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- MakaleAçık Erişim2016Antioxidant activity of taxifolin: An activity-structure relationship
Topal, Fevzi; Nar, Meryem; Gocer, Hulya; Kalin, Pinar; Kocyigit, Umit M.; Gülçin, Ilhami; Alwasel, Saleh H.
Taxifolin is a kind of flavanonol, whose biological ability. The objectives of this study were to investigate the antioxidants and antiradical activities of taxifolin by using different in vitro bioanalytical antioxidant methods including DMPD•+, ABTS•+, and DPPH•-scavenging effects, the total antioxidant influence, reducing capabilities, and Fe2+-chelating activities. Taxifolin demonstrated 81.02% inhibition of linoleic acid emulsion peroxidation at 30 μg/mL concentration. At the same concentration, standard antioxidants including trolox, α-tocopherol, BHT, and BHA exhibited inhibitions of linoleic acid emulsion as 88.57, 73.88, 94.29, and 90.12%, respectively. Also, taxifolin exhibited effective DMPD•+, ABTS•+, and DPPH•-scavenging effects, reducing capabilities, and Fe2+-chelating effects. The results obtained from this study clearly showed that taxifolin had marked antioxidant, reducing ability, radical scavenging and metal-chelating activities. Also, this study exhibits a scientific shore for the significant antioxidant activity of taxifolin and its structure-activity insight.
- MakaleAçık Erişim2016Antioxidant, antiradical, and anticholinergic properties of cynarin purified from the Illyrian thistle (Onopordum illyricum L.)
Topal, Meryem; Gocer, Hulya; Topal, Fevzi; Kalin, Pinar; Köse, Leyla Polat; Gulçin, Ilhami; Çakmak, Kader C.; Küçük, Murat; Durmaz, Lokman; Gören, Ahmet C.
Cynarin is a derivative of hydroxycinnamic acid and it has biologically active functional groups constituent of some plants and food. We elucidated the antioxidant activity of cynarin by using different in vitro condition bioanalytical antioxidant assays like DMPD•+, ABTS•+, DPPH• and H2O2 scavenging effects, the total antioxidant influence, reducing capabilities, Fe2+ chelating and anticholinergic activities. Cynarin demonstrated 87.72% inhibition of linoleic acid lipid peroxidation at 30 g/mL concentration. Conversely, some standard antioxidants like trolox, tocopherol, butylated hydroxytoluene (BHT), and butylated hydroxyanisole (BHA) exhibited inhibitions of 90.32, 75.26, 97.61, 87.30%, and opponent peroxidation of linoleic acid emulsion at the identical concentration, seriatim. Also, cynarin exhibited effective DMPD•+, ABTS•+, DPPH•, and H2O2 scavenging effects, reducing capabilities and Fe2+ chelating effects. On the contrary, IC50 and Ki parameters of cynarin for acetylcholinesterase enzyme inhibition were determined as 243.67 nM (r2: 0.9444) and 39.34 ± 13.88 nM, respectively. This study clearly showed that cynarin had marked antioxidant, anticholinergic, reducing ability, radical-scavenging, and metal-binding activities.
- MakaleYalnız künye2013Radical scavenging and antioxidant capacity of serotonin
Sarikaya, S. Beyza Öztürk; Gülçin, Ilhami
Serotonin is a monoamine neurotransmitter and biochemically derived from tryptophan. The present paper examines the in vitro antioxidant and radical scavenging capacity of serotonin using different in vitro methodologies. For the determination of antioxidant activity of serotonin, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2́-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by Fe3+-Fe2+ transformation method, superoxide anion radical scavenging by riboflavin-methionine-illuminate system, H2O2 scavenging and ferrous ions (Fe +) chelating activities of serotonin were performed. Also, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analog of α-tocopherol, were used as the reference antioxidant radical scavenger compounds. Serotonin completely inhibited lipid peroxidation of a linoleic acid emulsion at 15 μg/mL concentration. On the other hand, the above mentioned standard antioxidants displayed inhibition of 92.2, 99.6, 84.6 and 95.6% on peroxidation of linoleic acid emulsion, respectively at the 45 μg/mL concentration. In addition, serotonin was effective in DPPH· scavenging, ABTS•+ radical scavenging, superoxide anion radical scavenging, H2O2 scavenging, ferric ions (Fe3+) reducing power and metal chelating on ferrous ions (Fe+) activities. Also, those various antioxidant activities were compared to BHA, BHT α-tocopherol and trolox as references antioxidant compounds.
- MakaleYalnız künye2011Polyphenol contents and antioxidant properties of medlar (Mespilus germanica L.)
Gülçin, Ilhami; Topal, Fevzi; Sarikaya, S. Beyza Öztürk; Bursal, Ercan; Bilsel, Gökhan; Gören, Ahmet C.
Medlar is the fruit of Mespilus germanica L. in the family of Rosaceae. The present study outlines that the native medlar (Mespilus germanica L.) fruits an extremely rich source of antioxidants. In this study, antioxidant and antiradical property of medlar fruits were evaluated. Total phenolics and flavonoids amounts in lyophilized extract of medlar (LEM) fruits were calculated as gallic acid and quercetin equivalents, respectively. Antioxidant and radical scavenging activity of LEM were investigated using different in vitro assays including 1,1-diphenyl-2-picryl-hydrazyl (DPPH·), N,N-dimethyl-p-phenylenediamine (DMPD•+), and superoxide anion radicals (O2•-) scavenging activity, hydrogen peroxide (H2O2), ferric ions (Fe 3+) and cupric ions (Cu 2+) reducing ability, Fe 3+ -TPTZ reducing ability, ferrous ions (Fe2+) chelating activity as trolox equivalent. In addition, quantitative amounts of caffeic acid, ferulic acid, syringic acid, ellagic acid, quercetin, α-tocopherol, pyrogallol, p-hydroxybenzoic acid, vanillin, p-coumaric acid, gallic acid and ascorbic acid in LEM were detected by high performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). The presence of these antioxidant compounds can be considered as a quality parameter for edible medlar fruits.