Lutfiye Ekici

RP-HPLC–DAD analysis of phenolic compounds in pomace extracts from five grape cultivars: Evaluation of their antioxidant, antiradical and antifungal activities in orange and apple juices

Phenolic compounds, related to antioxidative and antifungal properties of ethanolic extracts from five commercial grape cultivars (three red and two white) grown in Turkey were determined. A reversed-phase high performance liquid chromatography (RP-HPLC) procedure was developed, and a total 18 different phenolic compounds were identified. Total phenolic contents of the extracts were determined using Folin-Ciocalteau method. Antioxidant activities of the extracts were evaluated by using DPPH radical scavenging and phosphomolybdenum methods. All extracts exhibited strong antioxidant and antiradical activity. Phenolic compounds and antioxidant activities of the extracts were variety dependent. Antifungal activities of the pomaces and extracts were screened by both in vitro agar-well diffusion assay and antifungal activity in apple and orange juices in situ using Zygosaccharomyces rouxii and Z. bailii. Antifungal activities revealed that the pomaces and extracts of Gamay and Kalecik karasi could be more effective antifungal agents than those of Emir, Narince and Okuzgozu grape cultivars.

Pre-heating and polyphenol oxidase inhibition impact on extraction of purple sweet potato anthocyanins

Purple sweet potatoes (PSP) have been used as a natural food colorant with high acylated anthocyanins concentrations. Commercially extracting pigments from PSP can be challenging due to firm texture and high polyphenol oxidase (PPO) content. These studies evaluated hot water immersions (30, 50, 70, and 90°C for 10 min) as pre-heating treatments and addition of PPO inhibitors (citric acid, oxalic acid, and sodium borate) to aqueous extraction solutions to aid pigment recovery. Predominant PSP anthocyanins included acylated cyanidin or peonidin derivatives. Non-pigmented cinnamates acted as oxidase substrates and induced co-oxidation reactions with anthocyanins. Pre-heating PSP significantly increased polyphenolic yields in a temperature-dependent manner, consistent with tissue softening and PPO inactivation. The use of solvent modifiers in the extraction solution associated with heat helped minimize enzyme action and increased polyphenolic recovery. Minimizing the impact of PPO with heat was critical to the extraction and recovery of PSP anthocyanins, suitable for food use.

Effects of Temperature, Time, and pH on the Stability of Anthocyanin Extracts: Prediction of Total Anthocyanin Content Using Nonlinear Models

In this study, different anthocyanin sources including grape skin, black carrot, and red cabbage were used to determine the effect of thermal treatment, different acidity levels, and time on the anthocyanin content and degradation. The total anthocyanin contents were modeled by neuro fuzzy inference system (ANFIS) and artificial neural network (ANN) models. The red cabbage anthocyanin stabilities were higher than others. The anthocyanins degraded more rapidly at higher temperatures. The anthocyanin contents of samples decreased with the increase of pH from 3 to 7. Comparison of the models showed that the ANFIS model performed better than the ANN model for the estimation of total anthocyanin content in all samples. The lowest root mean square error (0.0457) and highest R2 (0.9942) values were obtained for red cabbage and grape skin in the validation period with the ANFIS model, respectively. This study showed that both models can be utilized efficiently for the prediction of total anthocyanin content affected by temperature, time, and pH.

Evaluation of the Phenolic Content, Antiradical, Antioxidant, and Antimicrobial Activity of Different Floral Sources of Honey

Thirty-five honeys were evaluated for total phenolic content by Folin-Ciocalteu method, for potential antioxidant activity using phosphomolibdenum assay and by the 1,1-diphenyl-2-picrylhydrazyl method for antiradical activity. The antimicrobial activity was studied by the agar diffusion method, using 12 bacteria and 2 yeasts. The means of the total phenolic contents of chestnut, honeydew, multifloral, thyme, and astragalus were 47 ± 18, 24.2 ± 0.6, 14 ± 11, 11 ± 6, and 9 ± 7 mg/100 g honey as gallic acid equivalent, respectively. The lowest antioxidant activity was observed in honeydew 70 ± 5 mg ascorbic acid equivalent/g honey while the highest content was observed in astragalus honey 86 ± 16 mg ascorbic acid equivalent/g honey. Correlation between the phenolic content and antioxidant activity were found to be statistically significant. Chestnut honeys (n = 5) exhibited maximum free radical scavenging activity with an average 68 ± 9%. The honey samples showed the highest antimicrobial activity against some microorganisms, especially Escherichia coli O157:H7, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Proteus mirabilis. On the other side, Aeromonas hydrophila, Bacillus subtilis, and E. coli were the most resistant microorganisms. The results revealed that the Turkish honeys studied proved to be a good source of antioxidant and antimicrobial agents that might serve to protect human health.

Cytotoxic and bioactive properties of different color tulip flowers and degradation kinetic of tulip flower anthocyanins.

This study was conducted to determine the potential use of anthocyanin-based extracts (ABEs) of wasted tulip flowers as food/drug colorants. For this aim, wasted tulip flowers were samples and analyzed for their bioactive properties and cytotoxicity. Total phenolic contents of the extracts of the claret red (126.55 mg of gallic acid equivalent (GAE)/g dry extract) and orange-red (113.76 mg GAE/g dry extract) flowers were the higher than those of the other tulip flowers. Total anthocyanin levels of the violet, orange-red, claret red and pink tulip flower extracts were determined as 265.04, 236.49, 839.08 and 404.45 mg pelargonidin 3-glucoside/kg dry extract, respectively and these levels were higher than those of the other flowers. The extracts were more effective for the inhibition of Listeria monocytogenes, Staphylococcus aureus and Yersinia enterocolitica compared to other tested bacteria. Additionally, the cytotoxic effects of five different tulip flower extracts on human breast adenocarcinoma (MCF-7) cell line were investigated. The results showed that the orange red, pink and violet extracts had no cytotoxic activity against MCF-7 cell lines while yellow and claret red extracts appeared to be toxic for the cells. Overall, the extracts of tulip flowers with different colors possess remarkable bioactive and cytotoxic properties.

Antimicrobial and antioxidant activities of Senecio species growing in the Black Sea region, Turkey

Abstract Total phenolic contents, antioxidant and antimicrobial activities of methanol extracts of six Senecio species growing in the Black Sea region of Turkey (S. pandurifolius, S. trapezuntinus, S. integrifolius subsp. aucheri, S. hypochionaeus var. argaeus, S. hypochionaeus var. ilkasiensis and S. orentii) are investigated. The total phenolic content is analysed using Folin- Ciocalteus reagent of the methanol extracts and varies from 19.54 to 81.78 mg GAE/g dry extract. The methanol extracts of the studied species possess antioxidant properties in the range of 70.07–165.21 mg AAE/g dry extract in phosphomolybde- num assay. S. hypochionaeus var. ilkasiensis extract shows maximum activity with an IC50 of 15.94 μg/ml in DPPH free radical scavenging assay. All of the Senecio methanol extracts show similar antimicrobial activities against microorganisms tested by agar diffusion methods. Klebsiella pneumoniae is the most sensitive microorganism to the all extracts examined while Escherichia coli and Candida albicans are the most resistant one.

Natural food colorants and bioactive extracts from some edible flowers

Consumers’ interest in natural coloring has also been growing in parallel with their consciousness of food-health relationship. Anthocyanin based colorings bear antioxidative features renders this group of colorings more attractive. In this research, heat stabilizations and some bioactive properties of anthocyanin-based extracts (ABE) obtained from corn poppy, tulip, rose and roselle, were determined. While the greatest amount of phenolic substance is determined in the tulip (113.76 mg gallic acid equivalents (GAE) g -1 dry extract), the greatest amount of anthocyanin is in the corn poppy (405.22 mg cy-3-glucoside g -1 dry extract). Of the extracts, the corn poppy, with a level 55.85 μg mL -1 , has been determined to have the highest antiradical capacity, and the tulip, with a level of 63.44 mg of ascorbic acid equivalent (AAE) g -1 dry extract has been determined to have the highest antioxidant activity. While there has been no antimicrobial effect of corn poppy extract observed on any microorganism, roselle extracts have been found to display high antimicrobial activity. Heat stability of ABEs were investigated in buffer solution pH 3.5. The flowers have high bioactive properties. There are studies planned on the use as coloring in various nutrients of the flower extracts with high bioactivity.

Determination of phenolic content, antiradical, antioxidant and antimicrobial activities of Turkish pine honey

Pine (Pinus brutia Ten.) honey obtained from Mugla (n=12) and Marmaris (n=8) in the southwest of Turkey were evaluated for total phenolic content by the Folin-Ciocalteu method, for potential antioxidant capacity using phosphomolybdenum assay and by the 1,1-diphenyl-2-picrylhydrazyl method for antiradical activity. The results of the study showed that total phenolic content of honey obtained from Mugla and Marmaris ranged from 62.01 and 68.78 mg/100 g honey as gallic acid equivalent, respectively. The antioxidant capacity of honey obtained from Mugla and Marmaris were 16.82 and 22.16 mg ascorbic acid equivalent/g honey, respectively. The antiradical activity of honey samples were assayed in vitro by measuring the inhibition of the scavenging activities of pine honey collected from Mugla and Marmaris which were found to be 44.05 and 57.49%, respectively. Pine honey did not show antimicrobial activity at 5, 10 and 25% concentrations. The samples showed their highest antimicrobial activity against some microo...