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    Cellular reactive oxygen species inhibitory constituents of Hypericum thasium Griseb
    (Pergamon-Elsevier Science Ltd, 2009) Demirkiran, Ozlem; Mesaik, M. Ahmed; Beynek, Hayrettin; Abbaskhan, Ahmed; Choudhary, M. Iqbal
    The phytochemical investigation of the ethyl acetate extract of Hypericum thasium has led to the characterization of four benzophenone derivatives 1-4, a known benzophenone 5 and four known flavonoids, quercetin (6), quercitrin (7), isoquercetin (8), and 3, 8-biapigenin (9). Lucigenin- and luminal-based chemiluminescence assays were employed to monitor the inhibitory activity of these compounds towards the production of reactive oxygen species (ROS) by human polymorphoneutrophils (PMNs). The assay results showed that benzophenones 1 and 3 are extracellular inhibitors of ROS production, while flavonoids 6, 8, and 9 can modulate intracellular ROS production. (C) 2008 Elsevier Ltd. All rights reserved.
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    Immunosupressive Phenolic Constituents from Hypericum montbretii Spach.
    (Acg Publications, 2013) Demirkiran, Ozlem; Mesaik, M. Ahmad; Beynek, Hayrettin; Abbaskhan, Ahmed; Choudhary, M. Iqbal
    The MeOH extract of aerial parts of H. monbretii Spach. have yielded quercetin (1), kaempferol (2), quercitrin (3), hyperin (4), myricitrin (5), rutin (6), I 3 II 8 '' biapigenin (7), methyl chlorogenate (8), 5-O-p-coumaroylquinic acid (9), and chlorogenic acid (5-O-caffeoyl quinic acid) (10), mangiferin (11), and shikimic acid (12). Three compounds 1, 2 and 4 were found to have an immunomodulating inhibitory activity on the oxidative burst response of human neutrophils, as well on mouse peritoneal macrophages. Effects of compounds on whole blood phagocytes activity was found to be with IC50 ranging between 8.0-12.2 mu g/mL. Only compounds 1, and 2 were found to interfere with T-cell proliferation, and IL-2 release in PHA activated peripheral blood mononuclear cells system. To the best of our knowledge, this is the first report of phytochemical and biological activity study on H. montbretii Spach.
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    Potent tyrosinase inhibitors from Trifolium balansae
    (Taylor & Francis Ltd, 2006) Sabudak, Temine; Khan, Mahmut Tareq Hassan; Choudhary, M. Iqbal; Oksuz, Sevil
    Trifolium balansae ( Leguminosae) yielded a phytylester, phytyl-1-hexanoate, three steroids, stigmast-5-ene-3 beta,26-diol, stigmast-5-ene-3-ol and campesterol, and an alcohol, pentacosanol which were reported for the first time from T. balansae. The structures of the isolates were determined by 1D and 2DNMR techniques and MS spectroscopy. Compounds 1 - 5 were tested for their enzyme tyrosinase activity. While compounds 1 and 5 did not show any inhibition against the enzyme tyrosinase, compounds 2, 3, and 4 exhibited potent inhibition against tyrosinase. Highly potent ( IC50 = 2.39 mu M) inhibition was found by compound 2, when compared with the standard tyrosinase inhibitors Kojic acid and L-mimosine.
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    Structure elucidation of two new unusual monoterpene glycosides from Euphorbia decipiens, by 1D and 2D NMR experiments
    (Wiley-Blackwell, 2011) Demirkiran, Ozlem; Topcu, Gulacti; Hussain, Javid; Ahmad, Viqar Uddin; Choudhary, M. Iqbal
    Two new unusual monoterpene glycosides, (Z)-3,6-dimethyl-3-(beta-D-O-glucosylmethylene)cyclohept-4-ene-1-one (1) and 3,6-dimethyl-3-(beta-D-O-glucosylmethylene) cycloheptanone (2) have been isolated along with five known compounds, 3-hydroxy-4-methoxybenzoic acid, 6,7-dihydroxycoumarin, luteolin, apigenin 5-O-alpha l-L-rhamnoside, and pinocembrin-7-O-rutinoside from ethyl acetate extract of Euphorbia decipiens. The structures of the isolated compounds were elucidated by extensive 1D- and 2D-NMR, and mass spectroscopic analyses. Copyright (C) 2011 John Wiley & Sons, Ltd.
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    Tyrosinase Inhibitory Activity of Chemical Constituents of Euphorbia macrostegia
    (Springer, 2014) Demirkiran, Ozlem; Topcu, Gulacti; Azarpira, Ali; Choudhary, M. Iqbal
    The chloroform extract of the aerial parts of E. macrostegia has yielded a new compound, 2-(4-hydroxyphenyl)-ethylhentriacontanoate (1), along with hentriacontan-1-ol (2), lupenone (3), cycloart-22-ene-3,25-diol (4), 3,3',4'-tri-O-methylellagic acid (5), cleomiscosin (6), and glucoclioniasterol (stigmast-5-en-3-O-beta-glucopyranoside) (7), and from the ethyl acetate extract of aerial parts of the plant isoquercetin (8), quercetin-3-O-alpha-arabinofuranoside (avicularin) (9), and rutin (10) have been isolated. Compounds 1-10 were tested for their tyrosinase inhibitory activity, and 2 exhibited an IC50 value of 71.4 mu M, almost comparable to standard kojic acid (IC50 58.2 mu M). Compounds 1-4 also showed good activity with IC50 values of 77.2, 78.6, 71.4, and 77.5 mu M, respectively.