Browsing by Author "Guclu, Kubilay"

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Antioxidant Capacities of Herbal Plants Used in the Manufacture of Van Herby Cheese: 'otlu Peynir
(Taylor & Francis inc, 2008) Celik, S. Esin; Ozyurek, Mustafa; Altun, Mehmet; Bektasoglu, Burcu; Guclu, Kubilay; Berker, K. Isil; Apak, Resat
The traditional Van herby cheese incorporates herbs mainly consisting of Allium species as antimicrobial and flavouring aids. The total antioxidant capacities of 16 different herbs (8 species) collected from different locations were assayed for the first time by CUPRAC, ABTS/persulfate, FRAP, and Folin methods. The assay results correlated well among each other, because all were electron-transfer assays. The highest results were obtained with Folin having the highest redox potential. The second highest results were with CUPRAC, especially for the allium sp., because the sulfur containing antioxidants in allium could be best assayed with CUPRAC, whereas FRAP was nonresponsive to thiol-type compounds. The order of CUPRAC antioxidant capacities as trolox equivalents was thymus sp. chaerophyllum sp. allium sp. prangos sp. ferula sp. On the other hand, the order of Folin findings was thymus sp. allium sp. chaerophyllum sp. ferula sp. prangos sp.
Microwave-Assisted Extraction of Polyphenolics From Some Selected Medicinal Herbs Grown in Turkey
(Acg Publications, 2018) Baki, Sefa; Tufan, Ayse Nur; Altun, Mehmet; Ozgokce, Fevzi; Guclu, Kubilay; Ozyurek, Mustafa
The effect of microwave-assisted extraction (MAE) process on the antioxidant capacity/activity of three medicinal herbs from Turkey was investigated by electrochemical differential pulse voltammetric (DPV)CUPric Reducing Antioxidant Capacity (CUPRAC) assay. The optimal extraction time, temperature and solvent type were 6 min, 80 degrees C and 80% (v/v) methanol (MeOH), respectively. Microwave-assisted extracts of herbs (Hypericum scabrum L., Papaver fugax Poiret var. platydiscus Cullen, and Achillea vermicularis Trin.) were screened for total antioxidant capacity (TAC), total phenolic content (TPC) and ROS scavenging activities by employing different in vitro spectrophotometric assays. A positive correlation was observed between TACCUPRAC and TPC (R-2 = 0.972). Similarly, a positive correlation was observed between TAC-CUPRAC and free radical scavenging (FRS) activity (R-2 = 0.977). The order of FRS activities of tested samples was as follows: Hypericum scabrum L. > Achillea vermicularis Trin. > Papaver fugax Poiret var. platydiscus Cullen. These results suggest that these medicinal herbs provide promising antioxidant potentials as potential natural preservative agents in pharmaceutical industries.