Aging is accompanied by gradual accumulation of molecular damage within cells in response to oxidative stress resulting from adverse environmental factors, inappropriate lifestyle, and numerous diseases. Adequate antioxidant intake is a key factor of proper diet. The study aimed to assess the antioxidant/antiradical capacities of Cucurbita fruits (18 cultivars of the species: C. maxima Duch., C. moschata Duch., C. pepo L., and C. ficifolia Bouché) grown in central Europe. The analyses were based on the FRAP (ferric reducing antioxidant power), CUPRAC (cupric ion reducing antioxidant capacity), and DPPH (2,2-diphenyl-1-picrylhydrazyl radical) assays. The content of phenolic compounds and β-carotene was evaluated with HPLC (high performance liquid chromatography), while the main macro- and micronutrients by ICP-OES (inductively coupled plasma mass spectrometry). The results revealed high intraspecies variability within the Cucurbita genus. The Japanese ‘Kogigu’ fruits were distinguished as extraordinary sources of phenolic compounds, including syringic and protocatechuic acids, catechin, and kaempferol. Another popular cultivar ‘Hokkaido’ exhibited the highest antioxidant and antiradical capacities. Most of the fruits proved to be rich sources of zinc and copper. The obtained data are discussed in the context of optimized nutrition of the elderly and suggest that Cucurbita fruits should become daily components of their diet.

In marine algae, vanadium (V) regulates the cellular uptake of iodine (I) and its volatilization as I₂, the processes catalyzed by vanadium-dependent haloperoxidases (vHPO). Relationships between I and vanadium V in higher plants, including crop plants, have not yet been described. Little is known about the possibility of the synthesis of plant-derived thyroid hormone analogs (PDTHA) in crop plants. The activity of vHPO in crop plants as well as the uptake and metabolism of iodosalicylates in lettuce have not yet been studied. This studyaimed to determine the effect of V on the uptake and accumulation of various forms of I, the metabolism of iodosalicylates and iodobenzoates and, finally, on the accumulation of T3 (triiodothyronine—as example of PDTHA) in plants. Lettuce (Lactuca sativa L. var. capitata ‘Melodion’ cv.) cultivation in a hydroponic NutrientFilm Technique (NFT) system was conducted with the introduction of 0 (control), 0.05, 0.1, 0.2, and 0.4 µM V doses of ammonium metavanadate (NH₄VO₃) in four independent experiments. No iodine treatment was applied in Experiment No. 1, while iodine compounds were applied at a dose of 10 µM (based on our own previous research) as KIO₃, 5-iodosalicylic acid (5-ISA) and 3,5-diiodosalicylic acid (3,5-diISA) in Experiment Nos. 2, 3 and 4, respectively. When lettuce was grown at trace amount of I in the nutrient solution, increasing doses of V contributed to the increase of (a) I content in roots, (b) I uptake by whole lettuce plants (leaves + roots), and (c) vHPO activity in leaves (for doses 0.05–0.20 µM V). Vanadium was mainly found in roots where the content of this element increased proportionally to its dose. The content of V in leaves was not modified by V introduced into the nutrient solution. We found that5-ISA, 3,5-diISA and T3 were naturally synthesized in lettuce and its content increased when 5-ISA, 3,5-diISA were applied. Quantitative changes in the accumulation of organic metabolites (iodosalicylates and iodobenzoates) accumulation were observed, along with increased T3 synthesis, with its content in leaves exceeding the level of individual iodosalicylates and iodobenzoates. The content of T3 was not affected by V fertilization. It was concluded that iodosalicylates may participate in the biosynthesis pathway of T3—and probably of other PDTHA compounds.

Background and aims The strong sorption of iodine in soils is a major factor that limits its uptake by plants. The aim of this study was to evaluate the influence of Humistar (a concentrate of exogenous humic acids 12 % w/w and fulvic acids 3 % w/w; abbreviated: HU) applied with KI or KIO₃ on the efficiency of iodine biofortification, yield and the accumulation of undesirable compounds in spinach. Methods Methods of iodine application with or without HU were tested in two pot experiments and a hydroponic study with spinach cultivation. The spinach biomass and the content of iodine, soluble oxalates, Cd and Pb in leaves were determined. The physicochemical properties and chemical composition of the soil and media were analysed. Results No negative influence of iodine and HU on spinach yield was observed. Fertigation with iodine resulted in a higher efficiency of iodine biofortification than its application pre-sowing (particularly for KIO₃), with no increase in the Cd and Pb content in spinach plants compared to the control. Conclusion The improvement of iodine uptake and root-to-leaf transfer (represented by higher transfer factor values) in spinach can be obtained by the application of HU via plant fertigation with IO₃ ⁻. The level of soluble oxalates in spinach grown in the pot experiments was not affected.

Fruits of several, mainly Polish cultivars of floricane- and primocane-fruiting red raspberry (Rubus idaeus), black raspberry (Rubus occidentalis) and blackberry (Rubus fruticosus), grown in central Europe during two successive vegetation periods, were investigated. The content of phenolic compounds, including anthocyanins, as well as antioxidant properties of fruit extracts were analysed. A number of methods were employed: ferric ion reducing antioxidant power (FRAP), cupric ion reducing antioxidant capacity (CUPRAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity involving both colorimetric and EPR spectrometric measurements. From among all the tested fruits black raspberries had the largest antioxidant capacity as verified by all methods used in this study. These berries were also the most abundant in phenolic and anthocyanin compounds. Blackberries were characterised by larger antioxidant capacity than red raspberry fruits which were accompanied by higher content of total phenolics and anthocyanins. Berries of primocane-fruiting cultivars, often used for intensive agricultural production, generally did not differ in the total phenolic and anthocyanin content as well as in the antioxidant capacity as compared to the traditional, floricane-fruiting ones. The research contributes to deep characterisation of central European berry fruits which due to their high content and large diversity of health-beneficial compounds are classified as natural functional food.