Total Antioxidant Capacity of Plants

Anthocyanins (delphinidin 3-sambubioside and cyaniding 3-sambubioside) are the main contributors to TAC of petal extracts of roselle (Hibiscus sabdariffa L.), accounting for 51 % of TAC of the extracts. About 24% of TAC was due to phenolic 

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Pellegrini, N. et al.. Total antioxidant capacity of plant foods, beverages and oils consumed in Italy assessed by three different in vitro assays, J. Nutr. 133, 2812, 2003. 

ABTS radical anions were used according to the method of (Kim et al., 2003). In brief, 1.0 mM of 2, 2 -azobis (2-amidino-propane) dihydrochloride (AAPH), a radical initiator, was mixed with 2.5 mM ABTS in phosphate-buffered saline (pH 7.4) and the mixed solution was heated in a water bath at 68 °C for 13 min. The resulting blue-green ABTS solution was adjusted to the absorbance of 0.650 + 0.020 at 734 nm with additional phosphate-buffered saline. 20 il of sample were added to 980 (iL of the ABTS radical solution. The mixture incubated in a 37°C water bath under restricted light for 10 min. A control (20 iL 50% methanol and 980 mL of ABTS radical solution) was run with each series of samples. The decrease of the absorbance at 734 nm was measured (Cary 50 Scan UV-Visible apparatus) at an endpoint after 10 min. Total antioxidant capacity of plant parts is expressed as mg / g of dry weight of vitamin C equivalents (VCEAC). The radical stock solution had to be freshly prepared and all measurements of the tested samples were repeated at least three times. 

Prieto et al. (1999) reported another spectrophotometric method for the quantitative determination of antioxidant capacity based on the reduction of Mo(VI) to Mo(V) by vitamin E in acidic conditions with incubation at 95°C for 90 min. The subsequent green phosphate/Mo(V) complex, after cooling at room temperature was monitored at 695 nm with a calibration range of 0.2-2 x 10 M (r = 0.997) and a detection limit of 0.135 pmol vitamin E. The method was applied for measurement of total antioxidant capacity of plant extracts and to determine vitamin E in a variety of grains and seeds, including corn and soybean. The recovery of vitamin E from seeds was determined by supplementing the samples with the different vitamin E isomers or a-tocopherol acetate as internal standard and applying both the proposed method and a standard HPEC assay (Huo et al., 1996) and yielded a recovery of 93%-97% tocopherols. 

Miller and Rice-Evans have recently developed a method to measure the total antioxidant capacity of solutions of pure compounds, as well as plasma, serum and other body fluids, plant extracts, beverages, etc. [125-126]. This method is based on the inhibition of the absorbance of the 2,2 -azinobis(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS) radical cation (ABTS,+) by antioxidants. Although the chromophore ABTS + has... 

Regarding antioxidants, the parameter total dietary antioxidant capacity (TDAC) can be taken to reflect antioxidant intake it is defined as the antioxidant capacity of all plant foods and beverages (alcoholic and nonalcoholic) consumed daily in a diet and may represent the amount of antioxidant units (Trolox equivalents) present daily in the human gut (Saura-Calixto and Goni 2006). 

In recent decades, the extracts of leaves, seeds and roots of M. oleifera have been extensively studied for many potential uses including wound healing (31, 139, 140). The uses of the plants in wound healing are rationalised on the basis of their antioxidant capacity (52). M. peregrina has been shown to inhibit the DPPH radical at 89-93%, after 15 min of incubation at a test concentration of 50 pg/mL. M. peregrina has been shown to have total antioxidant capacity as gallic acid equivalent of 814 mg/g of ethanol extracts in the phosphomolybdenum assay. 

Due to the chemieal diversity of antioxidant compounds present in natural samples, it is unrealistie to separate eaeh antioxidant component and study it individually. In addition, levels of single antioxidants do not neeessarily reflect their total antioxidant capacity because of the possible synergistie interactions among the antioxidant eompounds in a food mixture, for that Banos et al., 2011, recommend to evaluated the antioxidant properties of the entire extraets obtained from the plant [36],... 

Katalinic V, Milos M, Kulisic T, Juldc M (2006) Scretming of 70 medicinal plant extracts for antioxidant capacity and total phenols. Food Chtan 94 550... 

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