Izabela Biskup

Antioxidant activity of selected phenols estimated by ABTS and FRAP methods.

INTRODUCTION Phenols are the most abundant compounds in nature. They are strong antioxidants. Too high level of free radicals leads to cell and tissue damage, which may cause asthma, Alzheimer disease, cancers, etc. Taking phenolics with the diet as supplements or natural medicines is important for homeostasis of the organism. MATERIALS AND METHODS The ten most popular water soluble phenols were chosen for the experiment to investigate their antioxidant properties using ABTS radical scavenging capacity assay and ferric reducing antioxidant potential (FRAP) assay. RESULTS AND DISCUSSION Antioxidant properties of selected phenols in the ABTS test expressed as IC50 ranged from 4.332 μM to 852.713 μM (for gallic acid and 4- hydroxyphenylacetic acid respectively). Antioxidant properties in the FRAP test are expressed as μmol Fe2+/ml. All examined phenols reduced ferric ions at concentration 1.00 x 10-3 mg/ml. Both methods are very useful for determination of antioxidant capacity of water soluble phenols.

Plasma alkylresorcinols, biomarkers of whole-grain wheat and rye intake, and risk of type 2 diabetes in Scandinavian men and women

BACKGROUND Studies that use dietary biomarkers to investigate the association between whole-grain intake and the risk of developing type 2 diabetes (T2D) are lacking. OBJECTIVE We examined the association between plasma total alkylresorcinols and the alkylresorcinol C17:0-to-C21:0 ratio, biomarkers of whole-grain wheat and rye intake and relative whole-grain rye over whole-grain wheat intake, respectively, and the risk of T2D among Scandinavian men and women. DESIGN A nested case-control study was established within the Northern Sweden Health and Disease Study and the Danish Diet, Cancer and Health cohort. Alkylresorcinol concentrations and the ratios of C17:0 to C21:0 were determined in plasma samples from 931 case-control pairs. ORs for T2D were calculated for plasma total alkylresorcinol concentration or C17:0-to-C21:0 ratio in quartiles with the use of conditional logistic regression that was adjusted for potential confounders. Additional analyses with whole-grain wheat and rye intake estimated from food-frequency questionnaires (FFQs) as exposures were also performed. RESULTS The plasma total alkylresorcinol concentration was not associated with T2D risk (OR: 1.34; 95% CI: 0.95, 1.88) for the highest compared with the lowest quartiles in multivariable adjusted models. However, the C17:0-to-C21:0 ratio was associated with a lower diabetes risk (OR: 0.54; 95% CI: 0.37, 0.78). Analyses with whole-grain intake estimated from FFQs yielded similar results. CONCLUSIONS Total whole-grain wheat and rye intake, reflected by alkylresorcinols in plasma, was not associated with a lower risk of T2D in a population with high whole-grain intake. In contrast, the proportion of whole-grain rye to whole-grain wheat intake, indicated by the plasma C17:0-to-C21:0 ratio, was inversely associated with T2D. This suggests that whole-grain intake dominated by rye may be favorable for T2D prevention.

Total phenolic content and antioxidant capacity of polish apple ciders

The total phenolic content and antioxidant capacity of three apple ciders produced in Poland were examined. The total phenolic content was determined by the Folin-Ciocalteau method and results were expressed in gallic acid equivalents with range from 0.21±0.003 to 0.30±0.004 mg/ml and Trolox equivalents ranging 0.88±0.012 to 1.24±0.015 mg/ml. The antioxidant activity was estimated by two methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay with results expressed as EC50(ml/assay) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid method with results expressed as Trolox equivalent antioxidant capacity. The antioxidant properties of tested ciders were correlated with total phenolic content. Additionally, the correlation between 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid and 2,2-diphenyl-1-picrylhydrazyl radical scavenging methods was estimated.

In vitro evaluation of the antioxidant and antimicrobial activity of DIMBOA [2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one]

Abstract The aim of this study was to evaluate the in vitro antioxidant and antimicrobial properties of the natural cyclic hydroxamic acid: 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA). Antioxidant activity of the isolated DIMBOA was examined using DPPH, FRAP and ABTS tests. It was found that DIMBOA exhibits a potent free-radical scavenging activity and a weaker iron (III) ions reducing activity. Antimicrobial activity against selected G(+), G(–) bacterial strains and against yeasts-like reference strains of fungi was investigated using disk-diffusion method. It has been shown that DIMBOA possess growth inhibitory properties against many strains of studied bacteria and fungi, such as Staphylococcus aureus, Escherichia coli as well as against Saccharomyces cerevisiae. Graphical abstract

Fractionation of buckwheat seed phenolics and analysis of their antioxidant activity

Abstract Five fractions of phenolic compounds were obtained from the extract of common buckwheat seed (Fagopyrum esculentum Moench) using Sephadex LH-20 column chromatography with methanol as a mobile phase. The total phenolics content ranged from 19.8±1.5 (fraction I) to 164±2.2 mg (+)-catechin eq/g (fraction IV). The profiles of phenolic acids and flavonoids in the fractions were analysed using RP-HPLC-DAD. The antioxidant activity was tested as ABTS⋅+ and DPPH⋅ scavenging activity and capability to reduce the Fe(III)/2,4,6-Tris(2-pyridyl)-s-triazine complex to the ferrous form. Results were expressed as Trolox equivalent antioxidant capacity (TEAC), IC50 and ferric reducing antioxidant power (FRAP) values, respectively. The highest antioxidant activity was noted for fraction IV that was predominated by flavones. TEAC, IC50 and FRAP values were: 1.47±0.01 mmol Trolox eq/g, 0.058±0.003 mg/assay and 2.18±0.05 mmol Fe(II)/g, respectively. Rutin constituted 77.7% of the compounds identified in fraction III. The antiradical activity and reducing capability of this fraction were lower compared to fraction IV, but significantly higher than in fractions I and II. The main phenolic compounds of fractions I and II were phenolic acids (caffeic, 5-O-caffeoylquinic and p-coumaric). The antioxidant activity of fraction V was similar to that of fraction III.

The potential role of selected bioactive compounds from spelt and common wheat in glycemic control

Diet is an important lifestyle factor which influences peoples health and the prevention of chronic diseases such as type 2 diabetes. Cereal-based foods constitute the main component of the everyday diet worldwide. Old cereal species like spelt (Triticum spelta L.) are becoming more and more popular, especially in Europe. This review focuses on the role of bioactive compounds from spelt and their possible biological mechanisms of action in glycemic control. Spelt grain contains a high amount of dietary fiber, which can modulate postprandial glycemia. Other phytochemicals, such as phytic acid and alkylresorcinols, also contribute to controlling blood glucose levels, insulin sensitivity and hiperinsulinemia. Antioxidant compounds present in spelt grain may act as protection from negative outcomes of chronic hyperglycemia. In this paper the composition and beneficial properties of spelt are also compared with those of widely consumed cereals like common wheat (Triticum aestivum L.). The health benefits of whole grain as opposed to refined products are also discussed.