Stereoselective hydrolysis of cis- and trans-stilbene oxides by hepatic microsomal epoxide hydrolase.
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We investigated the capacity of DIDS to influence degranulation and superoxide anion (O-2) generation by human neutrophils exposed to soluble, surface-active stimuli. DIDS caused a concentration-related (25-200 microM) inhibition of myeloperoxidase (MPO) release from N-formyl-methionyl-leucyl-phenylalanine (FMLP), 5(S), 12(R)-dihydroxy-6, 14-cis-8, 10-trans-eicosatetraenoic acid (LTB4), 1-0-hexadecyl/octadecyl-2-0-acetyl-sn-glyceryl-3-phosphorylcholine (AGEPC) and phorbol myristate acetate (PMA)-stimulated neutrophils. In contrast, DIDS had no effect on O-2 production by FMLP and PMA activated cells, whereas it enhanced LTB4 and AGEPC-elicited O-2 generation. The respective effects of DIDS on these neutrophil activities were reversed by washing the cells prior to exposure to stimulus. Thus, DIDS represents a useful pharmacologic probe for investigating the role(s) of anions in the mechanisms of neutrophil activation with structurally and chemically dissimilar stimuli.
In the present study, we investigated the effect of DIDS on Na+ regulation of alpha 2-adrenoreceptors in human platelets. Pretreatment of platelet membranes at 23 degrees C for 60 min with DIDS produced a reduction in the affinity of the receptors for both antagonist and agonist in a concentration related manner; however, there was a marked difference in the degree of reduction in the affinity of the receptors for antagonist and agonist. Thus, at 1 mM concentration of DIDS, the affinity of the receptors for antagonist was reduced by 2-fold while the affinity of the receptors for agonist was reduced by 14-fold. Furthermore, this concentration of DIDS abolished the ability of Na+ in reducing the affinity of the receptors for agonist. We suggest that the effect of DIDS is via Na+ binding component of the alpha 2-adrenoreceptor-adenylate cyclase complex.
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The effects of pinosylvin, pinosylvin monomethyl ether, pinosylvin dimethyl ether, and resveratrol on the fungal shoot blight and canker pathogen of conifers Sphaeropsis sapinea were examined in vitro. Effects of compounds, isolates, and concentrations on both conidial germination and mycelial growth were significant (values of P < 0.001), indicating inhibitory activity of these compounds.
The methanol extract from the bark of Yucca periculosa F. Baker afforded 4,4'-dihydroxstilbene, resveratrol and 3,3',5,5'-tetrahydroxy-4-methoxystilbene and had growth regulatory activity against the Fall Army worm (Spodoptera frugiperda J.E. Smith, Lepidoptera:Noctuidae) an insect pest of corn. The most active compound was 3,3',5,5'-tetrahydroxy-4-methoxystilbene which had significant effects at 3 microg/g in diets. In addition to the inhibitory activity on bleaching of crocin induced by alkoxyl radicals, these compounds also demonstrated scavenging properties toward 2,2-diphenyl-1-picrylhydrazyl in TLC autographic and spectrophotometric assays. Our results indicate that these compounds could be involved in interference of sclerotization and moulting. These compounds appear to have selective effects on the pre-emergence metabolism of the insect. The results were fully comparable to known natural insect growth inhibitors such as gedunin and Cedrela extracts and have had a possible role as natural insecticidal agents.
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The anti-HIV sulfonated dye, resobene, was found to be a potent inhibitor of the attachment of HIV to target cells, the fusion of envelope- and CD4-expressing cells, and the cell-to-cell transmission of virus. Resobene inhibited the infection of phenotypically distinct, established human cell lines and fresh human peripheral blood lymphocytes and macrophages by laboratory-derived isolates of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), and a panel of biologically diverse primary clinical isolates, including syncytium-inducing and non-syncytium-inducing viruses and strains representative of the various virus clades found worldwide. The compound was also active against all drug-resistant virus isolates tested. Cell-based and biochemical mechanism of action studies demonstrated that the compound inhibits the attachment of infectious virus and fusion of virus-infected cells to uninfected target cells by binding to the cationic V3 loop of the envelope glycoprotein. Resobene effectively inhibited the infection of cell populations which do and do not express cell surface CD4. Resobene prevented infection of the cervical epithelial cell line ME180, suggesting the compound may effectively act as a topical microbicide to prevent the sexual transmission of HIV.
Several iron complexes [FeII(PA)2 (PA = picolinate), FeII(bpy)2(2+), FeII(OPPh3)4(2+), FeII(MeCN)4(2+), (Cl8TPP)FeII(py)2 (Cl8TPP = tetrakis(2,6-dichlorophenyl)porphyrin), and FeIIICl3] in combination with R'OOH (R' = H, t-Bu) catalytically activate O2 to oxygenate hydrocarbons [e.g., c-C6H12-->c-C6H10(O) [9 O2 turnovers per FeII(PA)2 or FeII(bpy)2(2+), and 13 per (Cl8TPP)-FeII(py)2]; PhCH2CH3-->PhC(O)CH3 (up to 25 O2 turnovers per FeIILx); c-C6H10-->c-C6H8(O) (up to 9 O2 turnovers per FeIILx); PhCH(Me)2-->PhC(O)Me, Ph(Me)2COH, and Ph(Me)C = CH2 (up to 5 O2 turnovers per FeIILx); and cis-PhCH = CHPh-->2PhCH(O) (up to 2 O2 turnovers per FeLx)]. With large R'OOH/FeLx ratios spontaneous decomposition occurs to give free O2 that is incorporated into the substrates. The product profiles for the various FeIILx/R'OOH, O2/RH systems and their electrochemical characterization during steady-state turnover confirm that the first-formed intermediate is a one-to-one R'OOH/FeIILx adduct (e.g., [(PA)2-FeIIOOR' + pyH+] (1)) (Fenton reagent), which reacts with (a) excess FeII(PA)2 to give (PA)2FeIIIOR', (b) excess c-C6H12 to give (c-C6H11)py (kinetic isotope effect, [KIE] = kc-C6H12/kc-C6D12, 4.6 with t-BuOOH and 1.7 with HOOH), (c) excess R'OOH to give [(PA)2FeIV(OH)(OOR')] (3), then [(PA)2FeIV(O2)] (7) and O2, and (d) O2 to form an adduct, [(PA)2-FeIII(O2)(OOR') + pyH+] (5), that reacts with c-C6H12 to form c-C6H10(O), [K] = 8.2 (t-BuOOH) and 2.1 (HOOH). When PhCH2CH3 or c-C6H10 are the substrates (RH), 5 reacts to form [(PA)2FeIV(OH)(OOR)] (6), which in turn reacts with RH and O2 in a catalytic cycle to give PhC(O)Me or c-C6H8(O) [up to 7 O2 turnovers per iron with FeII(OPPh3)4(2+)]. Species 7 reacts with cis-PhCH = CHPh to give PhCH(O).
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A method using HPLC analysis has been used to compare the level of resveratrol and its derivatives, piceid, pterostilbene and epsilon-viniferin, in grapevine berries of three Vitis vinifera varieties. The concentration of these compounds has been evaluated in healthy and Botrytis cinerea infected grape clusters, both in natural vineyard conditions and in response to UV elicitation.