Antioxidant Activity of Free and Bound Compounds in Quinoa (Chenopodium quinoa Willd.) Seeds in Comparison with Durum Wheat and Emmer
ABSTRACT 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 Schubler) 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 (AA(H+L+FSP)), containing freely solvent-soluble antioxidants, and AA values of IBP extracts (AA(IBP)), representing the phenolic fraction ester-linked to insoluble cell wall polymers. The LOX/RNO and ORAC methods measured in quinoa flour a remarkable AA(H+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 AA(H+L+FSP) for quinoa. Interestingly, the ratio AA(H+L+FSP)/AA(H+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.
- SourceAvailable from: Julio Sergio Marchini
[Show abstract] [Hide abstract]
- "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. "
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.International Journal of Food Sciences and Nutrition 12/2013; 65. DOI:10.3109/09637486.2013.866637 · 1.20 Impact Factor
- [Show abstract] [Hide abstract]
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.Journal of the Korean Society for Applied Biological Chemistry 08/2013; 56(4):369-376. DOI:10.1007/s13765-013-3018-8 · 0.54 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: A common protocol for the extraction of phenolic aglycones or bound phenolics in plants generally involves hydrothermal hydrolysis in an aqueous methanol or ethanol solution containing 2-4 N HCl. However, as shown in the present study, this process also forms 5-(hydroxymethyl)furan-2-carbaldehyde (HMF) and its derivative products 5-(methoxymethyl)furan-2-carbaldehyde (MMF) and 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), as identified by HPLC-DAD-ESI-MS/MS, and NMR. These compounds are commonly misidentified as phenolics due to similar UV absorption at 280 nm. In this study, production of HMF, MMF and EMF was shown to be dependent on the solvent condition, duration and temperature of hydrolysis. Fruits and vegetables produced HMF more readily than grains. HMF and its derivatives were subjected to various spectrophotometric antioxidant assays (DPPH, FRAP and ORAC) and displayed antioxidant activity only in the ORAC assay. Results of this study help avoid overestimation of the phenolic contents and antioxidant activity of plant foods.Journal of Agricultural and Food Chemistry 05/2014; 62(20). DOI:10.1021/jf500518r · 3.11 Impact Factor