Ahmet Mavi

Isolation and characterization of antioxidant phenolic compounds from the aerial parts of Hypericum hyssopifolium L. by activity-guided fractionation.

Dried methanol extract of Hypericum hyssopifolium subsp. elongatum var. elongatum was dissolved in distilled water, and then fractioned by re-extracting with petroleum ether, chloroform, and ethyl acetate, subsequently. Antioxidant and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities of these fractions were determined, in vitro. The amounts of total phenolic compounds were also determined. None of these fractions showed antioxidant activity, in contrast water and ethyl acetate fractions acted as prooxidant. However, the ethyl acetate fraction exhibited the highest DPPH radical-scavenging activity and the amount of its total phenolic compound was highest, too. Therefore, ethyl acetate fraction was subjected to further separation by chromatographic methods. Thus, five flavonoids (I3,II8-biapigenin, quercetin, quercetin-3-O-alpha-L-arabinofuranoside, quercetin-3-O-beta-D-galactopyranoside, quercetin-3-O-beta-D-galactopyranoside-7-O-beta-D-glucopyranoside) and a napthodianthrone (hypericin) were isolated, and their structures were determined by UV, IR, NMR, and MS spectroscopic methods. All isolated compounds showed antioxidant and DPPH radical-scavenging activities. Although, I3,II8-biapigenin and hypericin were able to show highest antioxidant activity, they had the lowest DPPH radical-scavenging activities. From these results, it can be suggested that these compounds may be used as potential antioxidants. In addition, the petroleum ether fraction was subjected to silica gel column chromatography (CC). Then, n-dotriacontanyl hexadecanoate, bis(2-methylheptyl) phthalate, and beta-sitosterol were isolated from it. It is of interest to present the spectral data of bis(2-methylheptyl) phthalate first time in the present study.

Antioxidant Properties of Some Medicinal Lamiaceae (Labiatae) Species

Abstract In this study, antioxidant properties of Thymus sipyleus. Boiss. subsp. sipyleus. var. sipyleus., Teucrium chamaedrys L.., Mentha longifolia. (L.) Hudson subsp. longifolia., Salvia limbata. C.A. Meyer, and Thymus fallax. Fisch. & Mey. were investigated. Antioxidant and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, reducing powers, and the amount of total phenolic compounds of the extracts were studied. The highest antioxidant activity was shown by T. chamaedrys. (decoction, IC50: 9.2 µg/ml), and the lowest one was S. limbata. (decoction, IC50: 619.5 µg/ml). The highest DPPH radical scavenging activity was shown by T. fallax. [decoction, IC50S: 56 µg/ml (IC50S is the extract concentration (µg/ml) required for 50% inhibition of the DPPH solution absorbance at 517 nm)] while the lowest one was S. limbata. (decoction, IC50S: 335.8 µg/ml). The highest reducing power and amount of total phenolic compounds was shown by T. chamaedrys. (decoction, 29.9 µg/ml ascorbic acid equivalent, 27.9 µg/ml gallic acid equivalent, respectively), and the lowest one was S. limbata. (decoction, 5.1 µg/ml ascorbic acid equivalent, 9.9 µg/ml gallic acid equivalent, respectively) at 250 µg/ml extract concentration.

Antimicrobial and Antioxidant Activities of Some Plants Used as Remedies in Turkish Traditional Medicine

Abstract The antimicrobial activities of chloroform, acetone, ethanol, and water extracts of 25 plants, mostly used as remedies against various diseases in Turkish traditional medicine, were tested against 10 pathogenic bacteria and one fungus (Candida albicans.) using the disk diffusion method. Among the tested plant species, Ziziphora clinopodioides. Lam (Labiatae), Thymus fallax. Fisch et Mey. (Labiatae), and three Hypericum. species [H. heterophyllum. Vent., H. hyssopifolium. Chaix. subsp. elongatum.(Ledeb.) Woron var. elongatum., and H. scabrum. L.] (Guttiferae) showed antimicrobial activity at a broader spectrum. In particular, chloroform, acetone, and ethanol extracts of Z. clinopodioides. inhibited the growth of all microbial species. Minimal inhibition concentration values of Z. clinopodioides. extracts were also found to be low. The antioxidant activity of the acetone, ethanol, and water extracts of 20 plants was also evaluated by lipid peroxidation inhibition and DPPH free radical scavenging methods. It was found that water, ethanol, and acetone extracts of Z. clinopodioides., T. fallax., three Hypericum. species, Artemisia santonicum. L. (Compositae), and Echinophora tenuifolia. L. subsp. sibthorpiena. (Umbelliferae) have strong antioxidant activities among the tested plant species. In general, there is a correlation between the antioxidant potential and total phenolic contents of the extracts. In light of the current study, it can be concluded that Z. clinopodioides. and T. fallax. may have potential use in the food industry as antioxidants and antimicrobial herbs, as well as pharmaceutical interest.

Promotion by phosphate of Fe(III)- and Cu(II)-catalyzed autoxidation of fructose.

Although the oxidative destruction of glucose and fructose has been studied by several investigators over the past century, the mechanism by which phosphate promotes these oxidation reactions is not known. A wide range of oxidation products have been used to monitor the oxidation of sugars and free radicals have been shown to be involved. The influence of phosphate concentration on the rate of production of free radicals and several sugar oxidation products has been studied. It was found that fructose is much more susceptible to autoxidation than glucose, galactose, or sucrose. The promotion of sugar oxidation by phosphate was found to be iron dependent. Addition of the iron chelators, diethylenetriaminepentaacetic acid (DTPA) and desferrioxamine completely suppressed the oxidation reactions, even at high concentrations of phosphate. Formaldehyde was positively identified as a product of fructose oxidation by HPLC analysis of its acetylacetone adduct. A mechanism is proposed in which phosphate cleaves the oxo bridges of the iron(III)-fructose complex, based on UV spectral analysis and magnetic susceptibility measurements, and thereby catalyzes the autoxidation of fructose.

Effects of some drugs on purified human erythrocyte CuZnSOD and in vitro inhibitiory effect of 5-fluorouracil on leukocyte total SOD activity

The inhibition and activation effects of some drugs on the activities of superoxide dismutase enzymes (SOD) in human erythrocyte and leukocyte cells was investigated. Firstly, CuZnSOD enzyme was purified 837–fold and 12% efficiency from human erythrocytes by ethanol-chloroform treatment to remove hemoglobin and then ion exchange chromatography (DEAE-Sepharose) and copper chelate affinity chromatography techniques. Inhibition or activation effects of fourteen drugs on CuZnSOD was investigated. None of the studied drugs except for 5-fluorouracil showed any effects on the enzyme. 5-fluorouracil showed activation effects on CuZnSOD at 3.33 mg/ml and 4 mg/ml concentrations with 33% and 32% activation, respectively. Leukocytes were isolated from healthy human blood, lysed in liquid nitrogen and the effect of 5-fluorouracil on the lysate SOD activity investigated. 5-Fluorouracil showed inhibition effects on total SOD activity of human leukocytes at 2 mg/ml and 4 mg/ml concentrations with 42% and 62% inhibition, respectively.

Partial Purification and Some Interesting Properties of Glutathione Peroxidase from Liver of Camel ( Camelus dromedarius )

Climate change and increasing temperatures are global concerns. Well adapted to desert life, the camel (Camelus dromedarius) lives most of its life under high environmental stress and represents an ideal model for studying desert adaptation among mammals. Glutathione peroxidase is the principal antioxidant defense system capable of protecting cells from oxidative stress. Glutathione Peroxidase from camel liver was purified (11.64-fold purification with 1.73% yield) and characterized The molecular weight of the enzyme was estimated to be about 69 kDa by gel filtration and 34 kDa by SDS-PAGE, implying dimeric structure of the protein. An optimum temperature of 47°C and an optimum pH of 7.8 were found. This enzyme is a typical SH-enzyme that is inhibited by D,L-dithiothreitol and β-mercaptoethanol and sensitive to bivalent cations. The enzyme had common specificity toward hydroperoxides and high specificity for reduced glutathione. The Km and Vmax values for hydrogen peroxide and reduced glutathione were 0.57 and 2.10 mM and 1.11 and 0.87 U/mg, respectively. The purified enzyme contained 16 ng of selenium per mg of protein. Our results show that the camel glutathione peroxidse exhibits properties different of those reported for other mammalian species. Lower molecular weight, homodimeric structure, higher optimum temperature, relatively low optimum pH, high affinity for hydrogen peroxide at low concentration of reduced glutathione and very low content of selenium could be explained by adaptation of the camel to living in the desert under intense environmental stress.

Purification of camel liver catalase by zinc chelate affinity chromatography and pH gradient elution: An enzyme with interesting properties

Climate change and increasing temperatures are global concerns. Camel (Camelus dromedarius) lives most of its life under high environmental stress in the desert and represent ideal model for studying desert adaptation among mammals. Catalase plays a key role in protecting cells against oxidative stress. For the first time, catalase from camel liver was purified to homogeneity by zinc chelate affinity chromatography using pH gradient elution, a better separation was obtained. A purification fold of 201.81 with 1.17% yield and a high specific activity of 1132539.37U/mg were obtained. The native enzyme had a molecular weight of 268kDa and was composed of four subunits of equal size (65kDa). The enzyme showed optimal activity at a temperature of 45°C and pH 7.2. Thiol reagents, β-Mercaptoethanol and D,L-Dithiothreitol, inhibited the enzyme activity. The enzyme was inhibited by Al3+, Cd2+ and Mg2+, whereas Ca2+, Co2+ and Ni2+ stimulated the catalase activity. Reduced glutathione has no effect on catalase activity. The Km and Vmax of the enzyme for hydrogen peroxide were 37.31mM and 6185157U/mg, respectively. Sodium azide inhibited the enzyme noncompetitively with Ki value of 14.43μM, the IC50 was found to be 16.71μM. The properties of camel catalase were different comparing to those of mammalian species. Relatively higher molecular weight, higher optimum temperature, protection of reduced glutathione from hydrogen peroxide oxidation and higher affinity for hydrogen peroxide and sodium azide, these could be explained by the fact that camel is able to live in the intense environmental stress in the desert.