DPPH free radical-scavenging assay

Abstract Recently, we have investigated Aconitum cochleare Woroschin and obtained three new alkaloids cochleareine, acoleareine from the aerial parts of the plant and cochleareinine from the roots. Cochlearenine exhibited antioxidant activity against DPPH free radical scavenging assay. The cardio active effect of has also have been studied on isolated heart preparations. 

Antioxidant activity of petroleum ether, chloroform, ethyl acetate and methanol extracts of Usnea pictoides lichen was determined by DPPH free radical scavenging assay and ferric reducing assay (Pavithra et al. 2013). The scavenging potential of methanol extract was higher than other extracts, and also, in ferric reducing assay, methanol extract showed stronger reducing power than other extracts. 

The aqueous and ethyl acetate flower extracts rich in luteolin and luteolin-7-gluco-side exhibited antioxidant activity in the 2,2-iphenyl-l-picrylhydrazyl (DPPH) free radical scavenging assay as well as in the phosphatidylcholine liposome assay. Lower concentrations, however, had a pro-oxidant effect. 

Most stilbenoids possess antioxidant activities because they possess polyphenol functions in the molecules. Some of their beneficial effects, hepatoprotective action, cardiovascular protection, for instance, are in close relation to their antioxidant activities. Several models have been employed in the assay such as lipid peroxidation system, human low-density lipoprotein model, xanthine oxidase system and l,l-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging model, which is the most commonly used protocol. 

Alcoholic extracts of the roots and leaves of E. angustifolia, E. pallida, and E. purpurea exhibited comparable in vitro antioxidant activities in ABTS free radical scavenging assay, and the root extracts were also active in the lipid peroxidation inhibition assay.Methanolic extracts of freeze-dried roots of the three species act as in vitro antioxidants through the scavenging of DPPH and ABTS radicals, as well as by chelation of the copper ion (Cu Copper-catalyzed oxidation of human LDL was further demonstrated in vitro by different preparations from E. purpurea root containing alkamides, caffeoyl derivatives, and polysaccharides, as well as by pure caffeoyl derivatives. The antioxidant effect was synergistic and dose dependent. ... 

The antioxidant activity of the four phytochemicals isolated from rosemary were assayed in a DPPH free radical scavenge system. Carnosic acid, camosol and rosmarinic acid showed concentration-dependent scavenging ability. These phytochemicals were more potent than vitamin C and vitamin E. The 50% DPPH... 

Free radical scavenging activity was assessed using the DPPH (1, 1-di-phenyl-2-picrylhydrazyl) assay as described by Harbilas et al. [22] with incubation time increased to 65 min. Briefly, 250 tiL of 100 timol/L DPPH dissolved in methanol was added to 40 p.L of extract (tested at 5 concentrations) in a microplate well. A standard curve of ascorbic acid (positive control) was included as a reference and all data were blanked against a treatment with only methanol. Absorbance was read with a microplate reader at 517 nm. The inhibitory concentration for 50% scavenging (IC50) of each extract was calculated and compared to the IC50 of the ascorbic acid standard curve. 

A19. Atsumi, T., Iwakura, I., Kashiwagi, Y., Fujisawa, S., and Ueha, T., Free radical scavenging activity in the nonenzymatic fraction of human saliva A simple DPPH assay showing the effect of physical exercise. Antioxid. Redox Signal. 1, 537-546 (1999). 

DPPH (l,l-diphenyl-2-picryhydrazyl) is a purple-colored stable free radical that is reduced to the yellow-colored diphenylpicrylhydrazine by free radicals. The DPPH assay measures one electron, such as hydrogen atom donating activity and hence provides a measure of free radical scavenging activity. This assay is suitable for the initial screening of multiple samples, such as plant extracts. Reaction mixtures containing test samples dissolved in DMSO and DPPH in absolute ethanol are incubated at 37°C for 30 min in a 96-well plate and absorbance measured at 515 nm. ... 

Recently, Youssef et al. [24] reported the synthesis of curcumin analogs as potential antioxidant and cancer chemopreventive agents. The general structures of the synthesized analogs are shown in Fig. (8). These compounds were tested for scavenging ability of DPPH free radicals and in an ATP chemiluminescence assay. The SAR conclusions from the results were mainly consistent with the prior conclusions drawn by other researchers. In addition, they found that di-substitution of the central methylene group resulted in decreased antioxidative activity. 

The EO of Ziziphora clinopodioid.es ssp. rigida (blue mint bush) was isolated by hydrodistillation of the dried aerial parts, which was collected during the anthesis. The main compounds are thymol and 1,8-cineole with a content of 8% and 2.7%, respectively. Different extracts were tested by the DPPH assay to determine the antioxidative activity and showed that the free radical scavenging activity of the menthol extract was superior to all other extracts. Polar extracts exhibited stronger antioxidant activity than nonpolar extracts (Salehi et al., 2005). 

Brisdelli et al. (2013) investigated the effects of six lichen metabolites (diffractaic acid, lobaric acid, usnic acid, vicanicin, variolaric acid, protolichesterinic acid) on reactive oxygen species (ROS) level towards three human cancer cell lines, MCF-7 (breast adenocarcinoma), HeLa (cervix adenocarcinoma) and HCT-116 (colon carcinoma). AU tested lichen compounds did not exhibit free radical scavenging activity using the l,l-diphenyl-2-picrylhydrazyl (DPPH) assay. The lichen metabolites did not significantly increase the intracellular ROS level and did not prevent oxidative injury induced by t-butyl hydroperoxide in tested cells. 

Li, Y.-J., J. Chen, Y. Li, and P. Li. 2012. Identification and quantification of free radical scavengers in the flower buds of Lonicera species by online HPLC-DPPH assay coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry. Biomedical Chromatography 26(4) 449-457. 

Sanna, D., G. Delogu, M. Mulas, M. Schirra, and A. Fadda. 2012. Determination of free radical scavenging activity of plant extracts through DPPH assay An EPR and UV-vis study. Food Analytical Methods 5(4) 759-766. 

Alcohol extractives retarded the oxidation of linoleic acid in vitroThe six compounds isolated from Coix hull possessed free radical scavenging activity in the DPPH assay/ The methanolic extract of the seed also inhibited the production of nitric oxide and superoxide ions in activated macrophages in vitro, which supports the anti-inflammatory effect of job s tears/ ... 

The DPPH assay (5) was used to evaluate the free-radical-scavenging capacity of extracts prepared by the methods outlined above, whole berry extract and commercial cranberry juice cocktail (Ocean Spray Inc.). Activity was compared to that of a standard antioxidant (Vitamin E, Aldrich Chemical Co.) measured using the same methods. Varying concentrations of cranberry extracts were mixed with a 60 pM solution of DPPH in methanol. Quenching of the violet DPPH radical was observed as a decrease in absorbance at 515 nm over one hour. EC50 values are measured as the sample concentration required to decrease DPPH absorption by 50%. Results are shown in Table I. The DPPH assay was also used to evaluate the extracts of peel, solids and juice EC50 values are reported in Table V. 

A variety of diarylheptanoids present in Alpinia qfficinarum were determined to display antioxidative activity demonstrated by an anti-lipid peroxidation assay (2). The DPPH assay has been extensively used to test the free radical scavenging ability of various chemicals 8,9) and therefore we used the DPPH method to explore five isolated compounds capacity to act as free radical scavengers. 

The assay of radical scavenging activity was determined using of a stable free radical, DPPH, according to the method of Blois [5]. The decrease in absorbance due to DPPH was measured at 540 nm using a microplate reader. The activity was defined as the ratio of OD540 in the absence of algal extract, to that measured i n the presence of the sample. 

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