 alkenals, completely inhibited the growth of the fungus. Unexpected results demonstrated that 3-methyl-1-butanol and 3-methyl-2-butanol inhibited A. flavus growth by 20% but increased production of aflatoxin B1 by 1.5 to 2-fold. Other relationships of growth and aflatoxin production resulting from exposure to the bioactive volatiles are discussed.

Effects of selected chemicals on the glutathione status in the male reproductive system of rats

Previous studies have suggested a significant role for reproductive tract glutathione in protecting against chemical-induced germ-cell mutations. Therefore, a number of compounds were tested for their ability to perturb glutathione levels in the testes and epididymides as well as liver following single acute dosages to rats. Phorone (250 mg/kg), isophorone (500 mg/kg), and diethyl maleate (500 mg/kg) significantly reduced glutathione in the liver and in both reproductive organs examined. Methyl iodide (100 mg/kg), trimethyl phosphate (600 mg/kg), naphthalene (500 mg/kg), acetaminophen (1500 mg/kg), and pentachlorophenol (25 mg/kg) affected hepatic and epididymal glutathione, but had little or no effect on testicular levels. The ability of isophorone to enhance the covalent binding of tritiated ethyl methanesulfonate (3H-EMS) to spermatocytes was assessed. Perturbation of reproductive tract glutathione by isophorone treatment significantly enhanced the extent of 3H-EMS-induced binding to sperm heads. The temporal pattern of ethylations in sperm heads was consistent with the stage of sperm development known to be susceptible to ethylations by EMS. Therefore, chemical-induced lowering of glutathione in the male reproductive tract may be a mechanism for potentiation of chemical-induced germ-cell mutations.

gamma-Glutamyltranspeptidase-positive rat hepatocytes are protected from GSH depletion, oxidative stress and reversible alterations of collagen receptors

The aim of this study has been to define cytotoxic mechanisms that may cause clonal expansion in the liver of pre-carcinogenic cells. An in vitro model, which has been described previously, was used. Hepatocytes were isolated from carcinogen-treated rats and a high proportion of the cells were gamma-glutamyltranspeptidase (GGT)-positive. The cells were incubated in suspension and exposed to toxic agents in concentrations that induced a moderate increase in cellular leakage within 3 h. Samples were withdrawn and sampled cells were then allowed to attach to collagen-coated plates. Attached cells were stained and the ratio of GGT-positive/GGT-negative cells (GGT-ratio) was determined. The initial GGT-ratio was 10.4 +/- 4.7% and an increased ratio was taken as a sign of toxicity that resulted in a selection of GGT-positive cells. In a first series of experiments it was shown that hydroquinone and menadione increase the GGT-ratio, while diquat, sodium selenite, diethyl maleate or phorone do not. However, diethyl maleate in combination with diquat increased the GGT-ratio. Hydrogen peroxide (5 mM) increased the GGT-ratio as effectively as hydroquinone (0.3 mM). Lower concentrations of H2O2 (0.05 mM) increased the GGT-ratio in GSH-depleted cells. The changes induced by hydroquinone and H2O2 in low concentration were reversible. In another series of experiments, plates coated with antibodies against beta 1-integrin were used. An increase in the GGT-ratio was obtained with anti beta 1-integrin, but not with broad spectrum anti-rat hepatocyte or anti-rat beta 2-microglobulin antibodies as substrata. These data suggested an involvement of the beta 1-integrin in the selection. Taken together, these data indicate that GGT-positive hepatocytes are protected against GSH depletion and oxidative stress that may result in reversible receptor alterations.

Prostaglandin D2 modulates human neutrophil intracellular calcium flux and inhibits superoxide release via its ring carbonyl

We compared the effects of prostaglandin D2 (PGD2), prostaglandin F2 alpha (PGF2) and various ketones on superoxide (OX) release by human neutrophils, which had been stimulated by N-formyl methionyl leucyl phenylalanine (FMLP). Our data suggested that the ring carbonyl of PGD2 is essential to its inhibitory effect on OX release, but the carbonyl group as a ketone, alone is not sufficient. Using the fluorescent Ca2+ probe, Fura-2AM, we found that PGD2 increased the rate of decline of FMLP stimulated intracellular free Ca2+ (Ca)i, but that PGF2 had no effect. cAMP altered FMLP stimulated (Ca)i, in a pattern similar to PGD2. Furthermore, the ring carbonyl of PGD2 is crucial to its effect on OX as well as on (Ca)i.

No influence of enzyme inhibitors on the hydroxylation of methotrexate in rats

In anaesthetized rats 50% of an infused dose of methotrexate (MTX) was excreted into the bile. About 3% was metabolized to 7-hydroxymethotrexate (7-OH-MTX), which appeared also in the bile. Pretreatment with allopurinol had no influence on the elimination of MTX or the production of 7-OH-MTX during a 3-h infusion of MTX. Cyanamide decreased the total MTX clearance, but increased the biliary elimination of 7-OH-MTX. Phorone decreased the biliary MTX-clearance, but not the biliary secretion of 7-OH-MTX. The results show that neither aldehyde oxidase nor xanthine oxidase is the predominant hydroxylating enzyme for MTX in the rat.

Inhibition by diacylmethane derivatives of mutagenicity and nucleic acid binding of 2-aminofluorene derivatives

The active methylene compounds acetylacetone, 1,1,1-trifluoroacetylacetone, benzoylacetone, dibenzoylmethane, and 1,3-indandione inhibited the mutagenicity of 2-nitrofluorene in Salmonella typhimurium. They also inhibited the N,O-acetyltransferase-catalyzed transfer RNA binding of N-hydroxy-2-acetylaminofluorene, but they did not inhibit N,O-acetyltransferase. However, only 1,3-indandione and 1,1,1-trifluoroacetylacetone significantly inhibited the binding of N-acetoxy-2-acetylaminofluorene to transfer RNA. Reaction of the trifluoro compound with the acetoxy compound yielded 1-(N-2-fluorenylacetamido)acetone. These results demonstrate that active methylene compounds can inhibit mutagenicity and nucleic acid binding of chemical carcinogens.

Inhibition of rat liver and duodenum soluble catechol-O-methyltransferase by a tight-binding inhibitor OR-462

The inhibition kinetics of rat liver and duodenum soluble catechol-O-methyltransferase (COMT) with a disubstituted catechol OR-462 was studied. After preincubation of the enzyme and inhibitor in the presence of magnesium and S-adenyosylmethionine, an inhibition about thirty times greater than that without preincubation was observed. Reversible tight-binding inhibition was demonstrated with Ki values of 0.7 nM and 1.0 nM for liver and duodenum enzyme, respectively. Km values of 53.4 microM and 56.9 microM for substrate 3,4-dihydroxybenzoic acid and 23.0 microM and 17.5 microM for S-adenosylmethionine were calculated for liver and duodenum enzyme, respectively. A catalytic number of 24/min for liver soluble COMT was calculated.

Inhibition kinetics of acetylcholinesterase with fluoromethyl ketones

A series of trifluoromethyl ketones that reversibly inhibit acetylcholinesterase and pseudocholinesterase were synthesized. By analogy to chymotrypsin and on the basis of data reported here, we propose that the active-site serine adds to the ketone to form an ionized hemiketal. The compound (5,5,5-trifluoro-4-oxopentyl)trimethylammonium bicarbonate (1) inhibits acetylcholinesterase with Ki = 0.06 X 10(-9)M and pseudocholinesterase with Ki = 70 X 10(-9)M. Replacement of the nitrogen of 1 by carbon (compound 2) increases Ki for 1 200-fold for acetylcholinesterase but does not significantly alter Ki for pseudocholinesterase. The Ki for the methyl ketone corresponding to 2 is 2 X 10(-4)M for both enzymes, as compared with 12 X 10(-9)M for the trifluoromethyl ketone (acetylcholinesterase). For both enzymes, a linear decrease in log Ki with decreasing pK of the inhibitor hydrate was observed with ketones containing from 0 to 3 fluorines. We attribute this effect to the stabilization of the hemiketal oxyanion. The reduction of the pK of the hemiketal by the trifluoromethyl group is an important contributing factor to the low Ki of trifluoromethyl ketones. The inhibition of acetylcholinesterase by tetramethylammonium chloride and trifluoroacetone was compared to the inhibition by 1, which is a composite of the two smaller inhibitors. The entropic advantage of combining the smaller inhibitors into one molecule is 1.1 X 10(3)M. Inhibitors with Ki less than or equal to 70 X 10(-9) M are slow binding (Morrison, 1982; Morrison & Walsh, 1988). The kinetic data do not require formation of a noncovalent complex prior to formation of the ketal, although such a complex(es) cannot be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of the glutathione-depleting agents diethylmaleate, phorone and buthionine sulfoximine on biliary copper excretion in rats

The involvement of glutathione (GSH) in the biliary excretion of Cu was investigated in bile-cannulated inbred WAG/Rij and BN rats, pretreated with diethylmaleate (DEM), phorone or buthionine sulfoximine (BSO) and injected with Cu doses of 10 or 30 micrograms/100 g body wt. DEM reduced liver GSH to 27-56% and biliary GSH excretion to 18-38%; phorone reduced GSH in the liver to 55% and increased it in the bile (113%) followed by a slight decrease (79%); BSO reduced liver GSH to 50% and bile GSH to 20%. After injection of Cu to control rats a profile of biliary Cu excretion was found, composed of a slowly (SCuE) and a rapidly (RCuE) disappearing component, the latter only present after the dose of 30 micrograms Cu. DEM had no effect on SCuE after a 10 micrograms dose and a temporary effect on SCuE after a 30 micrograms dose in both WAG/Rij and BN rats. Phorone reduced SCuE after both Cu doses to 50%. Both agents abolished RCuE and reduced endogenous biliary Cu excretion to less than 50%. Release of injected Cu from plasma and uptake by the liver was inhibited by DEM and phorone in both rat strains; in BN rats basal plasma Cu level of DEM-treated rats was increased as well. BSO reduced SCuE after both Cu doses but had no influence on RCuE. Endogenous Cu excretion was reduced by BSO in BN rats but not in WAG/Rij rats. The results show that biliary Cu excretion proceeds by a pattern, the components of which can be affected differently by the various drugs. They also indicate that GSH is not directly involved in biliary Cu excretion but suggest that it may play a role in the metabolism of Cu in the liver.

Effects of acetone and methyl n-butyl ketone on hepatic mixed-function oxidase

The administration of ketones potentiates CCl4 hepatotoxicity; however, the potencies of the ketones differ. The aim of the present study was to assess potential differences between acetone and methyl n-butyl ketone (MnBK) on cytochrome P-450. The effects of single and repetitive doses of acetone and MnBK were determined in male rats by estimating the rate of metabolite formation of three substrates and the hepatic content of cytochrome P-450. A single treatment with acetone (13.5 mmol/kg or greater) enhanced the oxidation of aniline and 7-ethoxycoumarin, whereas repetitive treatments also increased aminopyrine demethylation and cytochrome P-450 content. Single and repetitive treatments of MnBK (15 mmol/kg) augmented the oxidation of all three substrates and increased cytochrome P-450 content. The effects of the ketones on cytochrome P-450 isozymes were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Acetone and MnBK increased the 52.1 and 54.1 kD forms and, in addition, MnBK tended to increase the 50.6 kD species. The data indicate that ketones differ in the type of isozymes induced and in the degree of induction. The higher potency of MnBK, compared to acetone, is probably associated with the fact that MnBK affects a greater number of isozymes than acetone.

Synthesis and antiviral activity of thiosemicarbazone derivatives of pyridazinecarbaldehydes and alkyl pyridazinyl ketones

Various novel thiosemicarbazones (TSCs) 15b-e, 16b-e, 17b-e, 18b-e, and 19b-e derived from 4-pyridazinecarbaldehyde, 3-pyridazinecarbaldehyde, 4-acetylpyridazine, 3-acetylpyridazine, and 3-propionylpyridazine were prepared and their cytotoxic and antiherpetic potentials were evaluated. It was found that the replacement of the 2-pyridylmoiety in aldehyde derived compounds 20a-c by a 4-pyridazinyl group (compounds 15b-d) abolishes biological activity. However, in TSCs derived from 3-pyridazinecarbaldehyde (16b-d) the cytotoxic potency was considerably reduced (factor approximately 300), while the antiviral activity was largely retained. A total loss of biological activity occurred when the pyridyl group in TSC 20d, derived from 2-acetylpyridine, was replaced by the 4-pyridazinyl system (17d). By employment of the 3-pyridazinyl unit for isosteric modification, however, the cell toxicity could be reduced significantly (factor 100) without impairing the antiherpetic potential also in the series of TSCs derived from N-heteroaromatic ketones. It was observed that there is no obvious influence of the size of the cycloamino substituent on the biological activities in compounds 20a-d, 15b-d, 16b-d, 17b-d, and 18b-d. While the pyridine derived TSCs in our experiments proved clearly cytotoxic at lower concentrations than those being antivirally active, the aza-analogous compounds derived from 3-acetylpyridazine (18b-e) inhibited plaque formation at concentrations equal to those causing cytotoxic effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetone compared to other ketones in modifying the hepatotoxicity of inhaled 1,2-dichlorobenzene in rats and mice

The ability of acetone and 3 other ketone vapours to influence the hepatotoxicity of inhaled 1,2-dichlorobenzene (DCB) was examined in rats and mice. Methylethylketone, methylisobutylketone or cyclohexanone increased liver cytochrome P-450 content and glutathione-S-transferase (GST) activity, but did not affect serum glutamate dehydrogenase (GLDH) activity in rats. Pre-exposure to these ketones enhanced DCB-induced increase in serum GLDH activity (8-63-fold), while the increases in cytochrome P-450 content (33-86%) and GST activity (42-64%) were identical to those resulting from exposure to ketones alone. Each of the 3 levels of exposure to acetone elicited cytochrome P-450 and GST responses comparable with those caused by the other ketones. In spite of that, acetone pre-exposure potentiated (4785 ppm), reduced (10670 ppm) or suppressed (14790 ppm) DCB-induced liver toxicity. In mice, the 3 ketones mentioned above interacted with DCB on centrolobular liver glucose-6-phosphatase (G-6-Pase) while acetone pre-exposure elicited an interactive G-6-Pase response in the mediolobular area alone, suggesting topographic change.

Brain glutathione and the anti-hypoxic effect of glutathione depletors in mice

The anti-hypoxic effect (assessed by a standard hypoxia survival test) 3 hr after 2-cyclohexene-1-one (CHX) was completely abolished by injections of L-cysteine after CHX. Under these conditions, brain GSH was depleted to about 50% of the control level in CHX-treated mice and recovered to about 80% of control level following L-cysteine post-treatment. However, D-cysteine could not cause such effects. Intracerebroventricular injection of CHX, which caused a selective depletion of brain GSH, produced an anti-hypoxic effect. Thus, the anti-hypoxic effect may be related to the decrease of brain GSH levels.

2,5-Hexanedione modifies skeletal proteins of the red blood cells and increases the binding of hemoglobin to the membrane

The effects of 2,5-hexanedione (2,5 HD) on skeletal proteins of red blood cells (RBCs) were investigated both in vitro (human RBCs) and in vivo in male Sprague-Dawley rats which had been treated with the drug for several days. We found that 2,5 HD induced the following major changes in the electrophoretic pattern of the skeletal proteins: (i) the appearance of high-molecular weight bands, (ii) a dose-dependent decrease in spectrin Bands 1 and 2, and (iii) a dose-dependent increase in the amount of hemoglobin (Hb) associated with the membrane. Membranoskeletons, prepared from resealed ghosts which had been previously treated with 2,5 HD, were able to bind an increased amount of Hb from untreated RBCs, thus suggesting a drug-induced modification of the membrane. Extraction of spectrin and actin from ghosts did not remove the membrane-bound Hb and, furthermore, Hb bound to 2,5 HD-treated membranes mainly bearing Band 3 and free of peripheral proteins. These data suggested a 2,5 HD-induced modification of an intrinsic membrane protein, probably Band 3. This hypothesis was consistent with the observation that 2,5 HD also induced a modification of Band 3 aminogroups, as evidenced by a dose-dependent decrease in the binding of eosin probes. Furthermore, RBCs treated in vitro with 2,5 HD bound an increased amount of autologous immunoglobulins (IgG). As reported by Kay and Low et al. the binding of autologous IgG is a phenomenon associated with the aging process of RBCs and may involve a modification of Band 3. Our data show that RBCs treated with 2,5 HD acquired various characteristics of senescent cells such as spectrin cross-linking, Hb-membrane binding and increased IgG binding, and suggest that 2,5 HD treatment might affect RBC survival.

Effect of some 4-alkyl-5-dimethylamino-1-phenyl-1-penten-3-one hydrochlorides and related compounds on respiration in mouse liver mitochondria

5-Dimethylamino-1-phenyl-1-penten-3-one hydrochloride (1a) has high inhibiting properties in mitochondria isolated from mice liver. Substitution at the 4-methylene group of 1a by different alkyl substituents lead to compounds with wide variation in respiration-inhibiting properties. No correlations were found between either the Charton steric parameter (v), Taft inductive value (f*) or fragmental constant (f) of the substituents at position 4 of the Mannich bases with inhibition of respiration. However the biological results suggested two receptor sites were present in the mitochondria which may interact with the Mannich bases namely a common receptor for all compounds and in addition a narrow hydrophobic binding area which can accommodate a n-butyl or higher alkyl groups which are present in some of the compounds.

Eclipse products of poliovirus after cold-synchronized infection of HeLa cells

The particles derived from radioactively labeled poliovirus, in cold-synchronized infection of HeLa cells, were studied. After temperatures shift-up, radioactivity was transferred rapidly from the infecting virions (160 S) to 135 S, and from there more slowly to 110 S, a previously unreported eclipse product. Both the 135 and 110 S particles contained RNA, lacked VP4, and were H-antigenic. In the 135 S particles, part of the VP1 complement was lost; in addition to this, the VP2 polypeptide of the 110 S particles was cleaved in situ. The formation of eclipse products was insensitive to cycloheximide. Arildone totally blocked the formation of 135 S particles, but not their further processing.