Evaluation of in vitro free radical scavenging potential of Streptomyces sp. AM-S1 culture filtrate

The present study was carried out to determine the free radical scavenging potential of culture filtrate of Streptomyces sp. AM-S1. Antioxidant activity of culture filtrate, lyophilized culture filtrate and ethyl acetate extract of Streptomyces sp. AM-S1 was determined by various in vitro assays such as ferric reducing power assay, phosphomolybdenum reduction, DPPH and ABTS radical scavenging activities. The results revealed that the culture filtrate of Streptomyces sp. AM-S1 effectively scavenged DPPH (IC50 90.2 μl/ml) and ABTS (IC50 13.2 μl/ml) radicals in a concentration dependent manner. In all the assays, ethyl acetate extract registered higher antioxidant activity when compared with the lyophilized culture filtrate (LCF). In addition, ethyl acetate extract (1123.4 μmole Fe(II)/mg extract) exhibited higher ferric reducing activity than the standard BHA (814.4 μmole Fe(II)/mg extract). Further works are needed on the isolation and identification of antioxidant molecules from the ethyl acetate extract of Streptomyces sp. AM-S1 culture filtrate.

Antioxidant Capacity of Selected Plant Extracts and Their Essential Oils

The main objective of this study was the screening of some selected aromatic plants very popular in Greece, with respect to their total phenolic content, antioxidant capacity, reducing activity, and oxidative stability. All plants were extracted with the conventional method, reflux with methanol. The essential oils of the plants were also analyzed for their antioxidant properties. The total phenolic content was determined by the Folin-Ciocalteu method using gallic acid as the standard, while the phenolic substances were identified and quantified by High Performance Liquid Chromatography (HPLC) coupled with a multi-wavelength ultraviolet-visible (UV-vis) detector. The antioxidant capacity of the plant extracts was measured by their ability to scavenge free radicals such as (a) DPPH (2,2-diphenyl-1-picrylhydrazyl) and, (b) ABTS (2,2′-azinobis-(3-ethylbenzothiaziline-6-sulfonate). The Folin-Ciocalteu method proved the existence of antioxidants in the aromatic plant extracts. Taking into account the results of the DPPH and ABTS methods, the free radical scavenging capacity was confirmed. Eventually, all plants exhibited low but noticeable protection levels against lipid oxidation, as determined by the Rancimat test.

Estimation of phytochemical content and antioxidant activity of some selected traditional Indian medicinal plants

The powder samples and methanol extract of 11 medicinal plants were subjected to analysis of proximate composition and measurement of antioxidant activity. Different parameters studied include phenolic contents, moisture, ash, crude fiber, fats and waxes. The assays employed were ferric reducing antioxidant power, trolox equivalent antioxidant capacity and scavenging effect on the 1,1-diphenyl-2-picrylhydrazyl free radical. Results obtained indicate that the antioxidant potential varied significantly from plant to plant. The total phenolic contents were determined spectrophotometrically using Folin-Ciocalteu reagent. Significant correlation is observed between ferric reducing antioxidant power and phenolic contents (R(2) = 0.96). These findings show that the polyphenolic constituents in the extracts are responsible for free radical scavenging capacity.

Influence of pressure cooking on antioxidant activity of wild (Ensete superbum) and commercial banana (Musa paradisiaca var. Monthan) unripe fruit and flower

Banana is a highly nutritious fruit crop consumed by many people's worldwide while endangered species are consumed by limited peoples and their health benefits are not explored. The unripe fruits and flowers of wild and commercial banana are consumed by peoples after cooking only. Hence, the present study was undertaken to evaluate and compare the effect of pressure cooking on antioxidant activity of wild and commercial banana species. The raw and processed samples were extracted with 70 % acetone. Except wild flower, thermal processing enhanced the content of phenolics, tannins, flavonoids, DPPH, ABTS, FRAP, hydroxyl and peroxidation activity than raw. Wild species presented higher phenolics, tannins, DPPH, ABTS and FRAP activity than commercial ones. Except few samples, wild species and commercial species exhibit similar activity in superoxide, hydroxyl and peroxidation activity. FRAP (r (2)  = 0.922; 0.977) and hydroxyl (r (2)  = 0.773; 0.744) activities were dependent on phenolics and tannin content whereas tannins may be responsible for DPPH scavenging activity (r (2)  = 0.745). Thermal processing enhanced the antioxidant activity might be due to the release of bound phenolics from cell wall and oxidation and polymerisation of compounds present in it. This wild species may be an alternative to commercial ones and will be valuable to consumers for protecting from chronic diseases.

Antioxidant activities of extract and fractions from receptaculum nelumbinis and related flavonol glycosides

The antioxidant activities of ethanolic crude extract (ECE) and its four different solvent sub-fractions (namely, petroleum ether fraction (PEF), ethyl acetate fraction (EAF), n-butanol fraction (BF) and the aqueous fraction (AF) from the receptacles of Nelumbo nucifera Gaertn. (Receptaculum Nelumbinis) were investigated using two in vitro antioxidant assays. BF showed the highest total phenolic content (607.6 mg/g gallic acid equivalents), total flavonoid content (862.7 mg/g rutin equivalents) and total proanthocyanidin content (331.0 mg/g catechin equivalents), accompanied with the highest antioxidant activity compared to other fractions through 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging assays. Five flavonol glycosides, namely hyperoside (1), isoquercitrin (2), quercetin-3-O-β-d-glucuronide (3), isorhamnetin-3-O-β-d-galactoside (4) and syringetin-3-O-β-d-glucoside (5) were isolated from the Receptaculum Nelumbinis. Compounds 2-5 were isolated for the first time from the Receptaculum Nelumbinis. The five isolated flavone glycosides, particularly compounds 1-3, demonstrated significant DPPH and ABTS radical scavenging activity, with IC(50) values of 8.9 ± 0.2, 5.2 ± 0.2, 7.5 ± 0.1 for DPPH and 114.2 ± 1.7, 112.8 ± 0.8, 172.5 ± 0.7 μg/mL for ABTS, respectively. These results suggest that Receptaculum Nelumbinis has strong antioxidant potential and may be potentially used as a safe and inexpensive bioactive source of natural antioxidants.

In vitro free radical scavenging and DNA damage protective property of Coriandrum sativum L. leaves extract

Coriandrum sativum L. (coriander), an everyday spice in the Indian kitchen is known to add flavor to the cuisine. It is an annual herb belonging to the Apiaceae (Umbellifera) family. The hydro-alcohol extract of Coriandrum sativum L. at the dose of 1 mg/ml was subjected to a series of in vitro assays viz. 2, 2'- diphenyl-1-picrylhydrazyl, lipid peroxidation by thiobarbituric acid, reducing power and nitric oxide (NO) radical scavenging in order to study its antioxidant efficacy in detail. The amount of flavonoids in 70% ethanol extract was found to be 44.5 μg and that of the total phenols was 133.74 μg gallic acid equivalents per mg extract. The extracts of the leaves showed metal chelating power, with IC50 values, 368.12 μg/ml where as that of standard EDTA was 26.7 μg/ml. The IC50 values for 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid radical scavenging was 222 μg/ml where as that of standard ascorbic acid was 22.6 μg/ml. The NO scavenging activity of the extract of the leaves showed IC50 value of 815.6 μg/ml; at the same time the standard BHA had 49.1 μg/ml. All the plant extracts provided DNA damage protection; however, the protection provided at the dose of 8 μg/ml was comparable to that of standard gallic acid. The Coriandrum sativum leaf extract was able to prevent in vitro lipid peroxidation with IC50 values; 589.6 μg/ml where as that of standard BHA was 16.3 μg/ml. Our results also showed significant ferric reducing power indicating the hydrogen donating ability of the extract. This study indicated the potential of the leaf extract as a source of natural antioxidants or nutraceuticals that could be of use in food industry with potential application to reduce oxidative stress in living system.

Advances in the analytical methods for determining the antioxidant properties of honey: a review

Free radicals and reactive oxygen species (ROS) have been implicated in contributing to the processes of aging and disease. In an effort to combat free radical activity, scientists are studying the effects of increasing individuals' antioxidant levels through diet and dietary supplements. Honey appears to act as an antioxidant in more ways than one. In the body, honey can mop up free radicals and contribute to better health. Various antioxidant activity methods have been used to measure and compare the antioxidant activity of honey. In recent years, DPPH (Diphenyl-1-picrylhydrazyl), FRAP (Ferric Reducing Antioxidant Power), ORAC (The Oxygen Radical Absorbance Capacity), ABTS [2, 2-azinobis (3ehtylbenzothiazoline-6-sulfonic acid) diamonium salt], TEAC [6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid (Trolox)-equivalent antioxidant capacity] assays have been used to evaluate antioxidant activity of honey. The antioxidant activity of honey is also measured by ascorbic acid content and different enzyme assays like Catalase (CAT), Glutathione Peroxidase (GPO), Superoxide Dismutase (SOD). Among the different methods available, methods that have been validated, standardized and widely reported are recommended.

New spectrophotometric method for determining nitrogen dioxide in air using 2,2-azino-bis(3-ethyl benzothiazoline)-6-sulfonic acid-diammonium salt and passive sampling

A new simple and highly sensitive spectrophotometric method for determining nitrogen dioxide in air was developed. The method is based on converting atmospheric nitrogen dioxide to nitrite ions within the IVL passive samplers used for samples collection. Acidifying nitrite ions with concentrated HCl produced the peroxynitrous acid oxidizing agent which was measured using 2, 2-azino-bis(3-ethyl benzothiazoline)-6-sulfonic acid-diammonium salt (ABTS) as reducing coloring agent. A parallel series of collected samples were measured for its nitrite content using a validated ion chromatographic method.The results obtained using both methods were compared in terms of their sensitivity and accuracy. Developed spectrophotometric method was shown to be one order of magnitude higher in sensitivity compared to the ion chromatographic method. Quantitation limits of 0.05 ppm and 0.55 μg/m(3) were obtained for nitrite ion and nitrogen dioxid, respectively. Standard deviations in the ranges of 0.05-0.59 and 0.63-7.92 with averages of 0.27 and 3.11 were obtained for determining nitrite and nitrogen dioxide, respectively.Student-t test revealed t-values less than 6.93 and 4.40 for nitrite ions and nitrogen dioxide, respectively. These values indicated insignificant difference between the averages of the newly developed method and the values obtained by ion chromatography at 95% confidence level.Compared to continuous monitoring techniques, the newly developed method has shown simple, accurate, sensitive, inexpensive and reliable for long term monitoring of nitrogen dioxide in ambient air.

In vitro antioxidant activity of extracts from the leaves of Felicia muricata thunb. An underutilized medicinal plant in the Eastern Cape Province, South Africa

Felicia muricata is a medicinal plant used for the management of different human and livestock diseases in the Eastern Cape Province of South Africa. The antioxidant potential of the leaves from this herb was investigated using its water, methanol, acetone and ethanol extracts. All the extracts were rich in phenols, proanthocyanidins and flavonols but low in flavonoids. The water extract exhibited low DPPH scavenging activity while the methanol, acetone and ethanol extracts showed higher activities. Again all the extracts showed high ABTS scavenging activity with a correlation between total phenolic content (R2 = 0.9965), DPPH (R2 = 0.982) and ABTS (R2 = 0.927). Traditionally, however, plant extracts are prepared with water as infusions, decoction and poultice. Our results have shown that both the water and ethanol extracts from Felicia muricata displayed strong antioxidant activity. Therefore, it would seem likely that both solvents were able to extract those compounds which are responsible for the antioxidant activity of F. muricata.

Efficient assay for total antioxidant capacity in human plasma using a 96-well microplate

In the present study, we tried to establish an efficient assay for total antioxidant capacity (TAC) in human plasma using a 96-well microplate. TAC was assessed using lag time by antioxidants against the myoglobin-induced oxidation of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) with hydrogen peroxide, and expressed as Trolox equivalent. The linearity of the calibration curve with Trolox was maintained with the Trolox concentration range from 2.5 µM to 25 µM (R² = 0.997). The assay was applied to the measurement of TAC in healthy human plasma. Coefficient of variation in intraday assay was 2.4%. Difference was not observed in interday assay. Plasma TAC of men ((569 ± 41) µM Trolox equivalent; n = 6) was higher than that of women ((430 ± 28) µM Trolox equivalent; n = 4). After the vegetable juice was drunk for 1 week, the increase in plasma TAC was observed in almost all the volunteers. In summary, we developed the efficient assay for plasma TAC using a 96-well microplate.

Characterisation of polyphenols and antioxidant properties of five lettuce varieties and escarole

Salad vegetables could be relevant as dietary sources of natural antioxidants. A better knowledge of their composition can be useful for understanding their potential bioavailability and biological activities. The antioxidant compounds, polyphenols and vitamin C, have been determined in five varieties of lettuce (iceberg, romaine, continental, red oak leaf, lollo rosso) and one variety of escarole (frissé). The polyphenol study by HPLC-DAD-MS/MS ESI allowed the identification of two compounds previously not reported in lettuce; quercetin and luteolin rhamnosyl-hexosides. Qualitative and quantitative differences were observed between the polyphenol profiles. Caffeic acid derivatives were the main phenolics in green varieties, while flavonols were detected in higher quantities in red varieties and escarole, and anthocyanins were only present in red-leafed varieties. The highest total phenolic content was observed in red-leafed varieties while the highest level of vitamin C was detected in the continental variety. The red varieties showed the highest antioxidant activity by all the methods assayed.