Total Antioxidant Activity Of Extracts Research Articles

PROSPECTS FOR USING ASTRAGALUS ONOBRYCHIS AS A SOURCE OF NATURAL ANTIOXIDANTS

The predominance of synthetic and genetically modified foods in the diet of a modern person often leads to disruption of natural metabolic processes and the accumulation of toxic free radicals in the body, which provokes the development of various diseases. Natural antioxidants from medicinal plants can help maintain health and stop the processes of peroxidation. In our opinion, Аstragalus onobrychis can become a promising source of natural antioxidants. The aim of this study was to establish the antioxidant activity in extracts from the herb Astragalus onobrychis. In order to obtain objective and reliable results during our research, we used two methods: the method of titrimetry and spectrophotometry of free radicals. The titrimetric method is based on the chemical interaction between an oxidizing agent (potassium permanganate) and natural antioxidants present in extracts from plant raw materials, since they exhibit the properties of reducing agents. The spectrophotometric method makes it possible to assess the value of antioxidant activity and the duration of the reaction by assessing the interaction of 2,2-diphenyl-1-picrylhydrazil with plant antioxidants. To establish the relationship between the antioxidant activity and the presence of phenolic compounds in the plant, the content of flavonoids and hydroxycinnamic acids in the herb Astragalus onobrychis was determined. As a result of the studies, the total antioxidant activity of extracts from the herb Astragalus onobrychis was established and it was revealed that its value depends on the type of extractant used, since this factor is associated with the content of various groups of natural antioxidants in the extraction. The data obtained indicate the prospects of using the herb Astragalus onobrychis as a source of natural antioxidants.

Comparative antioxidant capacity of plant leaves and herbs with their antioxidative potential in meat system under accelerated oxidation conditions

This study evaluated the comparative antioxidant effects of nine leaves extracts (pomegranate, PL; citrus, CL; kinnow, KL; mango, ML; guava, GL; peppermint, PM; oregano, OL; rosemary, RM; thyme, TL) in the meat system (MS) formulated with a healthier oil consisted of high level of polyunsaturated fatty acids. Total phenolic content of the extracts varied from 10.1 ± 1.44 to 98.8 ± 2.15 mg TAE/g; whereas, total flavonoid content varied from 1.6 ± 0.16 to 64.8 ± 0.41 mg CE/g. The DPPH scavenging activity of the extracts varied from 29.8 ± 0.87 to 58.5 ± 1.57% while BHT showed 77.1 ± 1.57% scavenging activity. Total antioxidant activity of extracts varied from 0.91 ± 0.14 to 3.90 ± 0.16 while the activity of BHT was 3.06 ± 0.14. The descending order for the antioxidant potential of the extracts (prepared at 70 °C) in the meat system was MS-GL70 = MS-PL70 = MS-BHT > MS-ML70 > MS-RM70 = MS-TL70 > MS-KL70 = MS-PM70 > MS-control. The addition of KL extract exerted negative effects (P < 0.05) on the color attributes. The addition of ML extracts increased in the emulsion stability (total expressible fluid % and expressible fat %). Hence, GL, PL, and ML can be considered as a good source of natural antioxidants for enhancing the oxidative stability of meat systems without affecting other technological properties.

THE STUDY OF ANTIOXIDANT ACTIVITY OF THE HERB ASTRAGALUS GLYCYPHYLLUS L

Topicality. In the process of originating and development of many diseases, an important role belongs to free radicals, which trigger chain reactions leading to damage of cells and tissues. The natural antioxidants can help to neutralize free radicals, among which phenolic compounds are the most active. The presence of these groups of biologically active substances in the herb Astragalus glycyphyllus L. suggests the presence of antioxidant activity in the phyto-complexes of the studied plant. The purpose of this research was to study the antioxidant activity of extracts from the herb Astragalus glycyphyllus L. Materials and methods. The object of the study was the air-dry herb Astragalus glycyphyllus L. harvested in the period of mass flowering. To obtain the most reliable results of the study, the investugation of the antioxidant activity of extracts from the herb Astragalus glycyphyllus L. was carried out by two met hods: by the method based on the chemical reaction between potassium permanganate and regenerating biologically active substances contained in extracts from the studied plant and by spectrophotometry of free radicals based on the reaction interactions of 2,2-diphenyl-1-picrylhydrazyl with antioxidants contained in plant raw materials. To establish the dependence between the antioxidant activity and the presence of phenolic compounds in the plant, the content of flavonoids and hydroxycinnamic acids in Astragalus glycyphyllus L. was determined. Results. It was found that all the studied extracts from the herb Astragalus glycyphyllus L. have antioxidant activity, but their values are different depending on the used extractant. In this case, a consistent pattern is observed between the content in the extraction of phenolic compounds (hydroxycinnamic acids and flavonoids) and the magnitude of antioxidant activity. Conclusions. As a result of the conducted research, the total antioxidant activity of extracts from the herb Astragalus glycyphyllus L. was established. Its value was found to be related to the content of phenolic compounds in the plant by a positive correlation. The obtained data indicate the promising use of the herb Astragalus glycyphyllus L. as a source of natural antioxidants. · Keywords: Astragalus glycyphyllus L.; antioxidant activity; flavonoids; hydroxycinnamic acids; free radicals.

Evaluation of antioxidant and antibacterial capacity of green microalgae Scenedesmus subspicatus.

Microalgae are considered one of the most promising raw materials for the development of high value products for pharmaceuticals, nutraceuticals, and cosmetic industries, as well as being potential sources of protein, vitamins, and minerals for human consumption. Hence, the present research focuses extraction of antioxidant and antimicrobial compounds from Scenedesmus subspicatus using solvents of different polarities. Different solvents such as ethanol, methanol, butanol, acetone, dimethyl sulfoxide, and water were used to extract compounds from the green microalgae S. subspicatus and then they were examined for phytochemical screening, antioxidant activity, and antimicrobial properties. Invitro free radical quenching and total antioxidant activity of extracts were investigated with 1,1-diphenyl-2-picryl hydrazyl and compared with catequin and gallic acid as positive controls. The antimicrobial activity was evaluated in gram-negative and gram-positive bacteria. Aqueous extracts and dimethyl sulfoxide presented better performance in phytochemical analysis. This result showed consistency in the sequential tests. The antioxidant activity was also better using the two solvents cited above. The extracts acetone, water, and dimethyl sulfoxide showed ability to inhibit the growth of Bacillus subtilis. However, only dimethyl sulfoxide inhibited the growth of Klebsiella pneumoniae and Escherichia coli. Use of the aqueous extract, proven its effectiveness, is an economic protocol and avoids the use of toxic substances.

Approaches to the determination of antioxidant activity of extracts from bee bread and safflower leaves and flowers

The main objective of this study was to develop approaches for the determination of total antioxidant activity of natural products (bee bread and safflower extracts) using DPPH radical scavenging assay. Considering that analytical procedures and results related to this assay and reported by many authors are significally differed between each other and depend on many factors (the nature of tested extracts, the nature of solvents for extraction, a reaction time of DPPH with a sample, DPPH solvents and concentration, ratio between DPPH and an extract, etc.), the methodology of the evaluation of antioxidant capacity of different origin extracts by DPPH radical scavenging assay was developed. Ascorbic acid (AA) was used as standard antioxidant and the correlation between the percentage of DPPH scavenging and AA concentration was determined at two different initial absorbances of DPPH solution. Average concentration of AA which inhibited 50% of DPPH radicals (IC50) was equal to 156.0 - 171.26 µg.mL-1. The reaction kinetics of DPPH inhibition by bee bread and safflower extracts was described by the curves of the dependence of the total antioxidant activity on time with squared correlation coefficients (R2) in the range of 0.89 - 0.98. The reaction times for these extracts were from 40 to 70 min at the correct ratio of volumes between the tested extracts and a DPPH solution. These studies demonstrated that the extracts obtained from bee bread of 2016 year of pollen collection had significantly higher the total antioxidant activity compared with the extracts of bee bread of pollen collection of 2015 considering the ratio of bee bread and the solvent in the extracts and volume of the extract for the procedure. This fact is explained not only botanical origin bun also the time of the storage of bee bread before the preparation of extracts. There was not found significant differences in the total antioxidant activity of extracts from flowers of safflower sown in fall and in spring. Antioxidant activity of the extracts from leaves of spring sown safflower was higher compared with the total antioxidant activity of the extracts from fall sown plants. Ascorbic acid equivalents of the tested extracts could be ranged as follows: bee bread of 2016 pollen collection &gt;bee bread of 2015 pollen collection &gt;leaves of safflower spring sown &gt;flowers of safflower spring sown &gt;flowers of safflower fall sown &gt;leaves of safflower fall sown.

Study of Antioxidant Activity of Biologically Active Compounds Isolated from Green Vegetables by Coupled Analytical Techniques

This study was carried out to determine the total antioxidant activity of selected green vegetables like kale and spinach. The antioxidant activity was expressed in radical scavenging activity (RSA). The generation of the DPPH· (1,1-diphenyl-2-picrylhydrazyl) free radical forms the basis of one of the spectrophotometric methods that has been applied to the measurement of the total antioxidant activity of extracts and solutions of pure substances. Among examined vegetables, spinach showed the highest total antioxidant activity. RSA values for samples of frozen spinach varied from 16.2% to 42.6%, but RSA for fresh spinach did not exceed 19.8%. Kale extracts were obtained by use of supercritical fluid extraction. The highest antioxidant activity was found for the first fraction of extracts, and it was 14.2% (for fraction obtained at pressure 258 bar and 5% methanol addition). Afterwards, lutein belonging to carotenoid group was determined in plant extracts by means of HPLC–UV-VIS. The concentration values of lutein ranged between 0.43 and 0.88 mg/g for three frozen spinach samples and 0.83 mg/g for fresh spinach. Lutein, has also antioxidant properties; therefore, RSA was determined for the standard solutions of lutein. However, the influence of lutein on the RSA values of spinach and kale is relatively low. Spinach, more than other analysed plants had an exceptionally high total polyphenol and flavonoid content.

Antioxidant properties of extracts from fermented and cooked seeds of Polish cultivars of Lathyrus sativus

Antiradical and total antioxidant activities of extracts from raw, prepared for inoculation, fermented (tempeh) and cooked seeds of grass pea (Lathyrus sativus Krab and Derek cultivars) were measured. Tempeh fermentation with Rhizopus oligosporus resulted in higher scavenging activity towards DPPH and ABTS+ radicals which correlated well with the content of total phenols. In Derek cultivar, fermentation caused a significant inhibition of linoleic acid oxidation by methanol extracts. In buffer extracts the highest TAA values were observed in raw seeds. Cooking of seeds lowered RSA values as compared to fermentation, especially for the DPPH assay. Methanol and buffer extracts from cooked seeds showed prooxidant activity towards linoleic acid.

Are whole extracts and purified glucosinolates from cruciferous vegetables antioxidants?

Fruits and vegetables contain several classes of compounds that can potentially contribute to antioxidant activity, including vitamins, simple and complex phenolics, sulphur-containing compounds and glucosinolates. The glucosinolates are found in high concentration in many cruciferous vegetables, and it is well established that their breakdown products induce endogenous antioxidant defences such as quinone reductase and glutathione S-transferase in cells and in vivo. Despite the anticarcinogenic effect of these compounds in animal models, the direct antioxidant properties of this class of compounds have not been systematically studied. We therefore examined the free radical-scavenging properties of representative extracts and of purified glucosinolates from cruciferous vegetables, by measuring their effect on ascorbate- or NADPH/iron-induced peroxidation of human liver microsomes, ascorbate/iron-induced peroxidation on phospholipid liposomes, iron chelation and hydroxyl radical scavenging using the deoxyribose assay, total antioxidant potential using ABTS (2,2'-azinobis(3-ethyl-benzothiazoline-6-sulphonate)) and the bleomycin assay. Most of the extracts from cruciferous vegetables exhibited some antioxidant properties, although extracts from cooked Brussels sprouts increased the rate of microsomal lipid peroxidation. The effects in these assays were dependent upon processing and species of crucifer, and the glucosinolate content appeared to play a minor role in these effects, since purified glucosinolates exhibited only weak antioxidant properties. The total antioxidant activities of extracts from cooked and autolysed Brussels sprouts were identical within experimental error. This is probably due to the content of phenolics which is unaltered by autolysis, despite the differences between these samples in other assays especially NADPH-iron-induced lipid peroxidation of human liver microsomes. The results demonstrate that glucosinolates are unlikely to account for the direct antioxidant effects of extracts from cruciferous vegetables.