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PubMed2004

3,6-Dihydroxy-2-(11-phenylundecanoyl)cyclohex-2-en-1-one from Virola venosa bark.

The structure of the title compound, C23H32O4, an arylalkanone isolated from the petroleum ether fraction of the ethanol extract of the bark of Virola venosa, has been established by NMR spectroscopy and, for the first time, by X-ray structure analysis. Two independent molecules of the same enantiomer are present in the unit cell. Both molecules exhibit an intramolecular hydrogen bond, which can be correlated with a rare signal observed at 18.28 p.p.m. in the 1H NMR spectrum. The packing, in space group P1, is determined by a pseudo-center of symmetry leading to a short intermolecular contact, which is present in one molecule but does not occur in the other. As a consequence, the O-C-C-O torsion angles [-16.9 (3) and -12.7 (3) degrees ] through the ketone and its adjacent hydroxy group are significantly different in the two molecules.

Alkanes↗
PubMed1991

Structure of (+/-)-(2S,1'S)-2-[hydroxy(phenyl)methyl]-2-methylcyclohexanone, C14H1802.

Mr = 281.30, monoclinic, P2(1)/n, a = 10.966 (4), b = 7.170 (3), c = 15.976 (4) A, beta = 93.14 (2) degrees, V = 1254.3 (9) A3, Z = 4, Dx = 1.16 g cm-3, lambda (Mo K alpha) = 0.71069 A, mu = 0.706 cm-1, F(000) = 472, T = 295 K, final R = 0.057 for 1212 unique observed reflections. The compound was prepared by reaction of the trichlorotitanium-delta 1(2)-enolate of 2-methylcyclohexanone with benzaldehyde.

Cyclohexanones↗
PubMed1976

In vitro studies on the mechanism of acquired resistance to tuberculous infection. I. The relationship between lymphocytes and macrophages in cellular immunity to tuberculous infection.

The relationship between lymphocytes and macrophages in cellular immunity against tuberculous infection was studied by means of an in vitro cell culture system without addition of streptomycin. The peritoneal macrophages were obtained from normal mice or mice immunized with heat-killed tubercle bacilli in paraffin oil, boosted with live BCG and infected with H37Rv cells in vitro. The infected monolayers of macrophages were cultivated for 48 hr with immune lymphoid cells obtained from immunized mice. The intracellular growth of H37Rv cells 3,5 and 7 days after infection was examined by counting tubercle bacilli within infected macrophages under a microscope. 1) The increase of bacilli within macrophages derived from immunized mice was slightly smaller than that in normal macrophages. 2) The addition of immune lymph node cells to the macrophage monolayers resulted in a marked decrease in the number of bacilli within both normal and "immune" macrophages. Conversely, normal lymph node cells exhibited an enhancing effect on the intracellular bacillary growth. 3) Immune lymph node cells showed a higher capacity to cause macrophages to suppress intracellular growth of bacilli than that of splenic lymphoid cells or thyrmocytes after addition to macrophage monolayers. 4) The treatment of lymphoid cells with inhibitors of protein synthesis, cycloheximide or streptovitacin A, resulted in a remarkable reduction of the ability of sensitized lymphocytes to cause macrophages to suppress multiplication of intracellular bacilli.

Animals↗
PubMed2006

Inhibition of tumor growth by NF-kappaB inhibitors.

NF-kappaB is a transcription factor that induces inflammatory cytokines and anti-apoptotic proteins. NF-kappaB is often constitutively activated in human cancers and leukemias, which might increase the malignant character of neoplastic diseases. Therefore, NF-kappaB inhibitors might be useful as anticancer agents. Our research team designed a new NF-kappaB inhibitor that is based on the structure of the antibiotic epoxyquomicin C isolated from a microorganism. The designed compound, DHMEQ, inhibited the ligand-induced activation of NF-kappaB, and it also inhibited the constitutively activated NF-kappaB in cancer cells. DHMEQ is a unique inhibitor of NF-kappaB that acts at the level of the nuclear translocation. It inhibited both canonical and non-canonical NF-kappaB activating pathways. It inhibited various carcinomas and leukemias in animal models without any toxicity, and might be useful as an anticancer agent.

Animals↗
PubMed1992

Plasma triglyceride and low density lipoprotein metabolism.

This study examines the relationship between plasma triglyceride and low density lipoprotein (LDL) levels by measuring the turnover of the native and 1,2 cyclohexanedione-treated lipoprotein in 25 healthy adults. Plasma triglyceride showed a strong positive correlation with circulating LDL apoprotein (apo LDL) mass. In order to achieve a satisfactory fit to the kinetic data it was necessary to postulate the existence of two plasma apo LDL pools (A and B). When subjects were grouped in quintiles on the basis of circulating apo LDL mass, pool A predominated in those in the lowest quintile. The fractional catabolic rate (FCR) of apo LDL from this pool was high (FCR = 0.57 +/- 0.06 pools day-1). As plasma triglyceride and apo LDL mass rose, apoprotein accumulated in the more slowly metabolized pool B as a result of an increase in the rate of input of apo LDL into the latter. The fractional clearance rate of protein from this pool remained unchanged at 0.26 +/- 0.04 pools day-1. Synthesis of apo LDL into pool B correlated with plasma triglyceride (r = 0.553, P less than 0.01), suggesting that the protein in this pool was derived from large, triglyceride-rich very low density lipoprotein.

Adult↗
PubMed1992

Factors affecting antibacterial activity of hop compounds and their derivatives.

The antibacterial effect of weak acids derived from the hop plant (Humulus lupulus L.) increased with decreasing pH. Analysis of the minimum inhibitory concentration of such compounds against Lactobacillus brevis IFO 3960 over pH 4-7 suggests that undissociated molecules were mainly responsible for inhibition of bacterial growth. The antibacterial activity of trans-isohumulone was ca 20 times greater than that of humulone, 11 times greater than that of colupulone and nine times greater than that of trans-humulinic acid when the degree of ionization was taken into account. Monovalent cations (K+, Na+, NH4+, Rb+, Li+) stimulated antibacterial activity of trans-isohumulone but the effect was smaller than that observed with H+. The response to divalent cations varied: Ca2+ had little effect on antibacterial activity, whereas Mg2+ reduced activity. Lipid materials and beta-cyclodextrin also antagonized the antibacterial action of trans-isohumulone.

Anti-Bacterial Agents↗
PubMed1983

Modification of arginines in bovine growth hormone.

Treatment of bovine growth hormone with 1,2-cyclohexanedione - in borate buffer - selectively modified 11.8 out of the 13 arginines in the molecule. Kinetic analysis of the data showed a good fit to a pseudo first-order curve, with an apparent velocity constant k: 2 X 10(-2) min-1. The modification brought about a complete loss of bovine growth hormone capacity to compete with 125I-labelled hormone for rat liver binding sites. Circular dichroism studies indicated no apparent changes in protein conformation in the modified hormone. Full binding capacity was restored upon regeneration of arginines by hydroxylamine treatment. These results suggest that one or more arginines are involved in the binding of bovine growth hormone to its specific receptors. The non-reactive arginine was identified as arginine 181.

Amino Acids↗
PubMed1988

On the receptor binding site of relaxins.

Relaxin plays a critical role in viviparity and has recently been implicated as a hormone of oviparity as well. In most mammals relaxin causes the widening of the birth canal during parturition and suppresses uterine motility during pregnancy. Relaxins isolated from several species have shown a great deal of sequence variability, and speculations regarding a putative receptor interaction site have, as a consequence, varied considerably. The isolation of skate relaxin in combination with our chemical modification data enable us to suggest a unique site for the interaction of relaxin with its uterine and symphyseal receptors.

Amino Acid Sequence↗
PubMed1990

Formation of optically pure N-acyl-N,N'-dicyclohexylurea in N,N'-dicyclohexylcarbodiimide-mediated peptide synthesis.

N-acylurea, a side product in peptide synthesis from DCC, preserves its chiral integrity although peptides formed simultaneously in the same reaction are racemized to a large extent. This observation is inconsistent with the generally accepted opinion that racemization-prone O-acylisourea is a common intermediate for both peptides and N-acylurea. Chiral purity of N-acylureas and peptides was determined by HPLC using chiral stationary phases. An efficient method of synthesis of chirally pure N-acylureas is also presented.

Amino Acids↗
PubMed1994

Modification of arginine residues in ovine prolactin by 1,2-cyclohexanedione. Effect on binding capacity to lactogenic receptors.

The reactivity of arginine residues in ovine prolactin was studied by reaction with 1,2-cyclohexanedione. Kinetic analysis of the data showed a good fit with two simultaneous pseudo-first-order equations with apparent velocity constants of 0.28 and 1.2 x 10(-2) min-1, corresponding to 1.8 'fast' and 8.7 'slow' residues, respectively. Modification led to a decrease in binding capacity to lactogenic rat liver receptors, and apparently the modification of the two 'fast' reacting arginine residues is responsible for the rapid loss of this capacity. The presence of a non-reacting arginine has been described in human and bovine growth hormones, and it is located near the carboxy-terminus. This lack of reactivity is probably due to the formation of a salt bridge, since the arginine residue becomes susceptible to modification once the peptide is separated from the rest of the molecule. This salt bridge is absent in ovine prolactin, since the homologous arginine residue is reactive with cyclohexanedione. This result suggests that there could be a difference between the three-dimensional structure of ovine prolactin and of the growth hormones, at least near the carboxy-terminal region of the molecule.

Amino Acid Sequence↗
PubMed1978

Decreased heparin sensitivity of cycholhexanedione-modified thrombin.

Modification of 5--6 arginine residues of thrombin with 1,2-cyclohexanedione has resulted in the selective abolition of the heparin sensitivity of the enzyme's reaction with antithrombin-III, whereas the antithrombin-III sensitivity of native and modified thrombin was indistinguishable. It is suggested that heparin accelerates the thrombin antithrombin-III reaction by interacting with thrombin.

Animals↗
PubMed1979

Identification of the C-1-phosphate-binding arginine residue of rabbit-muscle aldolase. Isolation of 1,2-cyclohexanedione-labeled peptide by chemisorption chromatography.

The arginine-specific reagent 1,2-cyclohexanedione reacts selectively with the arginine residue of the C-1-phosphate-binding site of aldolase and inactivates the enzyme. The labeled peptide isolated from tryptic digests of inactivated aldolase was found to correspond to the sequence Leu-43 to Arg-56, the residue modified by cyclohexanedione being Arg-55. This peptide was absent form digests of aldolase treated in the same way but protected from inactivation by the presence of substrate, thus correlating modification of Arg-55 with loss of activity. Selective isolation ofthe peptide containing the modified arginine residue was effected by chemisorption chromatography on boric acid gel, a procedure exploiting the specific interaction of matrix-bound boric acid groups with vicinal cis-hxdroxyl groups of cyclohexanedione-modified arginine side chains.

Animals↗
PubMed1981

Modification of arginine residues in porcine pancreatic phospholipase A2.

Although phenylglyoxal monohydrate reacts with Arg-6 in porcine pancreatic phospholipase A2, concomittantly the alpha-amino group of the N-terminal Ala-1 residue is quantitatively transaminated. Due to this latter reaction the enzymatic activity toward micellar substrate is lost irrespective of the Arg-6 modification. Upon reaction of [7-(14)C]phenylglyoxal monohydrate with alpha-amino-blocked phospholipase A2 analogs, two molecules of the reagent were incorporated per protein molecule, which were found to be present on Arg-6. Removal of alpha-amino-blocking groups after the modification reaction furnished the corresponding Arg-6-modified phospholipases possessing 30-38% of their original specific enzymatic activities in the egg-yolk assay. After reaction of 1,2-[1-(14)C]cyclohexanedione with porcine phospholipase A2 the crude reaction mixture was purified by chromatography on quaternary diethyl-(2-hydroxypropyl)aminoethyl-Sephadex in the presence of borate. A fraction was obtained containing a pure protein in which one molecule of 14C-labeled reagent per protein molecule was incorporated which was found to be localized almost exclusively on Arg-6. Cyclohexanedione modification of Arg-6 in phospholipase A2 does not significantly influence its catalytic activity when assayed toward monomeric and micellar substrates. The results of direct binding experiments using substrate analogs and of monolayer studies of the phospholipase modified at Arg-6 by cyclohexanedione are in agreement with previous findings that Arg-6 is involved in the interaction of the enzyme with lipid-water interfaces.

Aldehydes↗
PubMed1981

On the mode of action of the immunosuppressive sesquiterpene ovalicin.

When the potent immunosuppressive sesquiterpene ovalicin is added to lymphocyte cultures one first observes a preferential inhibition of uridine incorporation into rRNA. The uptake of the nucleoside, its conversion into the triphosphate or the polymerizing activity itself are not affected. A longer period of incubation with the drug results in a marked decrease in the number of ribosomes, with a concomitant reduction of the rate of leucine incorporation into all cellular proteins. After extended periods of time, the incorporation of thymidine into DNA in stimulated lymphocytes as well as in SV49.1 lymphoma cells is inhibited by 1 nM ovalicin or less, although part of the incorporation seems to be resistant to the drug even at much higher concentrations. A similar affect is observed with 3T6 mouse fibroblasts or HeLa cells. Here, however, a much longer incubation with the drug is required. This observation explains the selective effect of ovalicin on lymphocytes observed in vivo.

Animals↗
PubMed1981

Reactivity of D-amino acid oxidase with 1,2-cyclohexanedione: evidence for one arginine in the substrate-binding site.

D-Amino acid oxidase is inactivated by reaction with 1,2-cyclohexanedione in borate buffer at pH 8.8. The reaction follows pseudo-first-order kinetics. The present of benzoate, a substrate-competitive inhibitor of the enzyme, protects substantially against inactivation. Partial reactivation could be obtained by removal of borate and its substitution with phosphate buffer. The reaction of 1,2-cyclohexanedione with the enzyme at different inhibitor concentrations appears to follow a saturation kinetics, indicating the formation of an intermediate complex between enzyme and inhibitor prior to the inactivation process. The partially inactivated enzyme shows the same apparent Km but a decreased V as compared to the native D-amino acid oxidase. Similarly, the inhibited enzyme fails to bind benzoate. Amino acid analysis of the 1,2-cyclohexanedione-treated enzyme at various times of inactivation shows no loss of amino acid residues except for arginines. Analysis of the reaction data by statistical methods indicates that three arginine residues react with the inhibitor at slightly different rates, and that one of them is essential for catalytic activity. The presence of benzoate, while it prevents the loss of activity, reduces by one the number of arginine residues hit by the reagent in the reaction of 1,2-cyclohexanedione with D-amino acid oxidase.

Animals↗
PubMed1982

Chemical modification studies on Ricinus communis (Castor Bean) agglutinin.

Ricinus communis agglutinin was subjected to various chemical treatments and the effect on its hemagglutinating and saccharide-binding properties was studied. Acetylation, succinylation and citraconylation led to a complete loss in the activity of the agglutinin, whereas reductive methylation had no effect on the activity, showing that charged amino groups were involved in the hemagglutinating and saccharide-binding activity of Ricinus agglutinin. Modification of tryptophyl, arginyl and carboxyl-group-containing residues did not lead to any loss in the activity of the agglutinin. Acetylation of tyrosyl groups with N-acetylimidazole strongly reduced the hemagglutinating and saccharide-binding property of Ricinus agglutinin. The loss in activity was restored on deacetylation of the tyrosyl groups. Modification of tyrosyl residues also led to a change in the immunological properties of the agglutinin. The initial rate of modification of tyrosyl and amino groups and the concomitant loss of activity was reduced in the presence of lactose.

2-Hydroxy-5-nitrobenzyl Bromide↗
PubMed1993

Formation of diacylglycerol, inositol phosphates, arachidonic acid and its metabolites in macrophages.

Treatment of macrophages with zymosan, 4 beta-phorbol 12-myristate 13-acetate (PMA) and fluoride but not with A 23187 or arachidonic acid (delta Ach) leads to a generation of diacylglycerol (acyl2Gro). Formation of inositol phosphates is achieved with zymosan, only. An elevation of intracellular calcium is obtained with zymosan and A 23187 but not with PMA, fluoride or delta Ach. Prior treatment of the cells with phorbol ester for 3 h which has been shown recently to result in a down-regulation of protein kinase (PK) C-beta but not PKC-delta [Duyster, J., Schwende, H., Fitzke, E., Hidaka H. & Dieter P. (1993) Biochem. J. 292, 203-207] has no effect on the zymosan-induced formation of acyl2Gro or inositol phosphates but inhibits the PMA-induced generation of acyl2Gro. Down-regulation of PKC-delta by prior phorbol ester treatment for 24 h augments the zymosan-induced generation of acyl2Gro and inositol phosphates. The acyl2Gro lipase inhibitor RG 80267 inhibits the PMA-induced and fluoride-induced generation of prostaglandin (PG) E2, reduces the zymosan-induced release of PGE2 by 50% but has no effect on PGE2 formation of unstimulated, A 23187-treated or delta Ach-treated cells. Furthermore, RG 80267 enhances accumulation of delta Ach-labeled acyl2Gro in response to zymosan, PMA and fluoride. These data indicate that zymosan activates a phosphatidylinositol 4,5-bisphosphate-specific phospholipase (PL) C, that generation of acyl2Gro by PMA and fluoride occurs via hydrolysis of other phospholipids, that PKC-beta is involved in the PMA-induced generation of acyl2Gro and PKC-delta negatively modulates the zymosan-induced activation of PLC and PMA and fluoride induce a liberation of delta Ach from acyl2Gro, A 23187 activates the PLA2 pathway and zymosan stimulates both, the acyl2Gro- and PLA2-pathway.

Animals↗