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In this study, two carotenoid antioxidants lutein and neoxanthin were investigated for their ability to prevent oxidatively induced DNA damage. A Chlamydomonas reinhardtii alga was used as the natural source of lutein and neoxanthin. Analysis using HPLC with Diode Array Detector (DAD) showed that lutein and neoxanthin were the most abundant carotenoids in the extract of C. reinhardtii. An analysis using GC–MS/MS was performed to measure the damage induced by Fenton reaction to DNA and to evaluate the ability of lutein, neoxanthin and C. reinhardtii extract to inhibit such damage. The results showed that lutein and neoxanthin have the ability to reduce oxidatively induced DNA base damage to less than half of its magnitude. Extract of C. reinhardtii inhibited about 76% of the damage in comparison to control sample. Neoxanthin in lower concentrations than those of lutein proved to be better inhibitor of oxidatively induced DNA damage.

Slx5, a subunit of a SUMO-targeted ubiquitin ligase (STUbL) in yeast, has been implicated in maintenance of genomic stability. SUMOylation is an important post-translational modification involved in the regulation of several important cellular processes and cellular response to various environmental stressors. Oxidative stress occurs when production of reactive oxygen species (ROS) exceeds the antioxidant defense capacity of the cell. Elevated ROS levels cause oxidative damage to important cellular macromolecules such as DNA, lipids, and proteins, which is associated with several diseases. Herein, we investigated the role of Slx5 in oxidative stress tolerance in Saccharomyces cerevisiae. We show that deletion of SLX5 increases survival of yeast cells in response to H2O2-induced oxidative stress in a cell cycle independent manner. Accumulation of intracellular ROS as well as DNA and lipid damages were reduced; expressions of antioxidant defense mechanism-related genes were increased in slx5Δ cells compared to wild type (WT) under oxidative stress. We also show that slx5Δ cells have increased intracellular ROS levels and oxidative damage to DNA and lipids compared to WT in the absence of oxidative stress. Thus, our data together suggest that an adaptive stress induced by SLX5 deletion increases tolerance to oxidative stress in slx5∆ cells.

Oxidation of DNA due to exposure to reactive oxygen species (ROS) is a major source of DNA damage. ROS induced damage to DNA plays an important role in some diseases such as various cancers, aging and neurodegenerative diseases. The detection of DNA oxidation products plays a major role in assessing the mutagenicity potential of specific exposure. The GC–MS/MS method was developed for the ultrasensitive determination of individual DNA damage products. The validation results revealed that the proposed method was reliable and sensitive. Multiple response surface methodology (MRSM) was used to optimize derivatization conditions of oxidatively DNA base damage products before GC–MS/MS analysis. The optimum derivatization conditions were determined as 40 min for derivatization time, 120 °C for derivatization temperature and 1.4 for BSTFA/pyridine ratio under nitrogen atmosphere. The effects of thymol, carvacrol and thymoquinone as antioxidants were investigated on oxidative DNA damage. The determination of the oxidatively induced DNA damage products was performed after adding DNA and antioxidants with different concentrations under oxidative stress. Eighteen DNA base damage products were analyzed simultaneously using GC–MS/MS. This study showed a significant decrease in the amount of DNA base damage products when the antioxidants were present in the medium.

Phenolic compounds have been studied elaborately for their efficacy to improve health and to protect against a wide variety of diseases. Herein this study, different analysis methods were implemented to evaluate the antioxidant properties of catechin and cyanidin using their standard substances and as they found in the grape seeds extracts. Total phenol contents were 107.39 ± 8.94 mg GAE/g dw of grape seeds for grape seed extract (GSE) and 218.32 ± 10.66 mg GAE/g dw of grape seeds for acid-hydrolyzed grape seed extract (AcGSE). The extracts were analyzed by HPLC-DAD system and the results showed the presence of catechin, gallic acid, chlorogenic acid and ellagic acid in the processed methanolic extract and cyanidin, gallic acid and ellagic acid in the processed acidified methanolic extract. The protective abilities of catechin and cyanidin were tested against the oxidation of DNA. The results showed that cyanidin has better protection of DNA against oxidation than catechin. GSE and AcGSE were revealed to inhibit the oxidatively induced DNA damage. GSE decreased about 57% of damage caused by the Fenton control sample. This study could show new aspects of the antioxidant profiles of cyanidin and catechin.

Oxidative stress is considered as one of the significant causes of DNA damage which in turn contributes to cell death through a series of intermediate processes such as cancer formation, mutation, and aging. Natural sources such as plant and fruit products have provided us with interesting substances of antioxidant activity that could be recruited in protecting the genetic materials of the cells. This study is an effort to discover some of those antioxidants effects in their standard and natural forms by performing an ultra sensitive determination of the products of DNA oxidation using GC-MS/MS. Experiments were used to determine the direct antioxidant activity of the substances contained in the tendrils of Vitis vinifera (var. alphonse) by extracting them and achieving Folin-Ciocalteau and CHROMAC analyses to determine the total phenolic content (TPC) and the antioxidant capacity of the extract, respectively; results revealed a phenolic content of 11.39 +/- 0.30 mg Gallic Acid Equivalent (GAE)/g of the plant's fresh weight (FW) by Folin-Ciocalteau and 8.17 +/- 0.49 mg Trolox Equivalent (TE)/g FW by CHROMAC assays. The qualitative analysis of the plant extract by HPLC-DAD technique revealed that two flavonoid glycosides namely rutin and isoquercitrin in addition to chlorogenic acid were contained in the extract. The determination of the DNA oxidation products was performed after putting DNA, rutin and isoquercitrin standard samples with different concentration, and the extract's sample under oxidative stress. Eighteen DNA oxidation products were traced using GC-MS/MS with ultra-sensitivity and the experiments proved a significant decrease in the concentration of the DNA oxidation products when the extract was used as a protectant against the oxidative stress. It is believed by conclusion that the extract of V. vinifera's (var. alphonse) tendrils has a good antioxidant activity; hence it is recommended to be used as a part of the daily healthy food list if possible.

The effects of ultrasonic-assisted extraction factors for the main phenolic compound (quercetin) from Hypericum perforatum L. were optimized using the Box-Behnken design (BBD) combined with response surface methodology. The BBD was employed to evaluate the effects of extraction temperature (30-70 degrees C), extraction time (20-80min), methanol concentration (20-80%, v/v), and HCl concentration (0.8-2.0M) on the content of one of the major phenolic compounds of quercetin. The extracts were analyzed by high performance liquid chromatography (HPLC). The major phenolic compounds of H. perforatum were isolated and the antioxidant capacity and total phenol content were determined in crude extract and fractions. The optimum conditions were determined as extraction temperature 67 degrees C, extraction time 67min, methanol concentration 77% (v/v), and HCl concentration 1.2M. The predicted content of quercetin was 10.81mg/g dried plant under the optimal conditions and the subsequent verification experiment with 11.09mg/g dried plant confirmed the validity of the predicted model. The isolated compounds were identified as quercetin, cyanidin, protocatechuic acid, and kaempferol.

The multivariate calibration methods—partial least squares (PLS), orthogonal signal correction and partial least squares (OSC-PLS)—were employed for the prediction of total antioxidant activities of four Prunella L. species. High-performance liquid chromatography (HPLC) and spectrophotometric approaches were used to determine the total antioxidant activity of the Prunella L. samples. Several preprocessing techniques such as smoothing and normalization were employed to extract the chemically relevant information from the data after alignment with correlation optimized warping. The importance of the preprocessing was investigated by calculating the root mean square error for the calibration set for the total antioxidant activity of Prunella L. samples. The models developed on the basis of the preprocessed data were able to predict the total antioxidant activity with a precision comparable to that of the reference 2,2-azino-di-(3-ethylbenzothialozine-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl methods. The OSC-PLS model seems preferable because of its predictive and describing abilities and good interpretability of the contribution of compounds to the total antioxidant activity. The contribution of individual phenolic compounds to the total antioxidant activity was identified by HPLC. Copyright © 2012 John Wiley & Sons, Ltd.

Microbial lipase from Thermomyces lanuginosus (formerly Humicola lanuginosa ) was immobilized by covalent binding on a novel microporous styrene–divinylbenzene polyglutaraldehyde copolymer (STY–DVB–PGA). The response surface methodology (RSM) was used to optimize the conditions for the maximum activity and to understand the significance and interaction of the factors affecting the specific activity of immobilized lipase. The central composite design was employed to evaluate the effects of enzyme concentration (4–16%, v/v), pH (6.0–8.0), buffer concentration (20–100 mM) and immobilization time (8–40 h) on the specific activity. The results indicated that enzyme concentration, pH and buffer concentration were the significant factors on the specific activity of immobilized lipase and quadratic polynomial equation was obtained for specific activity. The predicted specific activity was 8.78 μmol p -NP/mg enzyme min under the optimal conditions and the subsequent verification experiment with the specific activity of 8.41 μmol p -NP/mg enzyme min confirmed the validity of the predicted model. The lipase loading capacity was obtained as 5.71 mg/g support at the optimum conditions. Operational stability was determined with immobilized lipase and it indicated that a small enzyme deactivation (12%) occurred after being used repeatedly for 10 consecutive batches with each of 24 h. The effect of methanol and tert -butanol on the specific activity of immobilized lipase was investigated. The immobilized lipase was almost stable in tert -butanol (92%) whereas it lost most of its activity in methanol (80%) after 15 min incubation.

Response surface methodology was used to optimize experimental conditions for ultrasonic-assisted extraction of phenolic compounds from blackberry leaves. The Box-Behnken design (BBD) was employed for the optimization of extraction parameters in terms of total phenolics and antioxidant capacity. The optimal conditions for results of ABTS and CUPRAC were HCl concentration 0.41 and 0.45 M, methanol concentration 61 and 64% (v/v), extraction temperature 66 and 68 °C and extraction time 105 and 117 min, respectively. The experimental values agreed with those predicted values within a 95% confidence level, thus indicating the suitability of response surface methodology in optimizing the ultrasound-assisted extraction of phenolic compounds from blackberry leaves. The results showed that phenolic compounds present in blackberry leaves exhibited significant antioxidant properties. Seven phenolic compounds such as ellagic acid, caffeic acid, chlorogenic acid, quercetin, myricetin, kaempferol and kaempferol 3-β- d -glucopyranoside were determined in blackberry leaves by HPLC-DAD after extraction at optimum conditions.

Response surface methodology was used to optimise experimental conditions for ultrasonic-assisted extraction of phenolic compounds from Artemisia absinthium. The central composite design was employed, the extracts were characterised by the determination of total phenolic content and antioxidant capacity. The total phenolic contents of extracts were determined by Folin method and also total antioxidant capacities of extracts were determined by ABTS and CUPRAC methods. The phenolic compounds of A. absinthium at optimum extraction conditions were determined by HPLC-DAD. The optimum conditions were determined as HCl concentration between 0.41 and 0.44 mol/L, methanol volume between 55% and 59% (v/v), extraction temperature between 64 and 70 degrees C, extraction time between 101 and 107 min. The experimental values agreed with those predicted within a 95% confidence level, thus indicating the suitability of response surface methodology in optimising the ultrasound-assisted extraction of phenolic compounds from A. absinthium.

Horseradish Peroxidase (HRP) was immobilized by covalent binding onto glutaraldehyde cross-linked chitosan beads and these beads were used for determination of total phenolic content in Prunella L. species. Central composite design (CCD) was employed to optimize the conditions for the maximum HRP activity and to understand the significance and interaction of the factors affecting the activity of immobilized HRP. The results indicated that enzyme concentration and immobilization time were significant factors for the immobilization of HRP. The optimum conditions were determined as enzyme concentration 0.25 mg mL(-1), pH 8.0 and immobilization time 20h. The recovered activity was obtained as 81% after immobilization under optimal conditions. Total phenol content was determined in four Prunella L. species (Prunella vulgaris L., Prunella laciniata (L.) L., Prunella orientalis Bornm., Prunella grandiflora L.) extracted using methanol, water and methanol/water (4 : 1, v/v). The enzymatic method is based on the spectrophometric measurement of the final quinone-imine colored product, absorbing at 510 nm, by HRP oxidation in presence of hydrogen peroxide. The results were compared with those obtained by applying the Folin method. The highest total phenol content was obtained with the methanol/water (4 : 1, v/v) extract of Prunella vulgaris L. by immobilized HRP method (63.75 mg gallic acid equivalent (GAE) per g dried plant). Operational stability was determined with immobilized HRP and it indicated that a small enzyme deactivation (15%) occurred after 10 consecutive uses.