Heavy metal stress can lead to many adverse effects that inhibit cellular processes at various levels of metabolism, causing a decrease in plant productivity. In response to environmental stressors, phenolic compounds fulfill significant molecular and biochemical functions in plants. Increasing the biosynthesis of phenolic compounds in plants subjected to heavy metal stress helps protect plants from oxidative stress. A pot experiment was carried out to determine the effect of the accumulation of copper (Cu) and lead (Pb) salts at concentrations of 200, 500, and 1000 ppm on seed germination, the activity of enzymes in the phenylalanine ammonia-lyase pathway (PAL) and tyrosine ammonia-lyase (TAL), along with the total phenol and flavonoid contents in seedlings of hybrid Triticum aestivum L. (winter wheat) cultivars. The accumulation of heavy metals, especially Cu, had a negative impact on the seed germination process. The cultivar “Hyacinth” reacted most strongly to heavy metal stress, which was confirmed by obtaining the lowest values of the germination parameters. Heavy metal stress caused an increase in the activity of PAL and TAL enzymes and an increase in the accumulation of phenolic compounds. Under the influence of Cu, the highest activity was shown in cv. “Hyvento” (especially at 200 ppm) and, due to the accumulation of Pb, in cv. “Hyacinth” (1000 ppm) and cv. “Hyking” (200 ppm). The cultivar “Hyking” had the highest content of phenolic compounds, which did not increase with the application of higher concentrations of metals. In other cultivars, the highest content of total phenols and flavonoids was usually observed at the lowest concentration (200 ppm) of the tested heavy metals, Cu and Pb.

Microalgae are photosynthetic, eukaryotic organisms that are widely used in the industry as cell factories to produce valuable substances, such as fatty acids (polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), sterols (sitosterol), recombinant therapeutic proteins, carbohydrates, vitamins, phenolic compounds (gallic acid, quercetin), and pigments (β-carotene, astaxanthin, lutein). Phenolic compounds and carotenoids, including those extracted from microalgae, possess beneficial bioactivities such as antioxidant capacity, antimicrobial and immunomodulatory activities, and direct health-promoting effects, which may alleviate oxidative stress and age-related diseases, including cardiovascular diseases or diabetes. The production of valuable microalgal metabolites can be modified by using abiotic stressors, such as light, salinity, nutrient availability, and xenobiotics (for instance, phytohormones).

The study objective was a comparative analysis of rapeseed and multifloral honey enriched by flowers of six plant species: lungwort (Pulmonaria officinalis L.), high mallow (Malva sylvestris L.), cowslip primrose (Primula veris L.), coltsfoot (Tussilago farfara L.), lawn daisy (Bellis perennis L.), and black elderberry (Sambucus nigra L.). The honey was enriched with dry flowers and plant extracts at a level of 1%, 2%, and 4% (w/w). Antioxidant capacity was measured via two different methods: DPPH and ABTS assay. Total phenolic content and total flavonoid content were determined using colorimetric methods. The highest radical scavenging capacity determined by the DPPH assay was observed in rapeseed honey with a 4% dried cowslip primrose (Primula veris L.) flower addition, which was more than 50 times higher than the activity for pure rapeseed honey. Almost 100% of the radical scavenging capacity was found for rapeseed and multifloral honeys with cowslip primrose (Primula veris L.), especially for the 4% dried flower addition, more than six times that of the control samples measured using the ABTS test. Multifloral honeys enriched with black elderberry (Sambucus nigra L.) and cowslip primrose (Primula veris L.), with a 2% and 4% plant material addition, both as an extract and as dried flowers, were characterised by the highest total phenolic content. The highest enrichment effectiveness was observed for dried flowers of lungwort (Pulmonaria officinalis L.), black elderberry (Sambucus nigra L.), and high mallow (Malva sylvestris L.), where the flavonoid content increased more than nine times compared to the honey samples without additions. The content of biologically active substances in honey enriched with flowers gives hope for new applications of the health-promoting substances contained in wild plants.

Grape pomace, a polyphenol-rich byproduct of wine production, represents a promising source of bioactive compounds for managing diabetes and its complications. This study evaluates the effect of a novel grape pomace extract on carbohydrate and lipid metabolism, and oxidative stress in type 1 diabetes mellitus. Diabetes was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin. Starting on day 14 post-induction, rats received oral grape pomace extract at a dose of 45 mg of polyphenols/kg body weight daily for 14 days. On day 28 of the experiment, blood plasma was collected. One-way ANOVA with post hoc testing revealed a hypoglycemic effect of grape pomace extract, as evidenced by reduced fasting blood glucose and improved postprandial glycemic responses. The extract also ameliorated dyslipidemia, lowering total cholesterol and triglycerides while increasing high-density lipoprotein levels and paraoxonase activity in plasma of diabetic rats. Antioxidant defenses were enhanced, as indicated by elevated superoxide dismutase, catalase, and glutathione peroxidase activities, along with reduced protein carbonyls, TBA-reactive products, and lipofuscin in blood plasma following extract administration. These findings demonstrate the metabolic and antioxidant potential of grape pomace polyphenols, although further investigations are needed to elucidate the underlying molecular mechanisms.

Microalgae are a rich source of bioactive metabolites, including unsaturated fatty acids, chlorophylls, carotenoids, and phenolic compounds with antioxidant and nutraceutical potential. Salicylic acid (SA) and its volatile ester, methyl salicylate (MS), are well-known elicitors of secondary metabolism in higher plants, yet their mechanisms of action in green microalgae, particularly the effects of MS, remain poorly understood. Therefore, we evaluated how salicylates applied at concentrations of 0.1, 1, and 10 µM affect the growth and accumulation of bioactive compounds in a high-productivity clone of Planktochlorella nurekis, combining gas chromatography coupled mass spectrometry (GC-MS) fatty acid profiling with spectrophotometric determination of pigment levels, total phenols, and L-phenylalanine ammonia-lyase (PAL) activity. SA increased cell number and size, whereas 0.1 µM MS resulted in a six-fold gain in cell number. Accordingly, 10 µM MS raised chlorophyll b levels—nearly three-fold (from 76 to 211 µg per g D.W.)—and total carotenoids—roughly four-fold (129 to 520 µg per g D.W.)—while both elicitors significantly increased the monounsaturated fatty acid fraction (from 29% to about 40%). Notably, 10 µM SA lowered the levels of saturated fatty acids. Moreover, 10 µM MS doubled the PAL activity and increased the total phenols by 17% compared to the control. Thus, SA and MS act as effective elicitors of high-value metabolites in P. nurekis.

Is it possible that the addition of wild-growing flowers with anti-inflammatory applications can improve the antioxidant properties of rapeseed and multifloral honey? The study objective was a comparative analysis of two honey varieties enriched by flowers of six plant species, based on the content of the antioxidant capacity as well as total flavonoids and phenolic content. Experiments demonstrated that at each level of enrichment there was an improvement in antioxidant properties compared to honey of both varieties without additives, especially in the case of dried flowers. Primula veris L. and Pulmonaria officinalis L. improved the antioxidant properties and phenolic content most effectively in honey at all levels of enrichment. Rapeseed-type honey produces a better matrix for the incorporation of natural plant metabolites into honey. The content of biologically active substances in honey enriched with flowers gives hope for new applications of health-promoting substances contained in wild plants.