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    Öğe
    Isolation, structure elucidation and bioactivity of schischkiniin, a unique indole alkaloid from the seeds of Centaurea schischkinii
    (Pergamon-Elsevier Science Ltd, 2005) Shoeb, M; Celik, S; Jaspars, M; Kumarasamy, Y; MacManus, SM; Nahar, L; Paul, KTLD
    Reversed-phase HPLC analysis of the methanol extract of the seeds of Centaurea schischkinii afforded a novel indole alkaloid, named schischkiniin (1), together with four lignans, arctiin (2), matairesinoside (3), matairesinol (4), and arctigenin (5), and three flavonoids, astragalin (6), afzelin (7) and apigenin (8). While the structure of schiskiniin (1) was established unequivocally by UV, HRFABMS and a series of ID and 2D NMR analyses, all known compounds were readily identified by comparison of their spectroscopic data with literature data. The free radical scavenging properties of these compounds were assessed using the DPPH assay, and their general toxicity and cytotoxicity were evaluated, respectively, by brine shrimp lethality and MTT cytotoxicity assays with CaCo-2 colon cancer cell lines. Arctigenin (5) exhibited promising in vitro anticancer activity (IC50=7 mu M) while with schischkiniin (1) the activity was of moderate level (IC50 = 76 mu M). (c) 2005 Elsevier Ltd. All rights reserved.
  • [ X ]
    Öğe
    Two acylated flavonoid glycosides from Stachys bombycina, and their free radical scavenging activity
    (Govi-Verlag Pharmazeutischer Verlag Gmbh, 2005) Delazar, A; Celik, S; Göktürk, RS; Unal, O; Nahar, L; Sarker, SD
    Preparative reversed-phase HPLC analysis of the methanol extract of the aerial parts of Stachys bombycina (Lamiaceae) afforded two acylated flavonoids glycosides, chrysoeriol 7-O[6-O-acetyl-beta-D-allopyranosyl]-(1 --> 2)-beta-D-glucopyranoside (1) and apigenin 7-O-beta-D-(6-p-coumaroyl)-glucopyranoside (2), the former being a new natural product. The structures of these compounds were elucidated unambiguously by UV spectroscopic analyses using shift reagents, ESIMS, and 1D and 2D NMR spectroscopic techniques. The free radical scavenging activity of 1 and 2 compounds were assessed by DPPH assay, and the RC50 values were 1.25 x 10(-2) and 7.69 x 10(-4) mg/mL, respectively.