Free radical scavenging DPPH radicals

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. 

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. 

Xanthosoma violaceum, Araceae, widely distributed in Dominican Republic, Puerto Rico, Guatemala, and Equator, was investigated for in vitro antioxidant and free-radical scavenger activities. The fraction rich in C-glycosylflavones showed with l,l-diphenyl-2-picryl-hydrazyl radical (DPPH) test an EC50 of 11.6 pg/ml, compared with quercetin (2.3 pg/ml) and a-tocopherol (10.1 pg/ml). 

Jothy ST, Zuraini Z, Sasidharan S. Phytochemicals screening, DPPH free radical scavenging and xanthine oxidase inhibihory activihes of Cassia fistula seeds extract. Journal of Medicinal Plants Research. 2011 5(10) 1941-1947. 

Ciesla t, Kryszen J, Stochmal A, Oleszek W, Waksmundzka-Hajnos M. Approach to develop a standardized TLC-DPPH test for assessing free radical scavenging prop-erhes of selected phenolic compounds. Journal of Pharmaceuhcal and Biomedical Analysis. 2012 70 126-135. 

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). 

The free radical scavenging effects of compounds 57 derived from dihydro-pyrimidines 56 (Scheme 12) was also examined by the DPPH method and by measuring hydroxyl radical scavenging activity (RSA) [33]. It was found that compounds derived from the thioureas had the best antioxidant activities. Compounds 58 and 59 were the most potent and had comparable activity to quercetol (Table 4). 

Famesylhydroquinone 330 was isolated from the mycelium of a marine-derived fungus of the genus Penicillium. This compound exhibited potent free radical scavenging activity (IC50, 12.5 pM) against the DPPH. 

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. 

The development of free radical scavenging capacity as determined by the DPPH method was studied during aging of selected red Spanish wines (Larrauri et al.,... 

Several free radical scavenging activity tests (hydrogen peroxide, superoxide, and DPPH) have been employed to evaluate the extracts of hazelnut kernel and hazelnut by-products. This information... 

Plant foods contain a number of bioactive substances, including phenoUcs. Phenolics such as flavonoids, phenolic acids, lignans and tannins have antioxidant properties, whilst the fermentation process has been d onstrated to modify the amount of these contents. l,l-Diphenyl-2-picryldrazyl (DPPH) and 2,2 -azinobis-(3-ethylbenzothi-azoline-6-sutfonic acid) (ABTS) are tests commonly used to detennine the free radical-scavenging effectiveness of componnds in evaluating the antioxidant activity of food systems. 

Experiments of disappearance of DPPH (2,2 diphenyl-l-picrylhydrazyl radical), which is widely used to test the ability of compounds to act as free radical scavengers or as hydrogen donors at different temperatures, are shown in Figure 1. Fresh distilled styrene or styrene and recently sublimated MA and a solution 10 M of DPPH were put in a vial in the presence OH-TEMPO or without it, and heated at 80°, 100° or 120 °C after oxygen had been... 

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). 

This method, described by T. Sarraf, involves a free radical scavenger diphenyl picryl hydrazil, DPPH. DPPH, stable at room temperature, is added in excess to the ozonized sample and reacted at 110°C. The cleavage of peroxides and hydroperoxides to RO and HO generates free radicals which are captured by DPPH. After precipitation of polyethylene, the excess of DPPH in the filtrate is back-titrated by colorimetry at 520 nm, and the amount of initial peroxides and hydroperoxides can be obtained from the result. 

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