Polat Kose, Leyla; Bingol, Zeynebe; Kaya, Ruya; Goren, Ahmet C.; Akincioglu, Hulya; Durmaz, Lokman; Koksal, Ekrem; Alwasel, Saleh H.; Gülçin, İlhami

In the first stage of the manuscript, we aimed to examine antioxidant capacity and anticholinergic properties of avocado (Folium perseae) leaves. Avocado leaf was extracted by water (WEFP) and ethyl alcohol (EEFP) and antioxidant activity was determined using by several antioxidant assays including DPPH· and ABTS•+ radical scavenging assays, Cu2+-Cu+ reducing, Fe3+-Fe2+ reducing, and FRAP reducing activities. Avocado leaf extracts demonstrated antioxidant activity and anticholinergic activities, while α-tocopherol, BHT, trolox, and BHA were used as positive antioxidant controls. In the second part of this study, the inhibition effects of WEFP and EEFP were valuated against acetylcholinesterase and butyrylcholinesterase enzymes, which catalyze the breakdown of choline esters (i.e. neurotransmitters). This study obviously showed that avocado leaf extracts had effective antioxidant, antiradical, and anticholinergic influences.

Gulcin, Ilhami; Kaya, Ruya; Goren, Ahmet C.; Akincioglu, Hulya; Topal, Meryem; Bingol, Zeynebe; Cetin Çakmak, Kader; Ozturk Sarikaya, Sevim B.; Durmaz, Lokman; Alwasel, Saleh

Ethanolic (EEC) and aqueous (WEC) extracts of cinnamon (Cinnamomum verum) were evaluated for their antioxidant profiles by eight distinguished bioanalytical antioxidant methods. Their inhibitory effects were tested against some enzymes including acetylcholinesterase, butyrylcholinesterase, α-glycosidase and α-amylase, which linked to different diseases. Additionally, the antioxidant properties were determined and polyphenolic compositions of the both extracts were evaluated by LC-MS/MS analysis. According to the LC-MS/MS experiments, thirteen compounds were found in WEC and EEC. Also, p-hydroxybenzoic acid (321.1 mg/kg extract), p-coumaric acid (291.4 mg/kg extract), and pyrogallol (142.4 mg/kg extract) were found to be the most abundant ingredients in the WEC. On the other hand, pyrogallol (264.3 mg/kg extract), ferulic acid (224.7 mg/kg extract) and p-coumaric acid (170.2 mg/kg extract) were found as the most plentiful chemicals in the EEC. For the estimation of the antioxidant capacities of the both extracts (WEC and EEC), DPPH· and ABTS•+ scavenging activities, as well as Fe3+-Fe2+, and Cu2+-Cu+ reducing assays were studied. The IC50 values of the WEC and EEC indicated that they were potent effective DPPH· (21. 25 and 15.71 μg/mL) and ABTS•+ (6.52 and 5.79 μg/mL) scavengers, as well as AChE (221.33 and 110.26 μg/mL), BChE (461.69 and 94.93 μg/mL), α-glycosidase (206.86 and 220.00 μg/mL) and α-amylase (189.86 and 200.86 μg/mL) inhibitors. As a conclusion, both EEC and WEC had rich phenolic contents and demonstrated effective anticholinergic, antidiabetic and antioxidant effects.

Altay, Ahmet; Koktepe, Tubanur; Durmaz, Lokman; Topal, Fevzi; Gülçin, İlhami; Köksal, Ekrem

Cress (Lepidium sativum) is an annual herb from Brassicaceae family, and in some regions. It is known as peppergrass, garden cress, garden pepper-cress, pepperwort, or poor man’s pepper. Cress is an important medicinal plant in some countries including Turkey. This plant has major scientific and therapeutic significance. Peroxidase (POD, E.C.1.11.1.7) is an oxidor-eductase enzyme produced by a number of organisms. In this study, POD enzyme was purified from cress by ammonium sulphate precipitation, gel filtration, and CM-Sephadex ion-exchange chromatographies. K m and V max values were calculated from the Lineweaver-Burk graph for H 2 O 2 and guaiacol substrates and the substrate specificity of POD was investigated. The results showed that substrate specificity of H 2 O 2 is better than substrate specificity of guaiacol for this enzyme. The inhibition effects of three cations (Al 3+ , Cu 2+ , and Cr 3+ ) and one organic compound of cetyl trimethylammonium bromide were performed and their inhibition types were determined. Finally, optimum pH, optimum temperature, optimum ionic strength, and stable pH were determined.

Köksal, Ekrem; Bursal, Ercan; Gülçin, İlhami; Korkmaz, Mustafa; Çağlayan, Cüneyit; Gören, Ahmet C.; Alwasel, Saleh H.

Like tea, the leaves of Turkish thyme (Thymus vulgaris) can be boiled in water to produce an extract. This is widely used as syrup for the treatment of coughs and bronchitis at alternative medicine clinics in many parts of the world. In the current study, we assessed the phenolic content and antioxidant activity of thyme. The antioxidant activities of both ethanol and aqueous extracts of thyme were determined using various in vitro methods. The total phenolic and total flavonoid contents were determined to be a gallic acid equivalent and a quercetin equivalent, respectively. Finally, the quantities of the phenolic compounds were detected using high-performance liquid chromatography and tandem mass spectrometry. The total phenolic compounds in the aqueous extract and ethanol extracts of Turkish thyme were 256.0 μg gallic acid equivalent/mg dried extract and 158.0 μg gallic acid equivalent/mg dried extract, respectively. Conversely, the total flavonoid compounds in both extracts were 44.2 μg and 36.6 μg quercetin equivalent/mg dried extract, respectively. For the first time, we determined phenolic contents and investigated the antioxidant potential of thyme. The results indicate that Turkish thyme is a good dietary source with phenolic properties.

Altın, Sevgi; Tohma, Hatice; Gülçin, İlhami; Köksal, Ekrem

The purification and characterization of peroxidase is currently growing interests since peroxidases have implications in various industrial and biochemical applications. In this study, wheat peroxidase was purified using (NH4)2SO4 precipitation, CM-Sephadex cation exchange, and gel filtration chromatographies. Enzyme purity and molecular mass were checked by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Enzyme kinetics was studied using two substrates: guaiacol and hydrogen peroxide (H2O2). Km and Vmax values were calculated from Lineweaver-Burk graph for each substrate. Wheat peroxidase activity has been enhanced 284-fold. Wheat peroxidase had molecular mass of 38.8 kDa. Km values for guaiacol and H2O2 were found as 2.467 mM and 7.307 mM, respectively. The pH and temperature optima were 5.5 and 40.0°C, respectively. Also, the enzyme was highly inhibited by citric acid and Cetyltrimethylammonium bromide.

Köktepe, Tubanur; Altın, Sevgi; Tohma, Hatice; Gülçin, İlhami; Köksal, Ekrem

In this study, a cationic soluble peroxidase (POD) was homogeneously purified and biochemically characterized. The enzyme purification involved the combination of (NH4)2SO4 precipitation, CM-Sephadex cation exchange, and gel filtration chromatography. The purity of the enzyme was examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, and one single prominent band was obtained with a molecular weight of approximately 45 kDa. The thermal and pH stability showed that the enzyme was stable at pH 5.0 and at 40°C, respectively. The activity remained stable at pH 4.0 at least for 10 days. Km and Vmax values were calculated from Lineweaver–Burk graph for each substrate. POD exhibited Km values of 0.0154 and 0.065 mM for guaiacol and H2O2, respectively. The enzyme was highly inhibited by sodium azide. This study could enrich the literature regarding the properties of POD from haricot bean that could be applicable to biomedical analysis.

Yıldız, Pınar Oğuzhan; Yangılar, Filiz

In this study, the effect of different whey protein concentrate coating formulations (with or without glycerol) on the storage of fillets over a period of 15 days at 4ºC was investigated. Fillets were conducted to microbiological, chemical, and sensory analyses. Difference in microbiological and chemical changes between samples was found to be significant (p < 0.05) during storage period. The Y and Z were preferred more by the panellists, while C samples received the lowest scores. According to the results of microbiological analyses, shelf life of fillets was estimated at 6, 9, 12, and 15 days for C, X, Y, and Z samples, respectively.

Koksal, Ekrem; Bursal, Ercan; Aggul, Ahmet Gokhan; Gulcin, Ilhami

Peroxidase (EC 1.11.1.7; donor: hydrogen peroxide oxidoreductase) is an oxidoreductase enzyme found in many fruits and vegetables. This enzyme was purified from sweet gourd (Cucurbita moschata Lam. Poiret) by ammonium sulphate precipitation and CM-Sephadex ion-exchange chromatography. Furthermore, optimum pH, optimum temperature, optimum ionic strength, stable pH, and stable temperature conditions were determined as 7.2, 50°C, 0.4 M, 8.0, and 40°lC, respectively. The molecular weight (MW) of the enzyme was estimated to be 85 kDa by SDS-PAGE method. The values of Km and Vmax were calculated from the Lineweaver-Burk graph for guaiacol/H2O2 substrate patterns.

Şisecioglu, Melda; Gülçin, Ilhami; Çankaya, Murat; Ozdemir, Hasan

L-Adrenaline belongs to a group of compounds known as catecholamines, which play an important role in the regulation of the physiological process in living organisms. In the present study, the inhibitory effect of L-adrenaline on lactoperoxidase was examined. Lactoperoxidase (E.C.1.11.1.7) was purified from bovine milk with three consecutive steps: Amberlite CG-50 resin, CM-Sephadex C-50 ion-exchange, and Sephadex G-100 gel filtration chromatography. Lactoperoxidase was purified with a yield of 42.18%, a specific activity of 30.33 EU/mg proteins, and 20.77 purification fold. Enzyme purity was determined with SDS-PAGE, where a single band was observed. The Rz (A 412/A280) value for lactoperoxidase was 0.9. The effect of L-adrenaline on lactoperoxidase was determined using ABTS as a chromogenic substrate. The half maximal inhibitory concentration (IC50) value and an inhibition constant (Ki) values for L-adrenaline were 34.5 and 2.26 μM, respectively. L-Adrenaline was found to be a non-competitive inhibitor.

Gungor, Neva; Sengul, Memnune

In this study, total phenolic content, antioxidant activity, mineral content and selected physicochemical properties of three white mulberry phenotypes (Morus alba L.) grown in Turkey were measured. Moisture, total soluble solids, total sugar, sucrose, reducing sugar, protein, ash, pH, titratable acidity, color (L, a, b), vitamin C, total phenolic, antioxidant activity of fruits were determined between 72.85-79.75 g/100 g fresh fruit, 21.25-28.50 g/100 g fresh fruit, 12.18-17.02 g/100 g fresh fruit, 1.57-4.36 g/100 g fresh fruit, 9.42-15.46 g/100 g fresh fruit, 0.82-0.89 g/100 g fresh fruit, 2.20-2.65 g/100 g fresh fruit, 5.70-5.86, 0.25-0.28 g/100 g fresh fruit, 31.24-68.69, -2.46 to 15.68, 4.58-21.74, 10.15-21.50 mg/100 g fresh fruit, 18.16-19.24 g gallic acid equivalent/mg of sample, and 33.96-38.96%, of sample respectively. Fruits were generally found high in P and low in Ca.