The experiment on Zea mays L. cv. Landmark (F1) plants was performed in a greenhouse with UV-B (305–315 nm). The pots with plants were divided into four groups: the first and the second groups were grown, respectively, at low (1.0 kJ m-2 d-1) and high (3.0 kJ m-2 d-1) biological effective dose of UV-B radiation. Half of the pots of each group were sprayed with 0.1% solution of Asahi SL (the third and fourth groups). The intensity of photosynthesis and transpiration, chlorophyll fluorescence, the content of UV-absorbing compounds and radical scavenging activity were measured using DPPH after four and six weeks of UV-B radiation. After six weeks of irradiation with a higher UV-B dose both flavonoid content and antioxidant activity increased by 112% and by 44%, respectively, compared to the plants grown at the lower dose. The plants treated with Asahi SL and exposed to the high dose of UV-B had the content of flavonoids 80% higher than the control ones. Asahi SL decreased scavenging activity in both groups of plants by 17% and 32%, respectively, in comparison with the untreated plants. The intensity of net photosynthesis, the transpiration rate and chlorophyll fluorescence parameters (Fv/Fo, ETR, Rfd) did not differ in most of variants.

Plant secondary metabolites have a variety of functions, including mediating relationships between organisms, responding to environmental challenges, and protecting plants against infections, pests, and herbivores. In a similar way, through controlling plant metabolism, plant microbiomes take part in many of the aforementioned processes indirectly or directly. Researchers have discovered that plants may affect their microbiome by secreting a variety of metabolites, and that the microbiome could likewise affect the metabolome of the host plant. Pesticides are agrochemicals that are employed to safeguard humans and plants from numerous illnesses in urban green zones, public health initiatives, and agricultural fields. The careless use of chemical pesticides is destroying our ecology. As a result, it is necessary to investigate environmentally benign alternatives to pathogen management, such as plant-based metabolites. According to literature, plant metabolites have been shown to have the ability to battle plant pathogens. Phenolics, flavonoids, and alkaloids are a few of the secondary metabolites of plants that have been covered in this study.

The aim of this work was to study the polyphenolic composition of Deschampsia antarctica È. Desv. plants grown at natural conditions on different locations on the Galindez Island, Argentine Islands, the maritime Antarctic. The plants were collected during the summer season of the 26th Ukrainian Antarctic Expedition (2020–2022). The extracts of 21 plants were obtained and the composition of the extracts was analyzed by means of high-performance liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry. The antioxidant properties of the extracts were characterized using the DPPH (2,2-diphenyl-1-picrylhydrazyl) test. The extracts were found to contain large amount of polyphenolic compounds, with flavonoids and phenolic acids, as well as their derivatives, being the most common classes of the phenols. Using the HPLC data the content of various phenols in the plants was systematic studied. It has been found that in all plants the most abundant phenols are flavonoids/flavonoid derivatives (on average about 75% of total mass of phenols). Among the flavonoids, luteolin derivatives predominate (86–94% of the total mass of flavonoids), and, among luteolin derivatives, the main compounds are orientin, orientin 2"- O-β-arabinopyranoside and isoswertiajaponin 2"- O-β-arabinopyranoside (67–83% of the total mass of luteolin derivatives). It has been also found that all the extracts possess the high activity in inhibition of DPPH radicals and that the antioxidant activity of the extracts correlates with total content of phenols in the samples. Thus, Deschampsia antarctica É. Desv. plants are a valuable source of natural phenolic antioxidants, and the most common antioxidants in the extracts are orientin, orientin 2"- O-β-arabinopyranoside and isoswertiajaponin 2"- O-β-arabinopyranoside.

The paper presents data on the total phenolic and flavonoid content in Deschampsia antarctica È. Desv. plants collected from natural habitats, plants cultured in vitro, regenerated plants, and plants cultivated in a growth chamber. It was found that the shoots (aerial parts) had higher phenolic and flavonoid contents compared to the roots. The largest amount of these substances was found in wild plants from Great Yalour Island. The content of phenolics and flavonoids in plants cultured in vitro was generally comparable to that in plants collected from natural habitats except for some clones. HPLC analysis revealed five main metabolites present in similar ratios in the studied samples of wild and in vitro plants. Minor substances varied slightly in different extracts, however their presence did not depend on plant growth conditions. No significant qualitative differences in HPLC profiles were found between the wild and in vitro plants. The studied samples did not contain quercetin, kaempferol and luteolin, whereas orientin was found in all studied samples of D. antarctica.

We determined the level of flavonoids, citric acid and ascorbic acid in hips of rose species from the Caninae section occurring in Poland. We performed phytochemical analyses of 75 samples representing 11 species: Rosaagrestis Savi, R. canina L., R. dumalis Bechst., R. glauca Pourret, R. inodora Fries, R. jundzillii Besser, R. rubiginosa L., R. sherardii Davies, R. tomentosa Sm., R. villosa L. and R. zalana Wiesb. Flavonoid content was determined spectrophotometrically, and organic acid concentrations by HPLC. The content of the studied compounds varied greatly. Interspecific differences in the amount of flavonoids and ascorbic acid were highly significant. The most common species, Rosa canina, showed low average content of vitamin C (0.51 g/100 g of dry matter) and flavonoids (41 mg/100 g DM) and high content of citric acid (3.48 g/100 g DM). Ascorbic acid was highest in R. villosa hips (avg. 2.25 g/100 g DM), flavonoids were highest in R. rubiginosa (72 mg/100 g DM), and citric acid was highest in R. tomentosa (4.34 g/100 g DM). Flavonoid level correlated negatively with the amount of citric acid (r=-0.47, p<0.001). Cluster analysis of rose species based on the content of the investigated compounds confirmed the validity of the division of sect. Caninae into three subsections: Rubiginosae, Vestitae and Rubrifoliae. The phytochemical variation of these roses reflects their probable phylogenetic relationships as determined from morphology.

Hylocereus undatus flower is commonly used as food or for medicinal purposes in south China. To study its antioxidant activity and mechanism we used antioxidant and chemical assays to compare two commercial samples from different locations (Shenjing, Qixing). The difference in antioxidant levels corresponded with differences in chemical content (including total phenolics, total flavonoids, kaempferol and quercetin) between Shenjing and Qixing. The antioxidant ability of H. undatus flower seems attributable to total phenolics (mainly total flavonoids). Kaempferol is one of the main bioactive components. H. undatus flower exerts its antioxidant effects through metal chelation and radical scavenging via hydrogen atom (H•) and electron (e) donation.

Nanotechnology has been widely applied in agriculture, and understanding of the mechanisms of plant interaction with nanoparticles (NPs) as environmental contaminants is important. The aim of this study was to determine the effects of foliar application of cobalt oxide (Co3O4) NPs on some morpho-physiological and biochemical changes of canola (Brassica napus L.) leaves. Seeds were sown in plastic pots and grown under controlled conditions. Fourteen-day-old seedlings were sprayed with different concentrations of Co3O4 NPs (0, 50, 100, 250, 500, 1000, 2000, and 4000 mg L-1) at weekly intervals for 5 weeks. Growth parameters of the shoot (length, fresh and dry weights) were stimulated by low concentrations of Co3O4 NPs (50 and 100 mg L-1) and repressed by higher concentrations. Similar trends were observed in photosynthetic pigment contents. The results indicated that high concentrations of Co3O4 NPs increased lipoxygenase (LOX) activity and the malondialdehyde (MDA), hydrogen peroxide (H2O2), and dehydroascorbate (DHA) contents, but reduced the membrane stability index (MSI), ascorbate (ASC), and glutathione (GSH). Despite the increase of antioxidant capacity (DPPH) and the accumulation of nonenzymatic antioxidants (total flavonoids and flavonols) and osmolytes (proline, glycine betaine (GB) and soluble sugars) at high concentrations of Co3O4 NPs, the growth and photosynthesis were reduced. The defence system activity did not seem to be sufficient to detoxify reactive oxygen species (ROS). Altogether, high concentrations of Co3O4 NPs showed a phytotoxic potential for canola as an oilseed crop.