Evaluation of antioxidant activity of leafy vegetables and beans with myoglobin method

Health-Promoting Nutrients and Potential Bioaccessibility of Breads Enriched with Fresh Kale and Spinach

Bread is a staple food and can be a potential product to be enriched with various deficient nutrients. The objective of the study was to characterize the nutritional properties of toasted bread enriched with 10% and 20% of kale and wholemeal bread with 20% and 40% of spinach. The supplementation increased the phenolic content up to 2−3 times in the bread with the addition of 20% spinach and 40% kale. The highest antioxidant properties were noticed in extracts of bread with 20% kale. The in vitro digestion released the hydrophilic and lipophilic antioxidative compounds, leading to higher bioaccessibility of the breads enriched with these selected green vegetables. Even more than a 2-fold increase in folate content was observed in breads with the greatest addition of kale (20%) and spinach (40%), from 18.1 to 45.3 µg/100 g and from 37.2 to 83.2 µg/100 g, respectively, compared to the non-enriched breads. Breads with spinach showed significantly (P < 0.05) higher contents of all of the tested minerals, Cu, Mn, Fe, Zn, Mg, Ca, Na, K, and P, whereas kale enriched breads showed most of them. The results suggest that the addition of fresh green vegetables can enhance the daily supply of micronutrients and significantly increase the bioavailability of bioactive compounds with high antioxidant status.

Antioxidant and anti-proliferative activity of free, conjugates and bound phenolic compounds from tomato and industrial tomato by-product

The aim of this study was to evaluate the antioxidant and anti-proliferative activity of different fractions of phenolic compounds from tomato and tomato by-product. Soluble free phenolics and bound phenolics (BP) fractions from saladette tomato and industrial tomato by-product as well as, conjugated acid-hydrolysable phenolics (AHP) and alkaline-hydrolysable phenolics (AKHP) from saladette tomato, grape tomato and industrial tomato by-product, were tested. The scavenging effects of phenolic fractions on superoxide anion were determined using the PMS-NADH-NBT system. The myoglobin protection ratios of samples against hydroxyl radical were evaluated and the anti-proliferative effects in the MCF-7 breast cancer cell line were determined. AHP fraction from tomato by-product and AKHP fraction from grape and saladette tomato showed the highest inhibitory capacity of the superoxide anion (p ≤ 0.05). All samples had a myoglobin protection ratio from 30 to 50%. Regarding to cytotoxicity assays, all phenolic fractions from tomato by-product, as well as, BP, AHP, AKHP from saladette tomato and AHP from grape tomato showed important anti-proliferative activity against MCF-7 breast cancer cell line (IC₅₀ < 20 μg/mL). From the results, we can conclude that tomato and tomato by-product are a good source of natural compound with important antioxidant and anti-proliferative activity.

Antioxidant activities of a peptide derived from chicken dark meat

Antioxidant activities against hypochlorite ions and peroxyl radicals of a chicken dark meat hydrolysate digested with pepsin were examined with the myoglobin method based on the structure change of myoglobin due to redox reaction with reactive oxygen species (ROS). A peptide that showed strong antioxidant activity against the peroxyl radical was isolated from the hydrolysate using HPLC equipped with a hydrophobic-interacting column. The sequence of the first five amino acid residues of the peptide was determined as YASGR (Tyr-Ala-Ser-Gly-Arg), and this sequence matched with the amino acid residues 143-147 of chicken β-actin (GenBank: CAA25004.1). The synthetic peptide YASGR showed very high antioxidant activity against the peroxyl radical. Antioxidant activities of the free amino acids, confirmed that the tyrosine residue of this peptide was possibly responsible for antioxidant activity.