Browsing by Author "Tamer U."

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Determination of isoflavone content by hplc-uv method and in vitro antioxidant activity of red clover (trifolium pratense l.)
(2013-12-01) Küçükboyaci N.; Kadioǧlu O.; Adigüzel N.; Tamer U.; Güvenç A.; Bani B.
In this study, the methanol and acid hydrolyzed methanol extracts prepared from the aerial parts of two varieties of Trifolium pratense (red clover) collected from different parts of Turkey, namely T. pratense L. var. pratense and T. pratense L. var. sativum Schreb., have been analyzed to determine the concentrations of four isoflavones, daidzein (D), genistein (G), formononetin (F) and biochanin A (B). A RP-HPLC-UV method for the determination of these isoflavones in red clover was developed. Chromatographic separation was carried out by using a gradient system consisting of 0.3 % acetic acid and methanol on a reversed phase column, Supelcosil™ LC-18 (15 cm x 4.6 mm id, 5μm). The highest content of total D, G, F, and B were found as 0.0447, 0.0115, 0.0251 and 0.0039 % in T. pratense var. pratense, respectively. Antioxidant capacity of the methanol extracts of aerial parts of plant samples was also studied. Studied extracts were found to possess some antioxidant activities, as determined by the DPPH free radical scavenging test, thiobarbituric acid and trolox-equivalent antioxidant capacity assays. The phenolic contents of the samples were determined using Folin-Ciocalteu's reagent.
Quantitative determination of isoflavones by HPLC-UV method and antioxidant activity of trifolium longidentatum
(2014-01-01) Küçükboyaci N.; Ilginer O.; Torul H.; Tamer U.; Adigüzel N.; Bani B.; Köroǧlu A.
In this study, aerial parts of Trifolium longidentatum Nábělek (Fabaceae) were quantitatively analyzed for their content of four isoflavones, daidzein (D), genistein (G), formononetin (F) and biochanin A (B), by the use of developed RP-HPLC-UV method. The chromatographic separation was performed using a gradient system with a mobile phase of methanol, acetate buffer (pH=4.75) and acetonitrile with on the reversed phase column, Agilent Eclipse XDB-18 (15 cm × 4.6 mm i.d.). The contents of D, G, F and B in the aerial parts of T. longidentatum were determined as 0.0095, 0.0056, 0.0021 and 0.0073 %, respectively. Antioxidant potential of the methanol extract prepared from the aerial parts of the plant was also investigated with different in vitro methods, namely DPPH radical scavenging activity, lipid peroxidation inhibition and trolox equivalent antioxidant capacity assays. As a consequence, it was observed that the methanol extract of T. longidentatum had in vitro antioxidant activities in these methods. The phenolic content of the extract was also measured as 53.98 ± 0.95 mg gallic acid/g extract by the Folin-Ciocalteu's reagent.