570 Biowissenschaften; Biologie
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- 1-Methoxy-3-indolylmethyl glucosinolate (1)
- 7 macrophages (1)
- Aflatoxin B1 (1)
- African indigenous vegetables (1)
- Amaranth (1)
- Amaranthaceae (1)
- Aspergillus (1)
- Blood protein adducts (1)
- Brassica (1)
- Brassica rapa ssp. chinensis (1)
We previously showed that purified 1-methoxy-3-indolylmethyl (1-MIM) glucosinolate, a secondary plant metabolite in Brassica species, is mutagenic in various in vitro systems and forms DNA and protein adducts in mouse models. In the present study, we administered 1-MIM glucosinolate in a natural matrix to mice, by feeding a diet containing pak choi powder and extract. Groups of animals were killed after 1, 2, 4 and 8 days of pak choi diet, directly or, in the case of the 8-day treatment, after 0, 8 and 16 days of recovery with pak choi-free diet. DNA adducts [N-2-(1-MIM)-dG, N-6-(1-MIM)-dA] in six tissues, as well as protein adducts [tau N-(1-MIM)-His] in serum albumin (SA) and hemoglobin (Hb) were determined using UPLC-MS/MS with isotopically labeled internal standards. None of the samples from the 12 control animals under standard diet contained any 1-MIM adducts. All groups receiving pak choi diet showed DNA adducts in all six tissues (exception: lung of mice treated for a single day) as well as SA and Hb adducts. During the feeding period, all adduct levels continuously increased until day 8 (in the jejunum until day 4). During the 14-day recovery period, N-2-(1-MIM)-dG in liver, kidney, lung, jejunum, cecum and colon decreased to 52, 41, 59, 11, 7 and 2%, respectively, of the peak level. The time course of N-6-(1-MIM)-dA was similar. Immunohistochemical analyses indicated that cell turnover is a major mechanism of DNA adduct elimination in the intestine. In the same recovery period, protein adducts decreased more rapidly in SA than in Hb, to 0.7 and 37%, respectively, of the peak level, consistent with the differential turnover of these proteins. In conclusion, the pak choi diet lead to the formation of high levels of adducts in mice. Cell and protein turnover was a major mechanism of adduct elimination, at least in gut and blood.
For centuries, Amaranthus sp. were used as food, ornamentals, and medication. Molecular mechanisms, explaining the health beneficial properties of amaranth, are not yet understood, but have been attributed to secondary metabolites, such as phenolic compounds. One of the most abundant phenolic compounds in amaranth leaves is 2-caffeoylisocitric acid (C-IA) and regarding food occurrence, C-IA is exclusively found in various amaranth species. In the present study, the anti-inflammatory activity of C-IA, chlorogenic acid, and caffeic acid in LPS-challenged macrophages (RAW 264.7) has been investigated and cellular contents of the caffeic acid derivatives (CADs) were quantified in the cells and media. The CADs were quantified in the cell lysates in nanomolar concentrations, indicating a cellular uptake. Treatment of LPS-challenged RAW 264.7 cells with 10 µM of CADs counteracted the LPS effects and led to significantly lower mRNA and protein levels of inducible nitric oxide synthase, tumor necrosis factor alpha, and interleukin 6, by directly decreasing the translocation of the nuclear factor κB/Rel-like containing protein 65 into the nucleus. This work provides new insights into the molecular mechanisms that attribute to amaranth’s anti-inflammatory properties and highlights C-IA’s potential as a health-beneficial compound for future research.
Consumption of Brassica vegetables is linked to health benefits, as they contain high concentrations of the following secondary plant metabolites (SPMs): glucosinolate breakdown products, carotenoids, chlorophylls, and phenolic compounds. Especially Brassica vegetables are consumed as microgreens (developed cotyledons). It was investigated how different ontogenetic stages (microgreens or leaves) of pak choi (Brassica rapa subsp. chinensis) and kale (Brassica oleracea var. sabellica) differ in their SPM concentration. The impact of breadmaking on SPMs in microgreens (7 days) and leaves (14 days) in pak choi and kale as a supplement in mixed wheat bread was assessed. In leaves, carotenoids, chlorophylls, and phenolic compounds were higher compared to those of microgreens. Breadmaking caused a decrease of SPMs. Chlorophyll degradation was observed, leading to pheophytin and pyropheophytin formation. In kale, sinapoylgentiobiose, a hydroxycinnamic acid derivative, concentration increased. Thus, leaves of Brassica species are suitable as natural ingredients for enhancing bioactive SPM concentrations in bread.
Amaranth is presently an underutilized crop despite its high content of micronutrients/bioactive phytochemicals and its capacity to thrive in harsh environmental condition. The present study aimed at determining the health benefits of Amaranthus cruentus L. in terms of protection against DNA damage induced by the mycotoxin aflatoxin B1 (AFB1) and oxidative stress using comet assay. The antioxidant potential was further investigated using electron paramagnetic resonance spectroscopy (EPR) and an ARE/Nrf2 reporter gene assay in vitro in a human liver model using the HepG2 cell line. Ethanolic extracts from fresh leaves grown under controlled conditions were used and additionally analyzed for their phytochemical content using liquid chromatography-mass spectrometry (LC-MS). The extracts inhibited both AFB1- and oxidative stress-induced DNA damage in a concentration dependent way with a maximum effect of 57% and 81%, respectively. Oxidative stress triggered using ferrous sulfate was blocked by up to 38% (EPR); the potential to induce antioxidant enzymes using ARE/Nrf2-mediated gene expression was also confirmed. Based on these in vitro findings, further studies on the health-protecting effects of A. cruentus are encouraged to fully explore its health promoting potential and provide the scientific basis for encouraging its cultivation and consumption.
Light quality-induced changes of carotenoid composition in pak choi Brassica rapa ssp. chinensis
(2019)
Carotenoids as part of the photosystems are crucial for their assembly, light-harvesting, and photoprotection. Light of different wavelengths impacts the composition and structure of photosystems, thus offering the possibility to influence the carotenoid concentrations and composition in photosystems by illumination with specific narrow-banded light spectra. Key components involved in the regulation of gene transcription are still poorly characterized, particularly in leafy vegetables as compared to model plants. In particular, the effect of different light qualities and its connection to redox control mechanisms, which also determine the photosystem composition and structure, is not yet well understood. Furthermore, light quality effects are species-dependent, and thus, increase the need to perform research on individual vegetable species such as pak choi Brassica rapa ssp. chinensis. Here, we investigated the carotenoid concentrations and composition of pak choi sprouts grown for 6 days under blue, red, or white light emitting diodes (LEDs) as light source. After 6 days, the total carotenoid content was the highest under white and slightly reduced under blue or red LEDs. Blue, red, and white light differently affected the carotenoid composition mainly due to variations of the beta-carotene content which could be correlated to changes in the transcript levels of beta-carotene hydroxylase 1 (beta-OHASE1). Further investigations implied a redox controlled gene expression of beta-OHASE1. In addition, transcription factors related to light signaling and the circadian clock differed in their transcriptional abundance after exposure to blue and red light. RNA-Seq analysis also revealed increased transcript levels of genes encoding the outer antenna complex of photosystem II under red compared to blue light, indicating an adjustment of the photosystems to the different light qualities which possibly contributed to the alternations in the carotenoid content and composition.
The spider mite Tetranychus urticae Koch and the aphid Myzus persicae (Sulzer) both infest a number of economically significant crops, including tomato (Solanurn lycopersicum). Although used for decades to control pests, the impact of green lacewing larvae Chrysoperla carnea (Stephens) on plant biochemistry was not investigated. Here, we used profiling methods and targeted analyses to explore the impact of the predator and herbivore(s)-predator interactions on tomato biochemistry. Each pest and pest -predator combination induced a characteristic metabolite signature in the leaf and the fruit thus, the plant exhibited a systemic response. The treatments had a stronger impact on non-volatile metabolites including abscisic acid and amino acids in the leaves in comparison with the fruits. In contrast, the various biotic factors had a greater impact on the carotenoids in the fruits. We identified volatiles such as myrcene and alpha-terpinene which were induced by pest -predator interactions but not by single species, and we demonstrated the involvement of the phytohormone abscisic acid in tritrophic interactions for the first time. More importantly, C. carnea larvae alone impacted the plant metabolome, but the predator did not appear to elicit particular defense pathways on its own. Since the presence of both C. carnea larvae and pest individuals elicited volatiles which were shown to contribute to plant defense, C. carnea larvae could therefore contribute to the reduction of pest infestation, not only by its preying activity, but also by priming responses to generalist herbivores such as T urticae and M. persicae. On the other hand, the use of C. carnea larvae alone did not impact carotenoids thus, was not prejudicial to the fruit quality. The present piece of research highlights the specific impact of predator and tritrophic interactions with green lacewing larvae, spider mites, and aphids on different components of the tomato primary and secondary metabolism for the first time, and provides cues for further in-depth studies aiming to integrate entomological approaches and plant biochemistry.
Tea aroma is one of the most important factors affecting the character and quality of tea. Here we describe the practical application of methyl jasmonate (MeJA) to improve the aroma quality of teas. The changes of selected metabolites during crucial tea processing steps, namely, withering, fixing and rolling, and fermentation, were analyzed. MeJA treatment of tea leaves (12, 24, 48, and 168 h) greatly promotes the aroma quality of green, oolong, and black tea products when comparing with untreated ones (0 h) and as confirmed by sensory evaluation. MeJA modulates the aroma profiles before, during, and after processing. Benzyl alcohol, benzaldehyde, 2-phenylethyl alcohol, phenylacetaldehyde, and trans-2-hexenal increased 1.07- to 3-fold in MeJA-treated fresh leaves and the first two maintained at a higher level in black tea and the last two in green tea. This correlates with a decrease in aromatic amino acids by more than twofold indicating a direct relation to tryptophan- and phenylalanine-derived volatiles. MeJA-treated oolong tea was characterized by a more pleasant aroma. Especially the terpenoids linalool and oxides, geraniol, and carvenol increased by more than twofold.
Continuing advances in 'omics methodologies and instrumentation is enhancing the understanding of how plants cope with the dynamic nature of their growing environment. 'Omics platforms have been only recently extended to cover horticultural crop species. Many of the most widely cultivated vegetable crops belong to the genus Brassica: these include plants grown for their root (turnip, rutabaga/swede), their swollen stem base (kohlrabi), their leaves (cabbage, kale, pak choi) and their inflorescence (cauliflower, broccoli). Characterization at the genome, transcript, protein and metabolite levels has illustrated the complexity of the cellular response to a whole series of environmental stresses, including nutrient deficiency, pathogen attack, heavy metal toxicity, cold acclimation, and excessive and sub optimal irradiation. This review covers recent applications of omics technologies to the brassicaceous vegetables, and discusses future scenarios in achieving improvements in crop end-use quality.