Ayten Sagiroglu

Sunflower Seed Lipase: Extraction, Purification, and Characterization

Abstract A simple procedure for the extraction of the lipolytic activity from sunflower seed has been developed. Various conditions of extraction have been optimized in order to obtain maximum yield of lipase. A new lipase enzyme was purified by the fractional salt precipitation from the supernatant, dialysis on a cellulose membrane, and gel column chromatography on Sephadex G‐75. The lipase was monomeric, with an apparent M r of 22 kDa and a pI of 8, with the electrophoretic analysis. Kinetics of the enzyme activity versus substrate concentration showed typical lipase behavior, with K m and V max values of 1.33 mM and 555 U/mg. All triglycerides were efficiently hydrolyzed by the enzyme, but this showed a preference towards triglycerides of natural mono unsaturated fatty acids. The optimum temperature, pH, and incubation time for lipolytic activity were 50°C, 7.5, and 5 min, respectively. The stability of the sunflower lipase was investigated under operational and storage conditions. It was found that this enzyme preserved its lipolytic activity at temperatures between at 35–50°C, alkaline pH, and for a period of about four months.

Immobilization of Lipases on Different Carriers and Their Use in Synthesis of Pentyl Isovalerates

Abstract Porcine pancreatic lipase (PPL) and Candida cylindracea lipase (CCL) were immobilized on Celite and Amberlite IRA 938 by deposition from the aqueous solution by the addition of hexane. The influence of the immobilization on the activities of the immobilized lipase derivatives has been studied. The immobilized lipases were used in synthesis of pentyl isovalerates. Various reaction parameters affecting the synthesis of pentyl isovalerates were investigated. The reaction rates were compared with the rates of esterification with free lipases. The immobilized lipases were found to be very effective in the esterification reaction. The lipases immobilized on Celite 545 exhibited better operational stabilities than that of immobilized on Amberlite IRA‐938.

ANTIOXIDANT POTENTIAL OF DIFFERENT DILL (ANETHUM GRAVEOLENS L.) LEAF EXTRACTS

Dill (Anethum graveolens L.) have been extensively used in salads, soups, and pickles for its aromatic odor and flavor. Recently, interest in plant-derived food additives has grown. In this study, the possible antioxidant properties of water, ethanol, and acetone extracts of dill leaves were investigated. In order to evaluate antioxidant activities of all extracts, different antioxidant tests were used, such as total antioxidant activity by ferric thiocyanate method, reducing power, DPPH (1,1-diphenyl-2-picryl-hydrazyl) free radical scavenging, hydrogen peroxide scavenging, and ferrous ions chelating activities. The content of phenolic compounds was also determined to be the gallic acid equivalent. Among the three extracts, the water extract of dill leaf showed the most potent antioxidative capacity in each assay, showing 79.66% (at 1 mg/mL) in the DPPH• radical scavenging activity, 63% (at 800 μg/mL) in the metal chelating effect, 60% (at 400 μg/mL) in the H2O2 scavenging activity, and 0.61 absorbance (at 1 mg/mL) in the reducing power.

Conversion of sunflower oil to biodiesel by alcoholysis using immobilized lipase.

Transesterification reaction was performed using sunflower oil and short-chain alcohol by immobilized lipases in organic solvents. The fatty acid ester, which is the product of this reaction, can be used as a diesel fuel that does not produce sulfur oxide and minimize the soot particulate. Immobilized porcine pancreatic lipase (PPL) and Candida rugosa lipase (CRL) showed the satisfactory activity in these reactions. Immobilization of lipases was carried out using inorganic absorbance Celit 545 particle as a carrier. Organic solvent like hexane in reactions was required when methanol and ethanol were used as alcoholic substrate. The reaction could be performed in absence of solvent when 1-propanol and 1-butanol were used as short-chain alcohol. The activities of immobilized lipases were highly increased in comparison with free lipases because its activity sites became more effective. Immobilized enzyme could be repeatedly used without difficult method of separation and the decrease in its activity was not largely observed.

Comparison of biodiesel productivities of different vegetable oils by acidic catalysis.

Biodiesel has become a subject which increasingly attracts worldwide attention because of its environmental benefits, biodegradability and renewability. Biodiesel production typically involves the transesterification of a triglyceride feedstock with methanol or other short-chain alcohols. This paper presents a study of transesterification of various vegetable oils, sunflower, safflower, canola, soybean, olive, corn, hazelnut and waste sunflower oils, with the acidic catalyst. Under laboratory conditions, fatty acid methyl esters (FAME) were prepared by using methanol in the presence of 1.85% hydrochloric acid at 100 °C for 1 h and 25 °C for 3 h. The analyses of biodiesel were carried out by gas chromatography and thin layer chromatography. Also, biodiesel productivities (%) were determined on basis of the ratio of ester to oil content (w/w). The biodiesel productivities for all oils were found to be about 80% and about 90% at 25 and 100 °C, respectively. Also, the results showed that the yield of biodiesel depended on temperature for some oils, including canola, sunflower, safflower oils, but it was not found significant differences among all of the oil types on biodiesel productivities.

Production of ricinoleic acid from castor oil by immobilised lipases.

Abstract Porcine pancreatic lipase (PPL), Candida rugosa lipase (CRL), and Castor bean lipase (CBL) were immobilized on celite by deposition from aqueous solution by the addition of hexane. Lipolytic performance of free and immobilized lipases were compared and optimizations of lipolytic enzymatic reactions conditions were performed by free and immobilized derivatives using olive oil as substrate. Afterwards, the influence on lipolysis of castor oil of free lipases and immobilized lipase derivatives have been studied in the case of production of ricinoleic acid. All of the lipases performances were compared and enzyme derivative was selected to be very effective on the production of ricinoleic acid by lipolysis reaction. Various reaction parameters affecting the production of ricinoleic acid were investigated with selected the enzyme derivative. The maximum ricinoleic acid yield was observed at pH 7–8, 50°C, for 3 hours of reaction period with immobilized 1,3-specific PPL on celite. The kinetic constants Km and Vmax were calculated as 1.6 × 10−4 mM and 22.2 mM from a Lineweaver–Burk plot with the same enzyme derivative. To investigate the operational stability of the lipase, the three step lipolysis process was repeated by transferring the immobilized lipase to a substrate mixture. As a result, the percentange of conversion after usage decreased markedly.

A new multienzyme-type biosensor for triglyceride determination

ABSTRACT An amperometric multienzyme biosensor for determination of triglycerides (TGs) was constructed by mounting three gelatin membrane-bound enzymes on a glassy carbon electrode (working electrode), then connecting it to electrometer along with an Ag/AgCl reference electrode and a Pt auxiliary electrode. Characterization and optimization of the multienzyme biosensor, which is prepared with glycerol kinase (GK) (E.C.2.7.1.30), glycerol-3-phosphate oxidase (GPO) (EC 1.1.3.21), and lipase (EC 3.1.1.3), were studied. In the optimization studies for the bioactive layer components of the prepared biosensor, the optimum amounts of gelatin, bovine serum albumin (BSA), and glutaraldehyde was calculated as 1 mg/cm2, 1 mg/cm2, and 2.5%, respectively. Optimum pH and temperature of the reaction of biosensor were determined as 7.0 and 40°C, respectively. Linear range of triolein for the biosensor was found from the calibration curve between several substrate concentration and Δ Current. After optimization and characterization of the biosensor, its operationability in triglycerides was also tested.

Preparation and properties of lipases immobilized on different supports

Porcine pancreatic lipase and Candida cylindracea lipase were immobilized on Celite and Amberlite IRA-938. Activities and stabilities of immobilized lipases were investigated. The immobilized lipase derivatives on Celite exhibited grater residual activity and more resistance to thermal inactivation than their immobilized counterpart on Amberlite IRA-938. The apparent optimum temperatures of the immobilized lipases were 7–10°C higher than that of the free enzymes. The native lipase and lipases immobilized on Celite showed same behaviors of pH dependence. But the pH optimum values for lipases immobilized on Amberlite IRA-938 were shifted to the acidic region relative to that of free enzymes. The stabilities of free and immobilized lipases were also investigated.

Total phenolic content, antiradical and antioxidant activities of wild and cultivated Rumex acetosella L. extracts

Edible greens, especially wild greens, play an important role in traditional diets and are rich in phenols and other compounds. The purpose of this study was to investigate total phenolic content (TPC) and antioxidant activities of ethanolic extracts from wild and cultivated Rumex acetosella L. The wild sheep sorrel extract inhibited lipid peroxidation and 1,1-diphenyl-2-picrylhydrazyl radical with EC50 values of 0.02 and 3.67 mg ml− 1; however, the EC50 values for cultivated sheep sorrel extract were 0.76 and 21.94 mg ml− 1. In the reducing power assay, the values of measured absorbance were 0.723 and 0.430 for wild and cultivated extracts, respectively, at 1 mg ml− 1 concentration. The chelating of ferrous ions by the wild and cultivated sheep sorrel was determined as 59.4% and 56.2%, respectively, at 1 mg ml− 1 concentration. TPC of wild and cultivated sheep sorrel was found to be 69.21 ± 8.5 and 57.57 ± 1.8 mg gallic acid equiv. g− 1 extract, respectively. There is a positive correlation between phenolic content and antioxidant assays. The results obtained in this study indicate that wild R. acetosella could be an important dietary source because of its good antioxidant properties.

An Assessment of In Vitro Antioxidant Activities of Different Extracts from Papaver rhoeas L. Leaves

Corn poppy (Papaver rhoeas L.) leaf has been extensively used as garniture in salads and drugs in folk medicine. In this study, the possible antioxidant properties of water (WE), ethanol (EE), and acetone (AE) extracts of corn poppy leaves were investigated using different antioxidant tests, including total antioxidant activity in linoleic acid system, DPPH• scavenging activity, reducing power, chelation activity, and hydrogen peroxide scavenging activity. In addition, the amount of total phenolics was also determined. Total antioxidant activities of all extracts were greater than 85% at 400 μg/mL concentration. The scavenging effects of WE and EE on DPPH• radical were found to be 88.46 ± 0.08% and 86.81 ± 0.37% at 800 μg/mL concentration, respectively, which was comparable to standard antioxidants, such as BHA and α-TP. The reducing power of extracts was in the order of WE > EE > AE. The percentage of metal chelating activity of 800 μg/mL concentration of WE was found to be 79.51 ± 4.05%. Our results indicated that the leaves of Papaver rhoeas L. showed the potential to be used as a natural antioxidant.