Formulacije s limunovim sokom moduliraju dostupnost fitokemikalija špinata u in vitro modelu probave

Research background. Citrus limon (L.) Burm lemon juice is rich in many important natural chemical components (flavonoids, citric acid and vitamin C) and its use in traditional medicine is well known. Formulations of lemon juice with fruit polyphenols in beverages have been investigated, but there is very little information about their ability to modulate the digestive behaviour of polyphenols. The goal of this study is to determine the stability and digestive availability of spinach (Spinacia oleracea L.) polyphenols by adding different volume fractions of lemon juice (0, 2, 5, 10 and 20%) during in vitro digestion. Experimental approach. The content of polyphenols and other abundant compounds including nitrates, oxalic acid and l-ascorbic acid in spinach formulation with various volume fractions of lemon juice were measured in predigested and digested samples using in vitro human digestion model. Antioxidant and α-amylase inhibitory activities of spinach lemon juice formulation were also measured. Results and conclusions. The highest increases in total polyphenols, total flavonoids, total phenolic acids, oxalic acid and nitrate content were noted in predigested and almost all digested spinach samples formulated with the highest volume fraction of lemon juice. In the same sample, the content of individual compounds significantly increased after salivary (l-ascorbic acid), initial (p-coumaric acid) and intestinal (quercetin) phase of digestion. High bioaccessibility of polyphenols and l-ascorbic acid in all phases of digestion was observed in almost all spinach lemon juice formulations, with the exception of nitrates in gastric and intestinal phases and oxalic acid in the intestinal phase, which had moderate bioaccessibility. Novelty and scientific contribution. For the first time the stability and digestive availability of spinach polyphenols, oxalic acid, nitrates and l-ascorbic acid were tested with the addition of different volume fractions of lemon juice. The pH of lemon juice and its l-ascorbic acid content increase the stability and availability of polyphenols in spinach lemon juice formulation during in vitro digestion. Antioxidant and α-amylase inhibitory activities increase in dose-dependent manner after lemon juice addition. Accordingly, spinach formulated with 20% of lemon juice appears as the best source of dietary polyphenols with antioxidant and antidiabetic activities and nitrates that may be used as a functional drink.Pozadina istraživanja. Limunov (Citrus limon (L.) Burm) sok bogat je mnogim važnim prirodnim kemijskim spojevima (flavonoidima, limunskom kiselinom i vitaminom C) i njegova je upotreba u tradicionalnoj medicini dobro poznata. Formulacije limunovog soka s voćnim polifenolima u pićima su istražene, ali postoji vrlo malo informacija o njihovoj sposobnosti moduliranja dostupnosti polifenola u probavi. Svrha je ovog istraživanja bila utvrditi stabilnost i dostupnost polifenola špinata (Spinacia oleracea L.) u probavi dodavanjem različitih volumnih udjela soka limuna (0, 2, 5, 10 i 20 %). Eksperimentalni pristup. Sadržaj polifenola i drugih spojeva (nitrata, oksalne kiseline i L-askorbinske kiseline) izmjeren je u formulacijiama špinata s različitim volumnim udjelima limunovog soka u uzorcima prije i nakon in vitro modela ljudske probave. Također su mjerene antioksidacijska sposobnost i svojstvo inhibicije aktivnosti α-amilaze u formulacijama špinata s limunovim sokom. Rezultati i zaključci. Najizraženije povećanje udjela ukupnih polifenola, flavonoida i fenolnih kiselina, te oksalne kiseline i nitrata zabilježeno je prije probave i u gotovo svim probavljenim uzorcima špinata formuliranim s najvećim volumnim udjelom limunovog soka. U istom uzorku udio pojedinih spojeva značajno se povećao nakon faze probave u ustima (L-askorbinska kiselina), inicijalnoj (p-kumarinska kiselina) i intestinalnoj fazi (kvercetin). Visoka biodostupnost polifenola i L-askorbinske kiseline u svim fazama probave primijećena je u gotovo svim formulacijama špinata s limunovim sokom, s izuzetkom nitrata u želučanoj i crijevnoj fazi te oksalne kiseline u crijevnoj fazi, koji su imali umjerenu biodostupnost. Novina i znanstveni doprinos. Po prvi put je ispitana stabilnost i dostupnost u probavi polifenola špinata, oksalne kiseline, nitrata i L-askorbinske kiseline uz dodatak različitih volumnih udjela soka limuna. pH-vrijednost i L-askorbinska kiselina limunovog soka povećavaju stabilnost i dostupnost polifenola u formulaciji špinata s limunovim sokom tijekom in vitro probave. Antioksidacijska i sposobnost inhibicije aktivnosti α-amilaze povećavaju se ovisno o povećanju doze limunovog soka. Sukladno tome, formulacija špinata s 20 % limunovog soka predstavlja najbolji izvor dijetetskih polifenola s antioksidacijskim i antidijabetičkim djelovanjem te nitrata koji se mogu koristiti kao funkcionalni napitak

The Role of Polyphenols in Abiotic Stress Response: The Influence of Molecular Structure

Abiotic stressors such as extreme temperatures, drought, flood, light, salt, and heavy metals alter biological diversity and crop production worldwide. Therefore, it is important to know the mechanisms by which plants cope with stress conditions. Polyphenols, which are the largest group of plant-specialized metabolites, are generally recognized as molecules involved in stress protection in plants. This diverse group of metabolites contains various structures, from simple forms consisting of one aromatic ring to more complex ones consisting of large number of polymerized molecules. Consequently, all these molecules, depending on their structure, may show different roles in plant growth, development, and stress protection. In the present review, we aimed to summarize data on how different polyphenol structures influence their biological activity and their roles in abiotic stress responses. We focused our review on phenolic acids, flavonoids, stilbenoids, and lignans

Correlations between Phytohormones and Drought Tolerance in Selected Brassica Crops: Chinese Cabbage, White Cabbage and Kale

Drought is one of the major abiotic stresses affecting the productivity of Brassica crops. To understand the role of phytohormones in drought tolerance, we subjected Chinese cabbage (B. rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata), and kale (B. oleracea var. acephala) to droughta nd examined the stress response on the physiological, biochemical and hormonal levels. The phytohormones abscisic acid (ABA), auxin indole-3-acetic acid (IAA), brassinosteroids (BRs), cytokinins (CKs), jasmonates (JAs), and salicylic acid (SA) were analyzed by ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS). Based on the physiological and biochemical markers the Chinese cabbage exhibited the lowest tolerance, followed by the white cabbage, while the kale appeared to be the most tolerant to drought. The drought tolerance of the kale correlated with increased levels of SA, ABA, IAA, CKs iP(R) and cZ(R), and typhasterol (TY), a precursor of active BRs. In contrast, the drought sensitivity of the Chinese cabbage correlated with a significant increase in ABA, JAs and the active BRs castasterol (CS) and brassinolide (BL). The moderately tolerant white cabbage, positioned between the kale and Chinese cabbage, showed more similarity in terms of the phytohormone patterns with the kale. We concluded that the drought tolerance in Brassicaceae is mostly determined by the increased endogenous levels of IAA, CKs, ABA and SA and the decreased levels of active BRs

Early Brassica crops responses to salinity stress: a comparative analysis between Chinese cabbage, white cabbage and kale

Soil salinity is severely affecting crop productivity in many countries, particularly in the Mediterranean area. To evaluate early plant responses to increased salinity and characterize tolerance markers, three important Brassica crops - Chinese cabbage (Brassica rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata) and kale (B. oleracea var. acephala) were subjected to short-term (24 h) salt stress by exposing them to NaCl at concentrations of 50, 100 or 200 mM. Physiological (root growth, photosynthetic performance parameters, and Na+/K+ ratio) and biochemical parameters (proline content, and lipid peroxidation as indicated by malondialdehyde, MDA, levels) in the plants' roots and leaves were then measured. Photosynthetic parameters such as the total performance index PItotal (describing the overall efficiency of PSI, PSII and the intersystem electron transport chain) appeared to be the most salinity-sensitive parameter and informative stress marker. This parameter was decreased more strongly in Chinese cabbage than in white cabbage and kale. It indicated that salinity reduced the capacity of the photosynthetic system for efficient energy conversion, particularly in Chinese cabbage. In parallel with the photosynthetic impairments, the Na+/K+ ratio was highest in Chinese cabbage leaves and lowest in kale leaves while kale root is able to keep high Na+/K+ ratio without a significant increase in MDA. Thus Na+/ K+ ratio, high in root and low in leaves accompanying with low MDA level is an informative marker of salinity tolerance. The crops' tolerance was positively correlated with levels of the stress hormone abscisic acid (ABA) and negatively correlated with levels of jasmonic acid (JA) and jasmonoyl-L-isoleucine (JA-Ile). Furthermore, salinity induced contrasting changes in levels of the growth-promoting hormones brassinosteroids (BRs). The crop’s tolerance was positively correlated with levels of BR precursor typhasterol while negatively with the active BR brassinolide. Principal Component Analysis revealed correlations in observed changes in phytohormones, biochemical and physiological parameters. Overall, the results show that kale is the most tolerant of the three species and Chinese cabbage the most sensitive to salt stress, and provide holistic indications of the spectrum of tolerance mechanisms involved

Recycling Electric Arc Furnace Slag into Fertilizer: Effects of “Waste Product” on Growth and Physiology of the Common Bean (<i>Phaseolus vulgaris</i> L.)

The aim of this study was to investigate if electric arc furnace (EAF) slag generated during steel production could have an application as a soil enhancer in agriculture. For that purpose, a greenhouse experiment was conducted on common beans (Phaseolus vulgaris) cultivated in soil enriched with EAF slag (at 1% and 2% level), synthetic fertilizer (NPK), combined EAF slag and synthetic fertilizer, or in control (untreated) soil. The beans were exposed to test soils until maturity (for 8 weeks). Following that period, physico-chemical properties of the soils, as well as nutrient status, growth, photosynthetic and oxidative stress parameters of bean plants were determined. EAF slag improved the mineral status of the soil and significantly increased Fe, Mg, N, P and K in different bean plant organs. EAF slag and/or NPK increased plant height. EAF slag, especially at lower levels, positively affected dry weight of leaf and seed. Soil supplementation with a lower level of EAF slag, as well as with a combination of EAF slag and NPK, led to significant improvement in gas exchange parameters (net photosynthetic rate, intercellular CO2 concentration and stomatal conductance) and nitrate reductase activity, indicating a positive influence on bean plants. Potential phytotoxicity of EAF slag was not detected, as evidenced by the oxidative stress parameters. Thus, EAF slag applied at a low level shows promising potential as an efficient soil enhancer, and as a valuable source of nutrients essential to plants, with an equal or even better performance compared to synthetic fertilizer

Recycling Electric Arc Furnace Slag into Fertilizer: Effects of &ldquo;Waste Product&rdquo; on Growth and Physiology of the Common Bean (Phaseolus vulgaris L.)

The aim of this study was to investigate if electric arc furnace (EAF) slag generated during steel production could have an application as a soil enhancer in agriculture. For that purpose, a greenhouse experiment was conducted on common beans (Phaseolus vulgaris) cultivated in soil enriched with EAF slag (at 1% and 2% level), synthetic fertilizer (NPK), combined EAF slag and synthetic fertilizer, or in control (untreated) soil. The beans were exposed to test soils until maturity (for 8 weeks). Following that period, physico-chemical properties of the soils, as well as nutrient status, growth, photosynthetic and oxidative stress parameters of bean plants were determined. EAF slag improved the mineral status of the soil and significantly increased Fe, Mg, N, P and K in different bean plant organs. EAF slag and/or NPK increased plant height. EAF slag, especially at lower levels, positively affected dry weight of leaf and seed. Soil supplementation with a lower level of EAF slag, as well as with a combination of EAF slag and NPK, led to significant improvement in gas exchange parameters (net photosynthetic rate, intercellular CO2 concentration and stomatal conductance) and nitrate reductase activity, indicating a positive influence on bean plants. Potential phytotoxicity of EAF slag was not detected, as evidenced by the oxidative stress parameters. Thus, EAF slag applied at a low level shows promising potential as an efficient soil enhancer, and as a valuable source of nutrients essential to plants, with an equal or even better performance compared to synthetic fertilizer