Lokman Öztürk

Antioxidant Activity of Two Wild Edible Mushrooms (Morchella vulgaris and Morchella esculanta) from North Turkey

The ethanol extracts of Morchella vulgaris (EEMV) and Morchella esculanta (EEME) were analysed for their antioxidant activities in different systems including reducing power, free radical scavenging, superoxide anion radical scavenging, total antioxidant activity, and metal chelating activity. EEMV and EEME had similar reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activity at concentrations of 50, 100, and 150 microg/mL. These various antioxidant activities were compared to standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and alpha-tocopherol. The percent inhibition of different concentrations of EEMV on peroxidation in the linoleic acid system was 85 and 87 % respectively, which was greater than that of 100 and 250 microg/mL of alpha-tocopherol (50 and 77%, respectively) and similar to 250 microg/mL of BHA (85, 87%, respectively). The percent inhibition of different concentrations of EEME on peroxidation in the linoleic acid system was 80 and 87 % respectively, which was greater than that of 100 and 250 microg/mL of alpha-tocopherol (50, 77%) and similar to 250 microg/mL BHA (87%). On the other hand, the percent inhibition of 100 and 250 microg/mL of BHT was 97 and 99%, respectively. In addition, the total phenolic compounds in EEMV and EEME were determined as gallic acid equivalents.

Determination of Antioxidant Activity of Marshmallow Flower (Althaea officinalis L.)

Abstract The antioxidant properties of marshmallow (Althaea officinalis L., Fam. Malvaceae) ethanolic extract was evaluated using different antioxidant tests, including reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities. The extract of marshmallow (A. officinalis L.) exhibited strong total antioxidant activity. The concentration of 50, 100, and 250 µg/mL of ethanol extract of marshmallow (A. officinalis L.) showed 85.5%, 91.2%, and 96.4% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, 100 µg/mL of standard antioxidant such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α‐tocopherol exhibited 94.5%, 99.1%, and 80% inhibition on peroxidation of linoleic acid emulsion, respectively. The extract of marshmallow (A. officinalis L.) had effective reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities at same concentration (50, 100, and 250 µg/mL). Those various antioxidant activities were compared with standard antioxidants such as BHA, BHT, and α‐tocopherol.

Responses of the phenolic compounds of Zea mays under heavy metal stress

Heavy metal toxicity is one of the major abiotic stresses caused by physiological and biochemical changes. Plants have evolved various phytochemical defense mechanisms to cope with this abiotic stress conditions. Phenolic compounds are one of the stress responses and have multiple roles in respect to adaptation of plants to the environment. In the present study, we aimed to evaluate the differential accumulation of various phenolics with HPLC in the leaves of corn exposed to increasing heavy metal doses in the plant growth medium. The application of Cd, Cu, and Pb increased the total phenolics in all treatments compared to control groups. Chlorogenic acid and rutin were the main phenolic compounds in respect to quantifying. However, the contents of caffeic acid, ferulic acid, and vanillic acid were comparatively lower than chlorogenic acid and rutin in all samples. The content of chlorogenic acid significantly increased and rutin slightly increased in the treatment of the heavy metals. The levels of caffeic acid and ferulic acid significantly decreased in all exposures of heavy metals compared to control groups. The content of vanillic acid changed according to heavy metal types and doses in the leaves of corn, and the low doses of Pb and Cd increased the level of vanillic acid. We show that there is a positive correlation with the total phenolic content and chlorogenic acid when the corn is exposed to Pb. Moreover, there are negative correlations between total phenolic compound and caffeic acid, ferulic acid in the application of Cu and Cd.

Alterations in antioxidant enzyme activities and proline content in pea leaves under long-term drought stress

The effects of long-term drought stress on chlorophyll, proline, protein and hydrogen peroxide (H2O2) contents, malondialdehyde (MDA) in terms of lipid peroxidation and on the changes in the activities of antioxidant enzymes such as superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), catalase (CAT, EC 1.11.1.6) and peroxidase (POX; EC 1.11.1.7) in the leaves of pea (Pisum sativum L.) were studied in field conditions. Chlorophyll and protein contents in leaves decreased significantly with increased drought stress. The proline content increased markedly under water deficit. MDA amounts were elevated as a result of water shortage, whereas H2O2 content changed slightly in pea leaves exposed to drought stress. Drought stress markedly enhanced the activities of SOD, CAT and POX but slightly changed the activity of APX. We conclude that in field conditions, long-term water shortage increased the susceptibility to drought in peas.

Purification and some kinetic properties of catalase from parsley (Petroselinum hortense Hoffm., Apiaceae) leaves.

Abstract In this study, catalase (CAT: EC 1.11.1.6) was purified from parsley (Petroselinum hortense) leaves; analysis of the kinetic behavior and some properties of the enzyme were investigated. The purification consisted of three steps, including preparation of homogenate, ammonium sulfate fractionation, and fractionation by DEAE‐Sephadex A50 ion exchange chromatography. The enzyme was obtained with a yield of 9.5% and had a specific activity of 1126 U (mg proteins)−1. The overall purification was about 5.83‐fold. A temperature of 4°C was maintained during the purification process. Enzyme activity was spectrophotometrically measured at 240 nm. In order to control the purification of the enzyme, SDS‐polyacrylamide gel electrophoresis was carried out in 4% and 10% acryl amide for stacking and running gel, respectively. SDS‐polyacrylamide gel electrophoresis showed a single band for the enzyme. The molecular weight was found to be 183.29 kDa by Sephadex G‐200 gel filtration chromatography. The stable pH, optimum pH, and ionic strength were determined for phosphate and Tris‐HCl buffer systems. In addition, KM and Vmax values for H2O2, at optimum pH and 25°C, were determined by means of Lineweaver‐Burk plots.

Gene expression analysis of metallothionein and mineral elements uptake in tomato (Solanum lycopersicum) exposed to cadmium

Heavy metals such as Cd are considered to be the most important pollutants in soil contamination. Cd is a non-essential element adversely affecting plant growth and development, and it has caused some physiological and molecular changes. Metallothioneins (MTs) are low molecular weight, cysteine-rich, and metal binding proteins. In this study, we aimed to evaluate the MT gene expression levels and minerals uptake in the tissues of Solanum lycopersicum exposed to Cd. The transcriptional expression of the MT genes was determined by real-time quantitative PCR. The MT genes were regulated by the Cd and the mineral elements uptake changed tissue type and applied doses. The MT1 and MT2 transcript levels increased in the roots, the leaves and the fruits of the tomato. The MT3 and MT4 transcript pattern changed according to the tissue types. The Cd treatment on the growth medium increased the Mg, Ca, and Fe content in both the leaves and fruits of the tomato. However, the Cd affected the mineral levels in the roots depending on the mineral types and doses. Also, the Cd content increased in the roots, the leaves, and the fruits of the tomato, respectively. The results presented in this study show that Cd has synergistic and/or antagonistic effects on minerals depending on the tissue types. These results indicate that the MT1 and MT2 expression pattern increased together with the Mg, Ca, and Fe content in both the leaves and the fruits of the tomato.

Effect of polyamines on glutathione reductase activity in spinach.

The effects of polyamines (putrescine, spermidine and spermine) on glutathione reductase (glutathione: NADP+ oxidoreductase, EC 1.8.1.7; GR) activity of spinach leaves (Spinacia oleracea L. cv. Gladiator) were investigated under in vivo and in vitro conditions. Spinach was grown in sand culture under controlled conditions for 30 d. In in vivo assays 30-day-old plants were sprayed with polyamines once, and leaves were harvested 1, 5, 10 and 15 d after treatment. The three polyamines decreased the GR activity to different degrees, depending on time after application, type of compound and their concentration. In order to study whether or not polyamines can exert a direct effect on GR, the enzyme was partially purified from spinach leaves and incubated with polyamines in the reaction medium. Under these in vitro conditions, GR was inhibited by polyamines in a polyamine type- and concentrationdependent manner. Interestingly, spermine exerted the most intense inhibitory effect in both in vivo and in vitro experiments. It is proposed that the early decrease of glutathione reductase activity in leaves treated with polyamines can be due to a direct interaction of these compounds with the enzyme

Expression analysis of metallothioneins and mineral contents in tomato (Lycopersicon esculentum) under heavy metal stress.

BACKGROUND Heavy metals are considered to be the most important pollutants in the contamination of soils; they adversely affect plant growth and development and cause some physiological and molecular changes. The contamination of agricultural soils by heavy metals has changed the mineral element content of vegetables. Plant metallothioneins (MTs) are thought to have the functional role in heavy metal homeostasis, and they are used as the biomarkers for evaluating environmental pollution. We aimed to evaluate the expression of MT isoforms (MT1, 2, 3 and 4) and some mineral element composition of tomato roots, leaves and fruits exposed to copper and lead. RESULTS Heavy metal applications increased MT1 and MT2 gene expressions compared to the control in the tissues of tomato. The highest level of MT1 and MT2 transcripts was found in roots and leaves, respectively. The expression of MT3 is induced in roots, leaves and fruits except for Pb treatment in roots. MT4 expression increased in fruits; however, other tissues did not show a clear change. Our results indicated that Cu content was higher than Pb in all tissues of tomato. The lower doses of Cu (10 ppm) increased the content of Mg, Fe, Ca and Mn in roots. Pb generally increased the level of minerals in leaves and fruits, but it decreased Mg, Mn and Fe contents in roots. CONCLUSION Both heavy metals not only moved to aerial parts but also caused alterations to mineral element levels. These results show that MT transcripts are regulated by Cu and Pb, and expression pattern changes to MT isoforms and tissue types.