Antioxidant Activity of Free and Bound Compounds in Quinoa (Chenopodium quinoa Willd.) Seeds in Comparison with Durum Wheat and Emmer
Authors Laus, Gagliardi, Soccio, Flagella, and Pastore are with Dip. di Scienze Agrarie, degli Alimenti e dell'Ambiente, Univ. degli Studi di Foggia, Via Napoli 25-71122 Foggia, Italy. Authors Laus, Soccio, Flagella, and Pastore are with Centro di Ricerca Interdipartimentale BIOAGROMED, Univ. degli Studi di Foggia, Via Napoli 52-71122 Foggia, Italy. Direct inquiries to author Pastore (E-mail: ). Journal of Food Science
(Impact Factor: 1.7).
10/2012; 77(11). DOI: 10.1111/j.1750-3841.2012.02923.x
Antioxidant activity (AA) of quinoa (Chenopodium quinoa Willd.) seeds, as well as of durum wheat (Triticum turgidum L. ssp. durum Desf.) and of emmer (T. turgidum L. ssp. dicoccum Schübler) grains, was evaluated by studying hydrophilic (H), lipophilic (L), free-soluble (FSP) and insoluble-bound (IBP) phenolic extracts using the new lipoxygenase/4-nitroso-N,N-dimethylaniline (LOX/RNO) method, able to simultaneously detect different antioxidant mechanisms, as well as using the Oxygen Radical Absorbance Capacity (ORAC) and the Trolox Equivalent Antioxidant Capacity (TEAC) assays, which measure the scavenging activity against peroxyl and ABTS [2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonate)] radicals, respectively. The species under study were compared with respect to the sum of AA values of H, L and FSP extracts (AAH+L+FSP), containing freely solvent-soluble antioxidants, and AA values of IBP extracts (AAIBP), representing the phenolic fraction ester-linked to insoluble cell wall polymers. The LOX/RNO and ORAC methods measured in quinoa flour a remarkable AAH+L+FSP higher than durum wheat, although lower than emmer; according to the same assays, the IBP component of quinoa resulted less active than the durum wheat and emmer ones. The TEAC protocol also revealed a high AAH+L+FSP for quinoa. Interestingly, the ratio AAH+L+FSP/AAH+L+FSP+IBP, as evaluated by the LOX/RNO and ORAC assays, resulted in quinoa higher than that of both durum wheat and emmer, and much higher than durum wheat, according to the TEAC protocol. This may suggest that antioxidants from quinoa seeds may be more readily accessible with respect to that of both the examined wheat species.
Available from: Julio Sergio Marchini
- "Regarding polyphenols, Alvarez-Jubete et al. (2010) evaluated polyphenol composition and in vitro antioxidant activity of quinoa seeds and found that Favonols quercetin and kaempferol glycosides were the most abundant polyphenols, but also contain protocatechuic acid and a vanillic acid glucoside, and these components are related to the antioxidant activity of quinoa. Laus et al. (2012) compared antioxidant activity of quinoa and durum wheat seed and noticed that the antioxidants of quinoa seeds may be more readily accessible and may represent a better source of natural antioxidant compounds than wheat. It is important to highlight that the effects of polyphenols greatly depend on their transformation by specific components of the gut microbiota via esterase, glucosidase, demethylation, dehydroxylation and decarboxylation activities. "
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ABSTRACT: Abstract A prospective and double-blind study was conducted on 35 women with weight excess who consumed 25 grams of quinoa flakes (QF) or corn flakes (CF) daily during a period of four consecutive weeks. At the beginning (T1) and at the end (T2) of the intervention, total calorie intake was evaluated, anthropometric assessment was performed, blood was collected for the determination of glucose, total cholesterol and fractions, oxidative stress markers, vitamin E and enterolignans. Significant reductions were detected in serum triglyceride (CF group = 133.9 ± 89.4 to 113.7 ± 57 mg/dl and QF group = 112.3 ± 35 to 107.9 ± 33.1 mg/dl), TBARS (CF group = 3.2 ± 0.8 to 2.9 ± 0.5 µmol/l and QF group = 3.06 ± 0.6 to 2.89 ± 0.5 µmol/l) and vitamin E concentrations (CF group = 19.5 ± 5 to 17.9 ± 4 µM and QF group = 17.9 ± 4 to 16.9 ± 3 µM) and an increase in urinary excretion of enterolignans (CF group = 2.05 ± 1.3 to 2.24 ± 1.4 nm/ml and QF group = 2.9 ± 1.6 to 3.2 ± 2.7 nm/l), in both study groups. The reduction of total cholesterol (191 ± 35 to 181 ± 28 mg/dl) and LDL-cholesterol (LDL-c) (129 ± 35 to 121 ± 26 mg/dl), and the increase in GSH (1.78 ± 0.4 to 1.91 ± 0.4 µmol/l) occurred only in the QF group, showing a possible beneficial effect of QF intake.
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ABSTRACT: An improved spectrophotometric assay of phospholipase A2 (PLA2) activity based on the coupled PLA2/lipoxygenase (LOX) reactions using 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PCLIN) as substrate is reported. The PLA2-mediated release of free linoleate is continuously monitored by following the absorbance increase at 234 nm caused by its conversion into the conjugated diene hydroperoxide catalyzed by the coupled soybean LOX-1 reaction. The new protocol includes the use of Tween 20 (3 μL/μmol phospholipid) as surfactant and of ethanol (15 μL/mL reaction mixture), that ensure clearness of reaction mixture and linear increase of absorbance in the course of reaction. This method was tested on a purified secretory PLA2 from honey bee venom (HBV-PLA2). The enzyme did not discriminate among PCLIN, phosphatidylcholine, and phosphatidylethanolamine, but showed the highest rate using 1,2-dilinoleoyl-sn-glycero-3-phosphatidylcholine (PCDILIN). Nevertheless, the use of PCDILIN is not recommended, as it may induce an overestimation of enzyme activity, because not only the free linoleate, but also the reaction product 1-linoleoyl-lysophosphatidylcholine, are known to be oxidized by LOX. HBV-PLA2 showed maximal activity at pH 9.0, hyperbolic kinetics (Km, 74.2±2.9 μM; Vmax, 827±7 μmol/min/mg protein) and competitive inhibition (Ki about 5 μM) by palmityl trifluoromethyl ketone, a classical PLA2 inhibitor. Interestingly, the HBV-PLA2/soybean LOX-1 coupled reactions also allow an accurate assay of PCLIN concentration. In the whole, these results demonstrate that this improved PLA2/LOX assay allows a very accurate, simple, and rapid measurement of enzyme activity and substrate concentration.
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ABSTRACT: Epidemiological studies associated consumption of whole-durum wheat products with reduced incidence of chronic diseases, diabetes and cancer. These health benefits have been mainly attributed to antioxidant activity (AA) due to the unique phytochemical content of wheat. Milling, extrusion and drying process can influence the activity of these beneficial compounds. In order to have a deep insight into the changes of nutritional value from raw material to pasta, the aim of this study was: i) to compare the AA of hydrophilic and lipophilic extracts of five durum wheat genotypes along the pasta chain; ii) to evaluate the changes in antioxidant properties of whole meal after processing in semolina and pasta. To this aim TEAC (Trolox Equivalent Antioxidant Capacity) assay based on ABTS(center dot+)[2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging activity was used due to its high reproducibility and simplicity. Low genotype variability was observed for both hydrophilic and lipophilic extracts. Milling process caused a significant decrease in AA due to the removal of the outside layers of the kernel. This decrease was more marked for lipophilic extracts due to the different distribution of hydrophilic and lipophilic antioxidants along the kernel. Pasta making process while determining a further decrease in AA of lipophilic extracts caused a slight increase in AA of hydrophilic extracts compared to semolina. This might be due to melanoidins formed during Maillard reaction. Only for lipophilic extracts a predictive evaluation of semolina and pasta ABTS(center dot+) scavenging activity was possible by testing raw material.
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