This study investigates the effects of seed priming in triticale using extracts from Arthrospira platensis cultivated with copper nanoparticles (CuNP) and copper oxide nanoparticles (CuONP). Results demonstrate significant increases in chlorophyll, carotenoid, and phenolic content, alongside enhanced antioxidant activity in the leaves. Notably, the treatment with nanoparticle-enriched extracts reduced malondialdehyde (MDA) levels, indicating a protective effect against oxidative stress. The findings suggest that spirulina-based extracts, even with the addition of nanoparticles, can enhance crop health, offering a sustainable approach to agriculture.

The article presents the results regarding some peculiarities of the response of microalga Porphyridium cruentum to the action of citrate-stabilized silver and gold nanoparticles with sizes of 10 nm and 20 nm. It has been established that the tested nanoparticles added to the cultivation medium of microalga P. cruentum at the beginning of lag phase did not change significantly its productivity during the cultivation cycle. The effect of this type of nanoparticles on the chlorophyll a and β - carotene synthesis during the cultivation of porphyridium is manifested depending on the size and concentrations applied.

In recent decades, the interest of researchers towards cyanobacteria and algae has increased not only as functional foods or nutraceuticals, but also as sources of natural bioactive components with beneficial health effects, which would serve as an alternative to synthetic drugs, as well as to broaden the spectrum of natural remedies used in the prevention and combating of some diseases. This review presents the results of recent research on the world map regarding the identification of bioactive compounds with antioxidant activity produced by algae and cyanobacteria, analyzed the methods of determining the antioxidant activity of different biochemical compounds classes, as well as the species of cyanobacteria with a rich content of substances with antioxidant effects in order to evaluate the cyanobacterial strains of biotechnological interest and the preparations obtained based on them with high antioxidant activity.

Background: Enhancing Forest seedling resilience and improving soil quality are critical challenges under current climate change conditions. Cyanobacterial exopolysaccharides (EPS) represent a promising biotechnological solution due to their capacity to improve water retention, stabilize soil structure, and modulate rhizosphere interactions, thereby supporting plant adaptation to abiotic stress. Material and Methods: The cyanobacterial strain Nostoc linckia CNMN-CB-03 was cultivated on a range of nutrient media to identify optimal conditions for EPS production. Key physicochemical parameters, including temperature, light intensity, and pH, were systematically optimized. EPS were isolated from the culture medium by ethanol precipitation, then dried to constant weight and formulated into a stable powder via spray drying. The resulting product was applied in a nursery experiment on oak seedlings using localized rhizosphere treatment (0.1 g/L), with untreated plants serving as controls. Results: Comparative evaluation of nutrient media identified MN-1 and BG-11 supplemented with NaHCO₃ as the most efficient systems for EPS biosynthesis, with MN-1 providing consistently higher yields under optimized conditions. Implementation of a stage-specific cultivation regime - 30°C and 60 μmol photons m⁻² s⁻¹ during the initial growth phase, followed by reduced temperature (25°C) and light intensity (35 μmol photons m⁻² s⁻¹), significantly enhanced EPS production, reaching up to 2.68±0.09 g/L after a 16-day cultivation cycle. The developed protocol proved robust and reproducible, integrating biomass cultivation, EPS recovery, and downstream processing into a coherent technological workflow. Spray drying enabled the production of a homogeneous, stable, and easily applicable powder suitable for field use. Nursery trials demonstrated that EPS application did not negatively affect seedling physiological status and contributed to maintaining root system integrity. Moreover, treated seedlings showed indications of improved rhizosphere conditions, likely related to enhanced soil moisture retention and structural stability. These effects are expected to translate into improved establishment rates and root regeneration capacity during the subsequent growing season. Conclusions: Nostoc linckia-derived EPS demonstrate strong potential as a sustainable biostimulant for forestry applications, supporting root protection and improving rhizosphere functionality. The developed technology is experimentally validated, scalable, and relevant for practical implementation in nursery and reforestation systems.

Zinc oxide nanostructures can induce highly variable biological responses depending on their physicochemical properties, concentration, and exposure conditions. This study investigated the effects of multipod ZnO nanostructures (ZnO-MPs) on Limnospira platensis, considering both concentration and application timing. ZnO-MPs (0.01–30 mg/L) were applied at 0, 72, or 120 h after inoculation, and the final biomass and the contents of proteins, carbohydrates, lipids, phycobiliproteins, phycocyanin, chlorophyll, and carotenoids were determined. Final biomass showed relatively limited and non-monotonic variation, whereas biochemical composition was substantially altered. Low concentrations (0.1–1 mg/L), particularly when applied at inoculation, stimulated total phycobiliprotein and phycocyanin accumulation. Higher concentrations strongly reduced protein and phycobiliprotein contents, while promoting carbohydrate and/or lipid accumulation under specific application conditions. Chlorophyll and carotenoids exhibited comparatively moderate and non-monotonic responses. Overall, the results demonstrate that the effects of ZnO-MPs on Limnospira platensis are strongly modulated by concentration and application timing, with biochemical responses being more pronounced than changes in final biomass. These findings emphasize the importance of considering both nanomaterial concentration and application timing when evaluating nanomaterial–cyanobacterium interactions.

Background: Extracts from microalgae and cyanobacteria represent important sources of bioactive compounds with antioxidant potential. Their efficacy depends on their chemical nature and behavior in different environments. For assessing activity in lipid systems, the lowdensity lipoprotein (LDL) oxidation inhibition assay is an appropriate functional model for comparing the capacity to prevent lipid peroxidation. Aim: To comparatively evaluate the inhibitory effect on LDL oxidation of selected bioactive preparations of cyanobacterial and microalgal origin. Materials and methods: Phycobiliproteins from Porphyridium cruentum and Arthrospira platensis (aqueous extracts), as well as astaxanthin from Haematococcus pluvialis (ethanolic extract from aplanospores), were analyzed. The inhibitory effect on LDL oxidation was assessed using a spectrophotometric assay, with results expressed as percentage inhibition at defined concentrations of the tested preparations. Results: All three preparations exhibited inhibitory activity against LDL oxidation, with variations depending on the chemical nature of the bioactive compounds and their concentration. Astaxanthin from Haematococcus pluvialis showed the strongest inhibitory effect, reaching 67.3% at 5 μg/mL, indicating high antioxidant potency at very low concentrations. This effect may be attributed to the specific chemical structure of astaxanthin, which enables activity in lipid systems by localizing within hydrophobic membrane regions and at the lipid-water interface, the primary site of LDL lipid peroxidation initiation. Phycobiliproteins from Arthrospira platensis showed an inhibitory effect of 27.9% at 3.99 μg/mL, suggesting high specific activity at low concentrations. Phycobiliproteins from Porphyridium cruentum induced 43.4% inhibition at 136.6 μg/mL. These differences in potency may be related to the distinct compositions of phycobilin chromophores (phycocyanobilin vs. phycoerythrobilin), which influence radical-scavenging efficiency and electron-transfer processes. Phycocyanin exhibits high activity at low concentrations through chain-breaking antioxidant mechanisms in the early stages of oxidation. In contrast, phycoerythrin may exhibit higher activity at elevated concentrations due to structural differences that affect interactions at the lipid-water interface of LDL. Conclusions: The study demonstrates that algal and cyanobacterial preparations inhibit LDL oxidation to varying degrees, depending on compound type and concentration. Astaxanthin from Haematococcus pluvialis was the most potent inhibitor at μg/mL levels, while phycobiliproteins from Arthrospira platensis and Porphyridium cruentum also exhibited relevant antioxidant activity. The LDL oxidation assay proved to be a suitable model for evaluating antioxidant potential in lipid systems.