Boosting nutritional quality of Urtica dioica L. to resist climate change.

Introduction: More than ever, traditional agricultural practices need a shift towards more resilient, sustainable, modern and adaptable practices that benefit the health of the planet and people. Today's consumers are constantly on the lookout for novel, highly nutritious foods that have a positive impact on their overall health and well-being. Nettle (Urtica dioica L.) is gaining recognition not only as a popular medicinal plant, but also as a desirable green leafy vegetable rich in phytonutrients. As it is difficult and even expensive to control the quality standards of wild-collected plants, the implementation of sustainable cultivation methods, especially hydroponics, with effective greenhouse management could be a possible solution to obtain a standardized product with high nutritional value. Therefore, the aim of this study was to investigate the effects of four nutrient solutions differing in the content of macro- and micronutrients (especially nitrogen, potassium, calcium, magnesium and iron) and two consecutive cuts on the number of leaves, yield, nitrate and mineral content and the content of specialized metabolites of stinging nettle from a floating hydroponic system. Methods: Nettle plants were cultivated in a hydroponic system using the floating hydroponics technique. The two-factorial experiment was performed with nutrient solution and consecutive cuts as factors. Results: The highest yield (2.49 kg/m2) was achieved after the 1st cut with plants cultivated in the nutrient solution with higher nutrient concentration. All tested nutrient solutions resulted in high levels of minerals and bioactive compounds in the plant material (ascorbic acid content of 102.30 mg/100 g fw and total phenolics content of 465.92 mg GAE/100 g fw), confirming floating hydroponics as a sustainable approach for cultivating nettle with enhanced nutritional value and antioxidant potential. Conclusion: It is important to highlight that the nutrient solution with the lowest nutrient composition yielded the highest concentrations of calcium (5.54%) and iron (180.67 mg/kg dw). Furthermore, it exhibited elevated levels of specific phenolic compounds, including caffeoylmaleic acid, ellagic acid, ferulic acid, naringin, and rutin trihydrate. Notably, this solution demonstrated the lowest nitrate content (4225.33 mg/kg fw) in the plant material. Therefore, it can be recommended as a preferable formulation for hydroponic nettle cultivation.

Influence of Nutrient Deprivation on the Antioxidant Capacity and Chemical Profile of Two Diatoms from Genus Chaetoceros.

The limited availability of phosphate, nitrogen and silicon in the growth media affects the growth, cellular processes, and metabolism of diatoms. Silicon deficiency primarily affects diatom morphology, while phosphate deficiency reduces the production of nucleic acids and phospholipids. Differences in pigment and protein composition are mainly due to nitrogen deficiency. In this study, Chaetoceros socialis and Chaetoceros costatus were cultured under phosphate, nitrogen, and silicon deprivation conditions. The diatom biomass was collected during the stationary growth phase and extracted with 70% ethanol under ultrasonication. The chemical profiles of the extracts were analyzed by high-performance liquid chromatography with high-resolution mass spectrometry with electrospray ionisation (UHPLC-ESI-HRMS), while the antioxidant capacity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and oxygen radical absorbance capacity (ORAC) assays. Pigments, fatty acids, sterols, and derivatives were detected in both species. The total phenolic content in the extracts ranged from 46.25 ± 1.08 to 89.38 ± 6.21 mg of gallic acid equivalent (GAE)/L and from 29.58 ± 1.08 to 54.17 ± 1.18 mg GAE/L. for C. costatus and C. socialis, respectively. Antioxidant activity was higher in C. costatus extracts, especially those obtained from nitrogen-deprived media. The results of this study contribute to the existing knowledge and the ongoing efforts to overcome application and commercialization barriers of microalgae for wide-ranging potential in different industries.

Vinegar-Preserved Sea Fennel: Chemistry, Color, Texture, Aroma, and Taste.

The aim of this study was to produce non-fermented preserved sea fennel leaves in different pickle juices prepared with apple cider vinegar, wine vinegar and alcoholic vinegar, and to compare their chemical parameters (pH, titratable acidity and salt content), organoleptic properties (color and texture parameters; volatile aromatic compound profiles) and sensory attributes. The pH of the samples ranged from 3.49 to 3.64, the lowest being in the alcoholic vinegar sample and the highest being in the wine vinegar sample, while the titratable acidity and salinity were higher in the alcoholic vinegar pickle juice than those in the other two samples. The volatile aromatic compounds of the samples were also detected. The reddish color of the wine vinegar negatively affected the sea fennel color parameters (L* and b*), and was also negatively evaluated by the panelists, while the alcoholic vinegar maximally preserved the green tones of the leaf (a*). Firmness influences the quality perceived by consumers and was therefore also tested as one of the most important parameters for evaluating the textural and mechanical properties of the different products. All sensory parameters of the sea fennel preserved in alcoholic vinegar, namely color, texture, taste, aroma and overall impression, were given the highest scores, while the sample preserved in wine vinegar received the lowest scores. The intense aroma of the wine vinegar was described as a negative characteristic (off-flavor) of the sample.

Innovative Strategy for Aroma Stabilization Using Green Solvents: Supercritical CO2 Extracts of Satureja montana Dispersed in Deep Eutectic Solvents.

The aim of this work was to establish the potential of natural deep eutectic solvents (NADES) for the stabilization of aroma volatile organic compounds from a natural source. Satureja montana was used as a source of volatile components, as it is rich in terpenes of great commercial and biological importance, such as carvacrol, thymol, and thymoquinone, among others. Supercritical CO2 was used to extract the lipophilic fraction of S. montana, which was further directly dispersed in NADES. The stabilizing capacity of seven different NADES based on betaine and glycerol was analyzed. The stability of the components in NADES was monitored by analyzing the headspace profile during 6 months of storage at room temperature. The changes in the headspace profile over time were analyzed by using different statistical and chemometric tools and the Wilcoxon matched pair test. It was determined that alterations over time occurred such as degradation and oxidation, and they were the most prominent in the control. In addition, the indicator of decreased stability of the control was the formation of the new compounds that could compromise the quality of the product. In the stabilized NADES samples, the changes were significantly less prominent, indicating that the NADES had a stabilizing effect on the volatile compounds. According to Wilcoxon matched pair test, the most efficient stability was achieved by using betaine/ethylene glycol, glycerol/glucose, and betaine/sorbitol/water. Therefore, by applying two green solvents, a sustainable approach for obtaining pure and high-quality S. montana extracts with extended stability at room temperature was established.

Seasonal Monitoring of Volatiles and Antioxidant Activity of Brown Alga Cladostephus spongiosus.

Cladostephus spongiosus was harvested once a month during its growing season (from May to August) from the Adriatic Sea. Algal volatile organic compounds (VOCs) were obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) and analysed by gas chromatography and mass spectrometry (GC-MS). The effects of air drying and growing season on VOCs were determined. Two different extraction methods (ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE)) were used to obtain ethanolic extracts of C. spongiosus. In addition, the seasonal antioxidant potential of the extracts was determined, and non-volatile compounds were identified from the most potent antioxidant extract. Aliphatic compounds (e.g., pentadecane) were predominantly found by HS-SPME/GC-MS. Hydrocarbons were more than twice as abundant in the dry samples (except in May). Aliphatic alcohols (e.g., hexan-1-ol, octan-1-ol, and oct-1-en-3-ol) were present in high percentages and were more abundant in the fresh samples. Hexanal, heptanal, nonanal, and tridecanal were also found. Aliphatic ketones (octan-3-one, 6-methylhept-5-en-2-one, and (E,Z)-octa-3,5-dien-2-one) were more abundant in the fresh samples. Benzene derivatives (e.g., benzyl alcohol and benzaldehyde) were dominant in the fresh samples from May and August. (E)-Verbenol and p-cymen-8-ol were the most abundant in dry samples in May. HD revealed aliphatic compounds (e.g., heptadecane, pentadecanal, (E)-heptadec-8-ene, (Z)-heptadec-3-ene), sesquiterpenes (germacrene D, epi-bicyclosesquiphellandrene, gleenol), diterpenes (phytol, pachydictyol A, (E)-geranyl geraniol, cembra-4,7,11,15-tetraen-3-ol), and others. Among them, terpenes were the most abundant (except for July). Seasonal variations in the antioxidant activity of the ethanolic extracts were evaluated via different assays. MAE extracts showed higher peroxyl radical inhibition activity from 55.1 to 74.2 µM TE (Trolox equivalents). The highest reducing activity (293.8 µM TE) was observed for the May sample. Therefore, the May MAE extract was analysed via high-performance liquid chromatography with high-resolution mass spectrometry and electrospray ionisation (UHPLC-ESI-HRMS). In total, 17 fatty acid derivatives, 9 pigments and derivatives, and 2 steroid derivatives were found. The highest content of pheophorbide a and fucoxanthin, as well as the presence of other pigment derivatives, could be related to the observed antioxidant activity.

Alfalfa, Cabbage, Beet and Fennel Microgreens in Floating Hydroponics-Perspective Nutritious Food?

Microgreens are young plants of various vegetables, medicinal and aromatic plants, cereals and edible wild plants that were first associated with nouvelle cuisine as decoration in dishes due to their attractive appearance and strong flavor. Recently, they have become more sought after in the market due to their high nutritional value. This is due to the growing interest of consumers in a healthy lifestyle that includes a varied diet with emphasis on fresh, functional foods. Nowadays, commercial production of microgreens is shifting to modern hydroponic systems due to their numerous advantages, such as accelerated plant growth and biomass production, earlier harvesting, and more production cycles that positively affect yield and chemical composition. Therefore, the aim of this study was to determine the content of specialized metabolites and antioxidant capacity of hydroponically grown alfalfa (Medicago sativa) cv. 'Kangaroo', yellow beet (Beta vulgaris var. conditiva) cv. 'Yellow Lady', red cabbage (Brassica oleracea L. var. rubra) cv. 'Red Carpet', and fennel (Foeniculum vulgare) cv. 'Aganarpo' microgreens. The highest content of total phenols (408.03 mg GAE/100 g fw), flavonoids (214.47 mg GAE/100 g fw), non-flavonoids (193.56 mg GAE/100 g fw) and ascorbic acid (74.94 mg/100 g fw) was found in fennel microgreens. The highest content of all analyzed chlorophyll pigments (Chl_a 0.536 mg/g fw, Chl_b 0.248 mg/g fw, and TCh 0.785 mg/g fw) was found in alfalfa microgreens. However, in addition to alfalfa, high levels of chlorophyll a (0.528 mg/g fw), total chlorophyll (0.713 mg/g fw) and the highest level of total carotenoids (0.196 mg/g fw) were also detected in fennel microgreens. The results suggest that microgreens grown on perlite in floating hydroponics have high nutritional potential as a functional food important for human health and therefore could be recommended for daily diet.

How to Increase the Nutritional Quality of Stinging Nettle Through Controlled Plant Nutrition§.

Research background: As food production faces major challenges, modern agricultural practices are increasingly focused on conserving resources, reducing negative environmental impacts and sustainably producing food with a high content of health-promoting phytochemicals. During production, many factors can affect the quality and chemical composition of a final food product. Proper selection of cultivating conditions, especially a balanced nutrition, can significantly increase nutritional value and result in foods with strong biological and functional properties. Stinging nettle is a rich source of minerals, vitamins, pigments, phenols and other bioactive compounds and can be consumed as a green leafy vegetable with beneficial effects on human health. Therefore, the aim of this study is to determine the nutritional quality and antioxidant capacity of stinging nettle leaves under the influence of different nutrient solution (NS) treatments and three harvest cycles. Experimental approach: The experiment was conducted in a floating hydroponic system in which treatments with different nutrient solutions were applied and three harvest cycles were carried out. After each harvest, the following treatments were applied: treatment 1 - depletion of nutrient solution by adding water, treatment 2 - supplementation of nutrient solution by adding initial nutrient solution and treatment 3 - correction of nutrient solution by adding nutrients. Among the bioactive compounds, minerals, ascorbic acid, phenols and photosynthetic pigments content, as well as antioxidant capacity were analysed spectrophotometrically, while individual phenols were determined by liquid chromatography. Results and conclusions: Different nutrition solution treatments and the number of harvest cycles had a significant effect on the content of the analysed bioactive compounds. The highest mass fraction (on fresh mass basis) of total phenols expressed as gallic acid equivalents (377.04 mg/100 g), total flavonoids expressed as catechol equivalents (279.54 mg/100 g), ascorbic acid (112.37 mg/100 g) and pigments (total chlorophylls 1.84, and total carotenoids 0.36 mg/g) as well as the highest antioxidant capacity expressed as Trolox equivalents (35.47 µmol/g) were recorded in the samples supplemented with nutrient solution (treatment NS2) and analysed after the third harvest. Novelty and scientific contribution: This is the first time that stinging nettle leaves have been produced in a floating hydroponic system by controlled plant nutrition. We have set this type of nutritional manipulation with multiple harvest cycles as an innovative technique for the production of novel food with improved nutritional value that can be consumed as green leafy vegetables.

A Plant Worthy of Further Study-Volatile and Non-Volatile Compounds of Portenschlagiella ramosissima (Port.) Tutin and Its Biological Activity.

New and detailed data are presented on the phytochemical composition of the volatile and non-volatile organic compounds of the Mediterranean endemic species Portenschlagiella ramosissima (Port.) Tutin. Both the essential oil and hydrosol were obtained from the air-dried plant by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The volatile compounds from the fresh and air-dried plants and from the hydrosol were isolated for the first time by headspace solid-phase microextraction using two fibres of different polarity. The benzene derivative group was the predominant group in all samples, with myristicin being the most abundant component of all. The non-volatile compounds of the methanol extract were analyzed by ultra-high-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionisation, and three flavonoid glycosides, one anthocyanidin glycoside, and lipid derivatives were detected. Both the chemical composition and biological activities of this plant have been described in a very limited number of publications, making it an interesting source for further study. The antiphytoviral activity of the essential oil and hydrosol showed that both extracts significantly reduced the number of lesions on the leaves of local host plants infected with tobacco mosaic virus. Moderate antiproliferative activity of the methanol extract was detected in three cancer cell lines, cervical cancer cell line, human colon cancer cell line and human osteosarcoma cell line, using the MTS-based cell proliferation assay. Based on the results, we highlight this plant as a new source of bioactive compounds and natural phytotherapeutic agent that deserves further investigation.

Volatile Organic Compound Profiles of Cystoseira corniculata (Turner) Zanardini 1841 and Ericaria amentacea (C.Agardh) Molinari and Guiry 2020 (ex. Cystoseira amentacea (C.Agardh) Bory de Saint-Vincent, 1832).

The volatile organic compounds (VOCs) of fresh (FrCC) and air-dried (DrCC) Cystoseria corniculata and fresh (FrEA) and air-dried (DrEA) Ericaria amentacea from the Adriatic Sea were investigated by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) and analysed by gas chromatography and mass spectrometry (GC-MS). In HS-FrCC and HS-DrCC, aliphatic compounds were dominant, with decan-5-ol as the most abundant in HS-FrCC, but in HS-DrCC pentadecane dominated. Monoterpenes (ß-cyclocitral, ß-citral, and ß-cyclohomocitral) and sesquiterpenes (cubenol) were abundant in HS-FrCC. Notable differences between fresh and air-dried samples were found for benzene derivatives. Fatty acids and their derivatives were the most abundant in HD-FrCC and HD-DrCC. In HS-FrEA and HS-DrEA, saturated aliphatic compounds as well as unsaturated aliphatic compounds (particularly hexan-1-ol and (Z)-hex-3-en-1-ol) predominantly showed decrements after drying. Pentadecane, heptadecane, pentadecanal, and hexan-1-ol were predominant in HD-FrEA, and their percentage decreased in HD-DrEA. The percentage of monoterpenes decreased after drying, but the percentages of diterpenes and especially sesquiterpenes increased. δ-Selinene was the major terpene and the most abundant in HD-DrEA. A significant increment after drying could be noticed for fatty acids and their derivatives. The great diversity of identified VOCs among these two macroalgae supports their different botanical classifications.

Edible Flower Species as a Promising Source of Specialized Metabolites.

Eating habits are changing over time and new innovative nutrient-rich foods will play a great role in the future. Awareness of the importance of a healthy diet is growing, so consumers are looking for new creative food products rich in phytochemicals, i.e., specialized metabolites (SM). The consumption of fruits, vegetables and aromatic species occupies an important place in the daily diet, but different edible flower species are still neglected and unexplored. Flowers are rich in SM, have strong antioxidant capacities and also possess significant functional and biological values with favorable impacts on human health. The main aim of this study was to evaluate the content of SM and the antioxidant capacities of the edible flower species: Calendula officinalis L. (common marigold), Tagetes erecta L. (African marigold), Tropaeolum majus L. (nasturtium), Cucurbita pepo L. convar. giromontiina (zucchini) and Centaurea cyanus L. (cornflower). The obtained results showed the highest content of ascorbic acid (129.70 mg/100 g fw) and anthocyanins (1012.09 mg/kg) recorded for cornflower, phenolic compounds (898.19 mg GAE/100 g fw) and carotenoids (0.58 mg/g) for African marigold and total chlorophylls (0.75 mg/g) for common marigold. In addition to the esthetic impression of the food, they represent an important source of SM and thus can have a significant impact if incorporated in the daily diet.

Detailed Chemical Prospecting of Volatile Organic Compounds Variations from Adriatic Macroalga Halopteris scoparia.

The present study aimed to isolate volatile organic compounds (VOCs) from fresh (FrHSc) and air-dried (DrHSc) Halopteris scoparia (from the Adriatic Sea) by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) and to analyse them by gas chromatography and mass spectrometry (GC-MS). The impact of the season of growth (May-September) and air-drying on VOC composition was studied for the first time, and the obtained data were elaborated by principal component analysis (PCA). The most abundant headspace compounds were benzaldehyde, pentadecane (a chemical marker of brown macroalgae), and pentadec-1-ene. Benzaldehyde abundance decreased after air-drying while an increment of benzyl alcohol after drying was noticed. The percentage of pentadecane and heptadecane increased after drying, while pentadec-1-ene abundance decreased. Octan-1-ol decreased from May to September. In HD-FrHSc, terpenes were the most abundant in June, July, and August, while, in May and September, unsaturated aliphatic compounds were dominant. In HD-DrHSc terpenes, unsaturated and saturated aliphatic compounds dominated. (E)-Phytol was the most abundant compound in HD-FrHSc through all months except September. Its abundance increased from May to August. Two more diterpene alcohols (isopachydictyol A and cembra-4,7,11,15-tetraen-3-ol) and sesquiterpene alcohol gleenol were also detected in high abundance. Among aliphatic compounds, the dominant was pentadec-1-ene with its peak in September, while pentadecane was present with lower abundance. PCA (based on the dominant compound analyses) showed distinct separation of the fresh and dried samples. No correlation was found between compound abundance and temperature change. The results indicate great seasonal variability of isolated VOCs, as well among fresh and dried samples, which is important for further chemical biodiversity studies.

Application of Ultrasound as Clean Technology for Extraction of Specialized Metabolites From Stinging Nettle (Urtica dioica L.).

Nettle is a highly valued medicinal plant that is still largely neglected, both in terms of nutrition and use for pharmacological purposes. Tinctures, i.e., alcoholic extracts, are becoming increasingly popular nettle products, mainly because they allow better availability of phytochemicals and their stability over a longer period of time. The production of alcoholic extracts is a chemically demanding process that is still usually carried out using conventional techniques, which have numerous drawbacks. The use of green technologies such as ultrasound-assisted extraction (UAE), which is characterized by high efficiency of phytochemical extraction, shorter treatment time, and a much lower environmental footprint, is a suitable and sustainable solution. Therefore, the aim of this study is to determine the influence of the extraction method, conventional and ultrasound (by varying two ultrasound equipment systems), time and ethanol concentration on the extraction of specialized metabolites from nettle powder. Ultrasonic extraction using a probe system significantly contributed to increase the ascorbic acid yield, polyphenolic compounds, and antioxidant capacity of nettle extracts compared to conventional extraction. In addition, when a probe system was used during UAE, significantly less time was required for isolation of individual specialized metabolites compared to ultrasonic extraction in the bath. Ethanol concentration (50 and 80% v/v) also proved to be an important factor in the efficiency of extraction of specialized metabolites, with 80% ethanol being more effective for the isolation of ascorbic acid and pigment compounds (chlorophyll and carotenoids), while 50% v/v for the extraction of polyphenolic compounds. It can be concluded that extraction with the ultrasonic probe system is much more efficient in obtaining higher yields of specialized metabolites from nettle powder in a shorter time (average process duration 5-10 min) both compared to UAE in the bath and classical extraction. However, optimization of the key factors of time, solvent type, and ultrasonic power is necessary to maintain the nutritional quality of the nettle extract in order to obtain a final product with a high specialized metabolites content, antioxidant capacity, and functional value. The future application of alcoholic nettle extracts is based on the fact that these products have significant potential as functional foods and pharmacological preparations for the treatment of a number of but also to strengthen the immune system, mainly due to the rich nutritional composition and high content of various specialized metabolites. The prepared extracts can be safely taken orally by diluting the tinctures with water immediately before ingestion.

Supercritical CO2 Extract from Microalga Tetradesmus obliquus: The Effect of High-Pressure Pre-Treatment.

High-pressure pre-treatment followed by supercritical carbon dioxide (ScCO2) extraction (300 bar, 40 °C) was applied for the attainment of the lipophilic fraction of microalga Tetradesmus obliquus. The chemical profile of supercritical extracts of T. obliquus was analyzed by ultra-high-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). Moreover, the impact of ScCO2 on the microbiological and metal profile of the biomass was monitored. The application of the pre-treatment increased the extraction yield approximately three-fold compared to the control. In the obtained extracts (control and pre-treated extracts), the identified components belonged to triacylglyceroles, fatty acid derivatives, diacylglycerophosphocholines and diacylglycerophosphoserines, pigments, terpenes, and steroids. Triacylglycerols (65%) were the most dominant group of compounds in the control extract. The pre-treatment decreased the percentage of triacylglycerols to 2%, while the abundance of fatty acid derivatives was significantly increased (82%). In addition, the pre-treatment led to an increase in the percentages of carotenoids, terpenoids, and steroids. Furthermore, it was determined that ScCO2 extraction reduced the number of microorganisms in the biomass. Considering its microbiological and metal profiles, the biomass after ScCO2 can potentially be used as a safe and important source of organic compounds.

In Vivo and In Vitro Antioxidant Activity of Less Polar Fractions of Dasycladus vermicularis (Scopoli) Krasser 1898 and the Chemical Composition of Fractions and Macroalga Volatilome.

The present research is a comprehensive investigation of Dasycladus vermicularis (Scopoli) Krasser 1898 from the Adriatic Sea (Croatia) regarding volatilome-volatile organic compounds (VOCs, mostly nonpolar compounds) and less polar nonvolatile compounds for the first time. Headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) were used showing the great volatilome variability among fresh (HS-FrDV and HD-FrDV) and dried (HS-DrDV and HD-DrDV) samples after GC-MS analysis. Aromatic aldehydes were dominant in both fresh and air-dried HS samples with benzaldehyde as the most abundant in fresh samples and decreasing 2.7-3.7 times after drying together with 2-phenylbut-2-enal that was not present after drying. Aliphatic compounds (unsaturated hydrocarbons in HS-FrDV; saturated hydrocarbons in HS-DrDV) were also present. C11-hydrocarbons (dictyopterpene C' and dictyopterpene D') were detected in HS-FrDV. (E)-Phytol was the most dominant compound in HD-FrDV and HD-DrDV. Diterpene alcohols (cembra-4,7,11,15-tetraen-3-ol and (Z)-falcarinol) and sesquiterpene alcohol, cubenol, were dominant in HD-FrDV, and their abundance decreased after drying. C13-norisoprenoides (α-ionone and ß-ionone) increased after drying. Aliphatic compounds were present in both HD-FrDV and HD-DrDV samples. The less polar nonvolatile compounds in the obtained fractions F3 and F4 were analysed and identified by UHPLC-ESI(+)-HRMS. Identified compounds belonged to a group of pigments (7 compounds), fatty acid derivatives (13 compounds), as well as steroids and terpenes (10 compounds). Porphyrin-based compounds (C55H74N4O5-7), xanthophylls, sphingolipid compounds, fatty acid amides, and phytosterols represented the majority of identified compounds. By implementing both in vitro and in vivo assays for antioxidant activity determination, F3 showed a higher activity than F4. Inhibitory concentrations (IC50) for F3 and F4 were 498.00 ± 0.01 µg/mL and 798.00 ± 0.81 µg/mL, respectively, while a 1.5-fold reduction in the ROS level was observed after pre-treatment of zebrafish larvae with 45 µg/mL of F3.

Seasonal Variability of Volatilome from Dictyota dichotoma.

Dictyotaceae, the large family of brown algae with the genus Dictyota as the richest one among them, produce a significant number of secondary metabolites, like diterpenes. The aim of this study was to investigate the variations in the composition of the volatile organic compounds (VOCs) of the brown alga Dictyota dichotoma collected from the Adriatic Sea. For the first time, both seasonal changes and the impact of air drying were examined. Headspace solid-phase microextraction (HS-SPME) on two fibres with different polarities and hydrodistillation (HD), followed by gas chromatography and mass spectrometry (GC-MS) analysis, was performed on both fresh (FrDd) and air-dried (DrDd) D. dichotoma. The major compounds of HS-FrDd were pentadecane and oct-1-en-3-ol. The percentage of pentadecane in HS-DrDd was increased up to 7.8 times in comparison with HS-FrDd. Principal component analysis (PCA) identified differences between the variability of data among fresh and dried samples over months and clearly dissociated the fresh May samples from the others in the HS-SPME results. The most abundant group of VOCs in HD were terpenes, with diterpenes isopachydictyol A and cembra-4,7,11,15-tetraen-3-ol as the major compounds. Diterpene pachydictyol A was also found and among sesquiterpenes and gleenol was the most abundant. Based on the dominant compound analyses, the PCA showed distinct separation of the fresh and dried samples, indicating similarities between the samples and allowing the establishment of typical VOCs significant for the chemotaxonomy of D. dichotoma.

Nettle Cultivation Practices-From Open Field to Modern Hydroponics: A Case Study of Specialized Metabolites.

Conventional agricultural production faces numerous challenges due to the pronounced effects of climate change, particularly global warming, and drought more than ever before in history, with the primary concern being to produce adequate yields and high-quality, nutritious plant material. Likewise, people are increasingly looking for new sources of food and are becoming aware of the importance of a varied diet and its connection to health. In this sense, stinging nettle (Urtica dioica L.) stands out as a valuable species that is neglected as a food source, as it has a significant content of specialized metabolites, and thus has an extremely high potential for use both nutritionally and pharmacologically, but is still traditionally collected from natural habitats, so it can be of questionable quality and undefined chemical composition. Therefore, sustainable agricultural practices are increasingly shifting to modern hydroponic cultivation methods in greenhouses. The advantage lies in the easier management and control of a number of factors during cultivation (air temperature and relative humidity, balanced and rational fertilization, minimization of nitrate uptake, etc.), ensuring better conditions for the growth and development of nettle according to its needs. The aim of this review is to give an overview of the technology of stinging nettle cultivation in the field and to show the possibilities of cultivation with modern hydroponic techniques to obtain a final product of consistent and uniform quality, high content of specialized metabolites and significant nutritional value. Research on this topic is still sparse but will certainly increase in the future. Therefore, this review provides all the necessary data for such future studies.

Bioprospecting of Less-Polar Fractions of Ericaria crinita and Ericaria amentacea: Developmental Toxicity and Antioxidant Activity.

Ericaria crinita and Ericaria amentacea from the Adriatic Sea (Croatia) were investigated with respect to the presence of less-polar compounds for the first time after fractionation by solid-phase extraction (SPE). The composition of less-polar fractions of freeze-dried E. crinita (FdEc) and E. amentacea (FdEa) were analyzed by high-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). The major identified compounds were: amides of higher aliphatic acids (palmitoleamide, linoleamide, palmitamide, oleamide and erucamide) and related compounds, carotenoid (fucoxanthin), chlorophyll derivatives (pheophytin a and b and their derivatives) and higher terpenes (loliolide, isoamijiol with its oxidation product), ß-stigmasterol and (3ß,6α)-14-methylergosta-8,24(28)-diene-3,6-diol). The toxic effects observed on the less-polar fractions obtained from Ericaria species on zebrafish Danio rerio embryos could be associated with the high abundance of all five detected amides. The antioxidant activity of the fractions was evaluated by means of five independent assays, including the reduction of the radical cation (ABTS), the oxygen radical absorbance capacity (ORAC), ferric-reducing antioxidant power (FRAP), the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay and the Folin-Ciocalteu method. A higher antioxidant activity of E. amentacea in comparison to that of the E. crinita fractions was found with IC50 concentrations of 0.072 and 1.177 mg/mL, respectively. The correlation between the activity and the chemical composition revealed that the synergistic effect of different compounds impacted their antioxidant response.

Plant Response to Mechanically-Induced Stress: A Case Study on Specialized Metabolites of Leafy Vegetables.

Plants have evolved various adaptive mechanisms to environmental stresses, such as sensory mechanisms to detect mechanical stimuli. This plant adaptation has been successfully used in the production practice of leafy vegetables, called mechanical conditioning, for many years, but there is still a lack of research on the effects of mechanically-induced stress on the content of specialized metabolites, or phytochemicals with significant antioxidant activity. Therefore, the aim of this study was to determine the content of specialized metabolites and antioxidant capacity of lettuce and green chicory under the influence of mechanical stimulation by brushing. Mechanically-induced stress had a positive effect on the content of major antioxidants in plant cells, specifically vitamin C, total phenols, and flavonoids. In contrast, no effect of mechanical stimulation was found on the content of pigments, total chlorophylls, and carotenoids. Based on the obtained results, it can be concluded that induced mechanical stress is a good practice in the cultivation of leafy vegetables, the application of which provides high quality plant material with high nutritional potential and significantly higher content of antioxidants and phytochemicals important for human health.

Less Polar Compounds and Targeted Antioxidant Potential (In Vitro and In Vivo) of Codium adhaerens C. Agardh 1822.

Codium adhaerens from the Adriatic Sea (Croatia) was comprehensively investigated regarding less polar compounds for the first time. Although there are several phytochemical studies on C. adhaerens from other regions, this is the first report on volatile organic compounds (VOCs) from fresh (FrCa) and air-dried (DrCa) samples. The novelty is also related to its targeted antioxidant potential in vitro and in vivo. The main aims were to: (a) identify and compare VOCs of FrCa and DrCa obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD); (b) determine fatty acid (FA) composition of freeze-dried sample (FdCa); (c) determine the composition of less polar fractions of FdCa by high-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionisation (UHPLC-ESI-HRMS); and (d) comprehensively evaluate the antioxidant activity of the fractions by four in vitro assays and in vivo zebrafish model (including embryotoxicity). Significant changes of VOCs were found after air drying. ω6 FAs were present in higher content than ω3 FAs indicating C. adhaerens as a good source of dietary polyunsaturated FAs. The results obtained in vivo correlate well with in vitro methods and both fractions exerted similar antioxidative responses which is in agreement with the high abundance of present biomolecules with known antioxidant properties (e.g., fucoxanthin, pheophytin a, and pheophorbide a). These results suggest that C. adhaerens might be a potent source of natural antioxidants that could be further used in the research of oxidative stress-related diseases.

Ultrasound as a Promising Tool for the Green Extraction of Specialized Metabolites from Some Culinary Spices.

Spices are a popular food of plant origin, rich in various phytochemicals and recognized for their numerous properties. The aim of the study was to evaluate the antioxidant and antimicrobial activity, as well as the content of specialized metabolites, of aqueous extracts of three spice species--garlic (Allium sativum L.), ginger (Zingiber officinalle L.) and turmeric (Curcuma longa L.)--prepared by green extraction methods. Ultrasound treatment increased the chromaticity parameter b value of turmeric and ginger extracts, thus indicating a higher yellow color predominantly due to curcuminoids characteristic of these species. Ultrasound-assisted extraction significantly increased the content of total soluble solids, phenolic compounds, total carotenoids and vitamin C. The temperature of the system was also an important factor, with the highest (70 °C) conditions in ultrasound-assisted extraction having a positive effect on thermolabile compounds (vitamin C, phenolics, total carotenoids). For example, turmeric extract treated with ultrasound at 70 °C had up to a 67% higher vitamin C content and a 69.4% higher total carotenoid content compared to samples treated conventionally at the same temperature, while ginger extracts had up to 40% higher total phenols. All different concentrations of spice extracts were not sufficient for complete inhibition of pathogenic bacterial strains of Salmonella, L. monocytogenes and S. aureus; however, only garlic extracts had an effect on slowing down the growth and number of L. monocytogenes colonies. Spice extracts obtained by ultrasonic treatment contained a significantly higher level of bioactive compounds and antioxidant capacity, suggesting that the extracts obtained have significant nutritional potential and thus a significant possibility for phytotherapeutic uses.