Ivana Šola

The Mediterranean region is a hotspot for many plants rich in bioactive compounds due to its climate and geological regime. Aerial parts of native perennials Satureja montana and Teucrium montanum (Lamiaceae) were spectrophotometrically compared on the levels of antioxidant potential, phenolics, soluble sugars and proteins. S. montana had a notably higher antioxidant potential than T. montanum across all three assays applied, ABTS, DPPH and FRAP. This was accompanied by a significantly higher amount of most analyzed groups of phenolic compounds. Compared with T. montanum, S. montana had more total phenols (45.09 mg galic acid equivalents (GAE)/g dw; 1.54-fold higher), flavonoids (137.17 mg quercetin equivalents (QE)/g dw; 1.42-fold higher), flavonols (2.24 mg QE/g dw; 1.58-fold higher), phenolic (39.52 mg caffeic acid equivalents/g dw; 1.45-fold higher) and hydroxycinnamic acids (180.84 mg cinnamic acid equivalents /g dw; 1.57-fold higher), as well as tannins (23.95 mg GAE/g dw; 2.17-fold higher). Total proteins were also higher in S. montana (96.12 mg bovine serum albumin equivalents/g dw; 6.50-fold higher). On the contrary, total proanthocyanidins were significantly higher in T. montanum (1.46 mg catechin equivalents/g dw; 1.55-fold higher), as well as soluble sugars (49.86 mg sucrose equivalents/g dw; 1.42-fold higher). Finally, S. montana exhibited a 1.5-fold higher phenolic index than T. montanum, whereas T. montanum showed a 1.3-fold higher metabolic index than S. montana. Therefore, S. montana prioritizes synthesis of defense-related compounds, while T. montanum invests more energy into growth-related metabolism. Based on the results, S. montana had higher phenolic content, suggesting a greater potential for phenolic-associated bioactivity. However, further analyses regarding bioavailability, toxicity and nutritional composition are required for assessment of its nutritional quality.

Modern lifestyle and diet, characterized by low fruit and vegetable intake, contribute to the rising prevalence of diet‐related disorders, particularly cardiovascular diseases. This highlights the importance of nutrition‐based strategies for maintaining human health. Broccoli microgreens, due to their short growth cycle and high content of bioactive compounds, such as polyphenols and glucosinolates, represent a promising functional food. Although in vivo and in vitro studies have demonstrated beneficial physiological effects of Brassica‐derived compounds, excessive intake may also produce adverse, anti‐nutritional effects. Given that broccoli extracts are frequently consumed in the form of various dietary supplements and commercially available cruciferous vegetables, we investigated the in vivo effects of water extracts from broccoli sprouts (BWE) grown at 23°C and 38°C on hematological parameters and myocardial tissue in healthy Swiss mice. Metabolic, structural, inflammatory, and redox changes were evaluated to determine whether growth temperature alters phytochemical composition and consequently affects blood and myocardial physiology. Administration of BWE at a dose of 300 mg/kg body weight significantly reduced mean platelet volume ( p ≤ 0.05) and enhanced myocardial antioxidant capacity ( p ≤ 0.05; p ≤ 0.0001). Differences in glucosinolate and polyphenol profiles between treatments were associated with increased nitric oxide (NO) production in mice receiving BWE from sprouts grown at 23°C and elevated total glutathione (tGSH) levels in those treated with BWE from sprouts grown at 38°C ( p ≤ 0.05). These findings suggest that BWE may exert antiplatelet effects and improve myocardial antioxidant status, indicating its potential role in reducing cardiovascular risk.

Research background. The outer scales of common onion (Allium cepa L.) are often discarded as biological waste but they can be an interesting source of polyphenols with antioxidant and antidiabetic properties that can be used in the food and pharmaceutical industries. Experimental approach. The aim of this study is to use dried chamomile (Matricaria chamomilla L.) flowers containing 6 % flavonoid apigenin in the form of a water extract to improve the polyphenol profile, and the antioxidant and antiglycation activity of onion outer scales. “Red Carmen” onion bulbs with roots were exposed to deionized water (control) and chamomile water extract (test treatment) in a phytotron (23 °C/16 h day/8 h dark). Fourier transform infrared (FTIR) analysis was performed on dried, pulverised outer scales and chamomile. Pure standards of polyphenols (apigenin, quercetin and caffeic acid) were also used for FTIR spectral comparison. Results and conclusions. Total hydroxycinnamic acids (THA), total flavonols (TFL), antioxidant activity (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and Fe(III) reducing antioxidant power (FRAP)), and inhibition of bovine serum albumin (BSA) by onion scale extract were measured in the initial, salivary, gastric and intestinal phases. Chamomile treatment increased THA, TFL, antioxidant (FRAP) and antiglycation activity (BSA method) in almost all in vitro digestion phases. Treating onions with chamomile water extract is an effective method for enriching biological waste, as confirmed by FTIR analysis. Enriched onion scales are a good source of bioaccessible polyphenols with high antioxidant (ABTS>85 % and FRAP>95 %) and moderate antiglycation activity (43–62 %). Novelty and scientific contribution. The enrichment of the phytochemical composition and biological potential of onions highlights the potential applications of this technique for health and nutritional purposes. Since the method does not require genetic modification but relies on natural absorption mechanisms and stress induction, it could become a valuable tool for enriching the nutritional and therapeutic composition of herbs. These results provide a foundation for future research, which should further elucidate the mechanisms of transmission, long-term effects, and potential industrial applications of this phenomenon.

Climate change is increasing flood frequency, exposing plants to severe stress. This study investigated the biostimulant-like effects of exogenous ferulic acid (FA; 1, 10, and 100 mg/L) on broccoli (Brassica oleracea var. cymosa) microgreens under regularly watered (RW) and flooded (F) conditions. Spectrophotometric, HPLC, and statistical analyses showed that all FA concentrations increased total phenolics and proanthocyanidins in flooded plants, while only 100 mg/L increased proanthocyanidins in RW plants. FA at 1 and 100 mg/L reduced soluble sugars in RW broccoli (18% reduction by both FA concentrations) and enhanced antioxidant capacity (measured by ferric reducing antioxidant power assay, FRAP) in flooded plants (8% and 11%, respectively). Only 10 mg/L FA lowered hydrogen peroxide in RW plants. Flooding significantly decreased glutathione (GSH) levels, but FA treatment doubled GSH concentration and restored its level in flooded broccoli, improving redox balance. FA also influenced individual polyphenols more strongly in RW plants, with notable increases in sinapic acid and kaempferol. Overall, FA enhanced antioxidant status and redox homeostasis under flooding stress, mainly by stimulating glutathione accumulation and phenylpropanoid metabolism. Its regulatory effects were strongly dependent on soil water conditions. These findings underscore the practical and agronomic potential of FA as an effective approach to enhance crop resilience under climate change.

With rising global temperatures, biostimulants might be a promising tool to alleviate plant stress and support adaptation. The potential of fresh (FBP) and lyophilized (LBP) banana peel aqueous extracts as biostimulants for protecting broccoli from high temperature (HT) stress was analyzed. Spectrophotometric and statistical analyses revealed that BP affected broccoli phytochemistry in a temperature-dependent manner. Under room temperature (RT), FBP and LBP decreased glucosinolates (−15% and −25%, respectively). Conversely, FBP increased flavonols and proanthocyanidins (141% and 202%, respectively). Under RT, LBP decreased sugars in broccoli (−27%). FBP had stronger effects at HT than at RT, further boosting phenolics (70%), flavonoids (89%), tannins (31%), and hydroxycinnamic acids (64%), and antioxidant capacity (FRAP) (10%). LBP also increased flavonoids (39%), flavonols (95%), and hydroxycinnamic acids (45%) under HT. Both FBP and LBP increased glucosinolates (47% and 46%, respectively) in HT-grown broccoli. HT significantly affected glucosinolates, decreased them in control plants, and increased them in BP-treated plants. All HT-grown plants had higher soluble sugars and lower hydrogen peroxide than RT-grown plants. Principal component analysis confirmed greater biochemical diversity under HT. Temperature–BP interaction significantly affected flavonoids and glucosinolates, highlighting the central role of environmental temperature in determining biostimulant outcomes. These findings suggest that global warming may markedly alter biostimulant efficacy and should be considered in their development.

This study investigated the influence of drying techniques such as convection hot-air drying, vacuum drying, and freeze drying with slow and flash pre-freezing on the total phenolic content and the profile of dominant phenolic compounds in cultivated blueberry (Vaccinium corymbosum L.). Although fresh blueberries exhibited higher total phenolic content (1350.85 mg GAE/100 g), total flavonol glycosides (66.20 mg/100 g), and total anthocyanins (218.23 mg/100 g) compared with dried samples, freeze-dried samples, particularly those subjected to flash pre-freezing, retained higher contents of these components in the dried material compared to other drying techniques. This could be attributed to the microstructural preservation of plant tissue during freeze drying. Furthermore, the study demonstrated that subsequent milling of freeze-dried samples, whether using a knife mill or a ball mill, also affects the availability of bioactive compounds in freeze-dried blueberry powders. The combination of flash pre-freezing followed by ball milling yielded the highest availability of bioactive components in the processed blueberry powder.

Thermal processing alters the nutritional and functional properties of vegetable food. In this study, using electrophoretic, spectrophotometric, and statistical analyses, we analyzed the effects of boiling, blanching, steaming, and blanching followed by pan-frying and air-frying on the concentration of bioactive compounds in kale and chard, and the biological effects of their extracts. In addition to analyzing the vegetable tissues, the residual water remaining after thermal processing was also examined to assess the nutritional potential of this often overlooked and typically discarded by-product. The residual cooking water had the highest antioxidant capacity, according to ABTS, DPPH, and FRAP assays (57.83% ± 18.16%, 33.58% ± 16.55%, and 81.58% ± 0.78% for kale and 74.53% ± 4.56%, 13.62% ± 7.34%, and 82.97% ± 0.44% for chard, respectively). Air-frying and cooking water contained the highest total phenolics (0.48 ± 0.17 mg GAE/g fw and 0.35 ± 0.06 mg GAE/g fw for kale and 0.88 ± 0.21 mg GAE/g fw and 0.80 ± 0.06 mg GAE/g fw for chard, respectively). Thermally processed chard had a higher concentration of oxidative marker H₂O₂ than kale. An inverse relationship between soluble sugars and H₂O₂ levels was observed. In kale, cooking processes caused the greatest reduction in soluble sugars, whereas in chard, this effect was most pronounced during blanching. Chard had more photosynthetic pigments than kale. Heat treatments caused more differences between kale samples than chard samples. Pan-frying best preserved chlorophylls, porphyrins, and carotenoids. According to both PC and HC analysis, the tissues of kale were clearly distinguishable from the water remaining after boiling/blanching/steaming kale. These results may help to optimize industrial processing conditions to better preserve bioactive compounds and create opportunities for the valorization of cooking by-products.

This study evaluates the antihyperlipidemic (pancreatic lipase inhibition assay), antiglycation (inhibition of bovine serum albumin glycation, BSA glycation), and antioxidant activity (ABTS, DPPH and FRAP assays) of ethanolic extracts from flowering parts of five widely distributed plant species in Croatia – Crocus heuffelianus Herb. (tepals), Nicotiana tabacum L. (petals), Malva sylvestris L. (petals), Calendula officinalis L. and Helianthus annuus L. (both sterile ligulate flowers). An in vitro -simulated system of human digestion was employed to assess the bioaccessibility of the selected phenolics and the stability of the extracts’ antioxidant, hypolipi demic, and antiglycation potential following each digestion phase. The concentrations of l-ascorbic acid, individual flavonoids, and phenolic acids were determined using RP-HPLC analysis. Principal component analysis revealed significant differences in the content of bioactive compounds and their biological activity among the investigated plant species. All original extracts exhibited high antioxidant capacity (> 70 %) in at least one assay, with N. tabacum and H. annuus demonstrating the strongest anti-oxidant capacity throughout digestion. H. annuus contained the highest levels of total identified phenolic acids, total identified phenols, and total identified compounds, while N. tabacum and C. heuffelianus exhibited the highest total flavonoid content. Among individual compounds, protocatechuic acid, quercetin, and ferulic acid significantly contributed to antioxidant activity. N. tabacum had the strongest antihyperlipidemic potential in the original extracts, as well as in the most digestion phases. Strong BSA glycation inhibition (70–100 %) was observed in all plant extracts across various digestion phases, with the exception of C. heuffelianus , which exhibited mode rate inhibitory effects. These findings suggest that the analyzed flower-derived plant materials, some of which are often considered agricultural waste, can serve as sustainable and valuable resources of bioactive compounds for functional food, dietary supplements, and pharmaceutical applications.

Vegetables are usually thermally processed before consumption to improve their flavor and safety. In this work, the effect of boiling (BO), blanching (BL), steaming (ST), air-frying (AF), and pan-frying (PF)on the nutritional value and bioactivity of broccoli (Brassica oleracea var. italica) heads was investigated, including a comparative analysis of the tissue and the cooking water remaining after the treatments. Using spectrophotometric methods, AF broccoli was found to have the highest levels (p ≤ 0.05) of hydroxycinnamic acids (1.58 ± 0.71 mg CAE/g fw), total glucosinolates (3.76 ± 2.09 mg SinE/g fw), carotenoids (6.73 ± 2.89 mg/kg fw), and lycopene (0.91 ± 0.19 mg/kg fw). Steamed and AF broccoli had the highest total phenolics (0.72 ± 0.12 mg GAE/g fw and 0.65 ± 0.15 mg GAE/g fw, respectively; p ≤ 0.05). ST broccoli also had the highest levels of soluble sugars (11.04 ± 2.45 mg SucE/g fw) and total tannins (0.46 ± 0.19 mg GAE/g fw). The water remaining after cooking broccoli (BOW) had the highest total flavonoids (2.72 ± 0.59 mg QE/g fw) and antioxidant capacity (ABTS and FRAP, 57.57 ± 18.22% and 79.34 ± 3.28%, respectively; p ≤ 0.05). The DPPH assay showed that AF (36.12 ± 15.71%) and ST (35.48 ± 2.28%) had the strongest antioxidant potential. DNA nicking assay showed that BOW and BLW were the most effective in preserving plasmid DNA supercoiled form (99.51% and 94.81%, respectively; p ≤ 0.05). These results demonstrate that thermal processing significantly affects the phytochemical composition and functional properties of broccoli, with steaming and air-frying generally preserving the highest nutritional quality. Additionally, cooking water, often discarded, retains high levels of bioactive compounds and exhibits strong antioxidant and DNA-protective effects. To the best of our knowledge, this is the first study to investigate how different thermal processing techniques of vegetables influence their ability to protect plasmid DNA structure. Furthermore, this is the first study to compare the DNA-protective effects of broccoli tissue extracts and the water remaining after cooking broccoli.

Purslane (Portulaca oleracea L.) is a plant recognized as a valuable source of nutrients and bioactive compounds such as omega-3 fatty acids, antioxidants, vitamins, and minerals. This study investigates the effects of grinding techniques (knife, ball, and planetary ball mill) on the properties of purslane powder (surface microstructure, particle size distribution, and color), their influence on the phenolic content in the extracts of purslane powder before and after in vitro simulated digestion process, and the antioxidant activity of the purslane extracts. The results showed that applied grinding techniques affected the particle size distribution and surface morphology of the powder, which in turn influenced the gastrointestinal stability of the dominant phenolic compounds in purslane powder extracts. The powder obtained via ball milling, characterized by the highest proportion of fine particles (x < 100 µm), showed the highest content of total phenolics (656 mg GAE/L). Ball milling resulted in high preservation of the dominant phenolic acids in the powder extract after simulated gastric and intestinal digestion (83.55% and 69.42%) and high free radical scavenging activity (DPPH and ABTS) and ferric reducing power (FRAP). The results obtained emphasize the nutritional and biological benefits of purslane in the form of a fine powder.