Phenolic Contents and Free Radical Scavenging Activity in Some Leafy Vegetables

New Mutant Amaranth Varieties as a Potential Source of Biologically Active Substances

Amaranth species represent a diverse group of plants. Many of them are a rich source of secondary metabolites with many positive biological effects. Total phenolic, total flavonoid and rutin content, antioxidant activity against superoxide and hydroxyl radicals, FRAP (Ferric-reducing ability of plasma) assay and DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging assay were determined in ethanol extracts of dried leaves of the new Slovak amaranth varieties ‘Pribina’ and ‘Zobor’. The amount of total phenolic substances (‘Pribina’ GAE 38.3 mg.g⁻¹ DM and ‘Zobor’ GAE 26.1 mg.g⁻¹ DM), content of total flavonoids (‘Pribina’ QE 26.5 mg.g⁻¹ DM and ‘Zobor’ QE 20.3 mg.g⁻¹ DM) and rutin (‘Pribina’ 50.8 mg.g⁻¹ DM and ‘Zobor’ 15.2 mg.g⁻¹ DM) were higher in the variety ‘Pribina’, compared to the variety ‘Zobor’. A statistically higher antioxidant activity against superoxide radical (1.63%·mg⁻¹g⁻¹ DM), hydroxyl radical (3.20%.mg⁻¹g⁻¹ DM), FRAP assay (292.80 µmol.L⁻¹·mg⁻¹.g⁻¹ DM) and DPPH (54.2 ± 1.78 µg.mL⁻¹ DM) were detected in the ‘Pribina’ variety. Antiradical and antioxidant activities of both extracts showed high positive correlations in relation to the content of total phenolic substances, total flavonoids and rutin. Amaranth is an undemanding crop on specific environmental conditions and is resistant to abiotic and biotic stress.

Proximate Composition, Minerals and Antioxidant Activity of Artichoke Leaf Extracts

In this study, leaf extracts from the Green Globe cultivar of artichoke (Cynara scolymus L.), a herbaceous plant of the Asteraceae family, were analyzed to determine the levels of basic nutrients, selected macroelements (K, P, Ca, Mg, and Na) and microelements (Zn, Fe, Mn, Cr, Pb, Cd, and Ni), and their ratios. The antioxidant activity (aa) of the extract was evaluated using ABTS˙⁺ and DPPH˙⁺ radicals and the ferric reducing antioxidant power assay (III) (FRAP). Total polyphenolic content was also determined. Macroelement concentrations in the artichoke leaf extract can be presented in descending order as follows: K > P > Ca > Mg > Na. Microelement content in the extract was as follows: Zn > Fe > Cr > Mn. We determined the ratios of elements in artichoke leaf extracts and compared them against the recommended dietary allowance, adequate intake, or tolerable upper intake level. Mean total phenolic content in artichoke leaf extracts was high - 2795 mg CAE/100 g dry matter (DM). The ABTS˙⁺ assay showed a very high ability of artichoke extract to scavenge free radicals (79.74%), and the antioxidant capacity measured at 1060.8 Trolox/1 g DM. The results show that artichoke extract is a valuable source of minerals and antioxidants that could have applications in the prevention of chronic non-communicable diseases caused by oxidative damage.