Phytotoxicity of Bisphenol A to Allium cepa Root Cells Is Mediated through Growth Hormone Gibberellic Acid and Reactive Oxygen Species.

The aim of this study was to test the phytotoxicity and mode of action of bisphenol A (BPA) on Allium cepa using a multibiomarker approach. A. cepa roots were exposed to BPA in concentration range 0-50 mg L-1 for 3 days. BPA even in the lowest applied concentration (1 mg L-1) reduced root length, root fresh weight, and mitotic index. Additionally, the lowest BPA concentration (1 mg L-1) decreased the level of gibberellic acid (GA3) in root cells. BPA at concentration 5 mg L-1 increased production of reactive oxygen species (ROS) that was followed by increase in oxidative damage to cells' lipids and proteins and activity of enzyme superoxide dismutase. BPA in higher concentrations (25 and 50 mg L-1) induced genome damage detected as an increase in micronucleus (MNs) and nuclear buds (NBUDs). BPA at >25 mg L-1 induced synthesis of phytochemicals. Results of this study using multibiomarker approach indicate that BPA is phytotoxic to A. cepa roots and has shown genotoxic potential to plants, thus its presence in the environment should be monitored.

Lemon Juice Formulations Modulate In Vitro Digestive Recovery of Spinach Phytochemicals.

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.

Proteome changes in human bladder T24 cells induced by hydroquinone derived from Arctostaphylos uva-ursi herbal preparation.

ETHNOPHARMACOLOGICAL RELEVANCE: Arctostaphylos uva-ursi (L.) Spreng. (bearberry) is a well-known traditional herbal plant used as a urinary tract disinfectant. Its antiseptic and diuretic properties can be attributed to hydroquinone, obtained by hydrolysis of arbutin. AIM OF THE STUDY: This study aimed to determine the toxic profile of free hydroquinone on urinary bladder cells (T24) as a target of therapeutic action. MATERIALS AND METHODS: Quantitative and qualitative analysis of the extract and the digestive stability and bioavailability of arbutin and hydroquinone were performed by HPLC assay and simulated in vitro digestion, respectively. Cytotoxic effect, reactive oxygen species induction and proteome changes in T24 cells after hydroquinone treatment were determined using Neutral red assay, 2',7'-dichlorofluorescein-diacetate (DCFH-DA) assay and mass spectrometry, respectively. RESULTS: Through in vitro digestion, arbutin was stable, but hydroquinone increased after pepsin treatment (109.6%) and then decreased after the small intestine phase (65.38%). The recommended doses of Uva-ursi had a cytotoxic effect on T24 cells only when all hydroquinone conjugates were converted to free hydroquinone (320 and 900 µg/mL) and the toxic effect was enhanced by recovery. One cup of the therapeutic dose had a prooxidative effect after 4 h of incubation. Shorter time of cell exposure (2 h) to hydroquinone did not have any impact on reactive oxygen species induction. Proteomic analysis found 17 significantly up-regulated proteins compared to control. Hydroquinone activated proteins related to oxidative stress response, stress-adaptive signalling, heat shock response and initiation of translation. CONCLUSIONS: Despite the therapeutic properties of bearberry, up-regulated T24 cell proteins are evidence that plant compounds, although from a natural source, may exhibit negative properties.

Matcha and Sencha green tea extracts with regard to their phenolics pattern and antioxidant and antidiabetic activity during in vitro digestion.

The purpose of this study was to compare the polyphenol, antioxidant and antidiabetic potential of powdered Matcha and bagged Sencha tea during in vitro digestion. Total phenols (TP), flavonoids (TF), flavanols (TFLA), antioxidant and antidiabetic (α-glucosidase inhibition) activity were higher in Matcha tea before and in most in vitro digestion phases. Upon gastric digestion, in Matcha tea TP, TF, TFLA were 2.6, 1.4 and 1.2 times significantly higher (p ≤ 0.05), respectively; gallic acid, gallocatechin, epigallocatechin, quercetin and kaempferol 1.5, 1.6, 1.8, 1.7, 1.2 times, respectively; whereas antioxidant activity was significantly (p ≤ 0.05) higher 3.2 and 1.1 times with ABTS and FRAP and α-glucosidase inhibition 1.8 times. After the intestinal phase, TP and TFLA were 3.4 and 1.7 times significantly (p ≤ 0.05) higher, respectively, antioxidant activity was significantly (p ≤ 0.05) higher 2.4 and 2.0 times with ABTS and FRAP, respectively, while inhibition of α-glucosidase was 1.7 time significantly (p ≤ 0.05) higher in Matcha tea, but the differences in TF, TP and identified phenolics (with the exception of gallic acid) between Matcha and Sencha tea were neutralized. Our results are the first to demonstrate that, during digestion of Matcha powder together with its water extract, Matcha polyphenols are more bioavailable and possess higher antioxidant and antidiabetic activity compared to Sencha. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13197-021-05086-5.

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.

Improving the phytochemical profile and bioactivity of Chinese cabbage sprouts by interspecific transfer of metabolites.

The high demand for healthy food in recent years has led to an increasing need for highly bioactive plant materials. One such plant, Chinese cabbage, possesses flavonoids with antioxidant and antidiabetic properties, but they appear in low quantities. The interspecific transfer of metabolites is a promising technique that could contribute to the increase of the beneficial properties of food. The objective of the study was to determine how an interspecific source-sink phytochemical transfer from donor extracts to the Chinese cabbage affects its phenolic and vitamin C profile and intestinal bioaccessibility, hypoglycemic potential and antioxidant capacity. In addition, sprouts treated with Rosa sp. and Hypericum perforatum extracts showed better antiproliferative effect towards human breast adenocarcinoma cells than untreated sprouts. The results suggest that treatment of plants with donor extracts is a promising approach to improve the nutritional and phytochemical profile and bioactive properties of acceptor plants.

Developmentally-related changes in phenolic and L-ascorbic acid content and antioxidant capacity of Chinese cabbage sprouts.

The phytochemical and antioxidant properties of mature (head stage) Chinese cabbage (Brassica rapa ssp. pekinensis) are known; however, data on the phenolic profile, vitamin C (L-ascorbic acid) content and antioxidant capacity of its fresh sprouts are lacking. Since the human consumption of fresh cruciferous sprouts has significantly increased in recent years, their nutritional characterization has become a somewhat urgent matter. Therefore, in this study the contents of total phenolics, flavonols and hydroxycinnamic acids were measured spectrophotometrically, whereas individual flavonoids, phenolic acids and vitamin C were identified and quantified using a newly-developed high performance liquid chromatography method. Also, the antioxidant capacity of five Chinese cabbage sprout growth stages was determined. These stages contained either cotyledons only (seedlings), cotyledons and two leaves, four leaves, six leaves, or ten leaves. Principal component analysis (PCA) and hierarchical clustering (HC) were implemented in order to visualize the classification trend between the stages. Seedlings contained more sinapic acid and vitamin C than older plants. Plants containing six or ten leaves had more ferulic acid and isorhamnetin than younger ones. Total phenolics, flavonols, hydroxycinnamic acids, quercetin and antioxidant capacity did not statistically differ between seedlings and stages with six or ten leaves and their concentrations were significantly higher than in stages with two or four leaves. PCA and HC confirmed the higher phytochemical similarity between seedlings and plants with six or ten leaves than plants with two or four leaves. Therefore, Chinese cabbage seedlings and plants with six or ten leaves should be preferred over plants with two or four leaves, which were ultimately shown to be of lesser nutritional quality.

Involvement of Phenolic Acids in Short-Term Adaptation to Salinity Stress is Species-Specific among Brassicaceae.

Salinity is a major abiotic stress negatively affecting plant growth and consequently crop production. The effects of short-term salt stress were evaluated on seedlings of three globally important Brassica crops-Chinese cabbage (Brassica rapa ssp. pekinensis), white cabbage (Brassica oleracea var. capitata), and kale (Brassica oleracea var. acephala)-with particular focus on phenolic acids. The physiological and biochemical stress parameters in the seedlings and the levels of three main groups of metabolites (total glucosinolates, carotenoids, and phenolics) and individual phenolic acids were determined. The salt treatments caused a dose-dependent reduction in root growth and biomass and an increase in stress parameters (Na+/K+ ratio, reactive oxygen species (ROS) and glutathione (GSH)) in all seedlings but most prominently in Chinese cabbage. Based on PCA, specific metabolites grouped close to the more tolerant species, white cabbage and kale. The highest levels of phenolic acids, particularly hydroxycinnamic acids, were determined in the more tolerant kale and white cabbage. A reduction in caffeic, salicylic, and 4-coumaric acid was found in Chinese cabbage and kale, and an increase in ferulic acid levels was found in kale upon salinity treatments. Phenolic acids are species-specific among Brassicaceae, and some may participate in stress tolerance. Salt-tolerant varieties have higher levels of some phenolic acids and suffer less from metabolic stress disorders under salinity stress.

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 drought and 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.