Browsing by Person "Klaiber, Iris"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Publication
    Characterization of epidermal bladder cells in Chenopodium quinoa
    (2021) Otterbach, Sophie L.; Khoury, Holly; Rupasinghe, Thusitha; Mendis, Himasha; Kwan, Kim H.; Lui, Veronica; Natera, Siria H. A.; Klaiber, Iris; Allen, Nathaniel M.; Jarvis, David E.; Tester, Mark; Roessner, Ute; Schmöckel, Sandra M.
    Chenopodium quinoa (quinoa) is considered a superfood with its favourable nutrient composition and being gluten free. Quinoa has high tolerance to abiotic stresses, such as salinity, water deficit (drought) and cold. The tolerance mechanisms are yet to be elucidated. Quinoa has epidermal bladder cells (EBCs) that densely cover the shoot surface, particularly the younger parts of the plant. Here, we report on the EBC's primary and secondary metabolomes, as well as the lipidome in control conditions and in response to abiotic stresses. EBCs were isolated from plants after cold, heat, high‐light, water deficit and salt treatments. We used untargeted gas chromatography–mass spectrometry (GC–MS) to analyse metabolites and untargeted and targeted liquid chromatography‐MS (LC–MS) for lipids and secondary metabolite analyses. We identified 64 primary metabolites, including sugars, organic acids and amino acids, 19 secondary metabolites, including phenolic compounds, betanin and saponins and 240 lipids categorized in five groups including glycerolipids and phospholipids. We found only few changes in the metabolic composition of EBCs in response to abiotic stresses; these were metabolites related with heat, cold and high‐light treatments but not salt stress. Na+ concentrations were low in EBCs with all treatments and approximately two orders of magnitude lower than K+ concentrations.
  • Thumbnail Image
    Publication
    Chemometric approach for profiling of metabolites of potential antioxidant activity in Apiaceae species based on LC-PDA-ESI-MS/MS and FT-NIR
    (2023) Atta, Noha H.; Handoussa, Heba; Klaiber, Iris; Hitzmann, Bernd; Hanafi, Rasha S.
    Chemometrics is a tool for data mining and unlocking the door for solving big data queries. Apiaceae is a family species which is commonly cultivated worldwide. Although members of this species are widely used as antioxidant, antibacterial, antifungal, and anti-inflammatory agents, their metabolites profiling remains ambiguous. Based on WHO support, chemometrics has been used in evaluating the quality and authenticity of the herbal products. The objective of this study is to profile and characterize phenolic metabolites in nine species from Egyptian cultivars and three different species of German cultivars from the Apiaceae family using multivariate analysis after LC-PDA-ESI-MS/MS and near infrared spectroscopy data are generated. Principal component analysis was successfully applied to distinguish between the nine Egyptian cultivars and the three German cultivars, and hierarchical cluster analysis also confirmed this distinctive clustering. Partial least square regression (PLS-R) models showed a relationship between phytochemicals and antioxidant activities. The metabolites responsible for the clustering pattern and variables important for projection (VIP) were identified, being twelve amongst nine Egyptian cultivar samples and thirteen amongst the Egyptian cultivar and the German cultivar comparison. The identified VIPs were also correlated with the antioxidant activity using PLS-R. In conclusion, the study showed novelty in the application of hyphenated analytical techniques and chemometrics that assist in quality control of herbal medicine.
  • Thumbnail Image
    Publication
    Comparison of aqueous and lactobacterial-fermented Mercurialis perennis L. (Dog’s Mercury) extracts with respect to their immunostimulating activity
    (2023) Lorenz, Peter; Zilkowski, Ilona; Mailänder, Lilo K.; Klaiber, Iris; Nicolay, Sven; Garcia-Käufer, Manuel; Zimmermann-Klemd, Amy M.; Turek, Claudia; Stintzing, Florian C.; Kammerer, Dietmar R.; Gründemann, Carsten
    Lactic acid (LA) fermentation of dog’s mercury (M. perennis L.) herbal parts was investigated in samples inoculated with either Lactobacteria (Lactobacillus plantarum and Pediococcus pentosaceus, LBF) or whey (WF). Depending on fermentation time, LA concentrations were monitored in a range of 3.4–15.6 g/L with a concomitant pH decline from 6.5 to 3.9. A broad spectrum of cinnamic acids depsides containing glucaric, malic and 2-hydroxyglutaric acids along with quercetin and kaempferol glycosides were detected by LC-DAD-ESI-MSn. Moreover, in this study novel constituents were also found both in unfermented and fermented extracts. Furthermore, amino acids and particular Lactobacteria metabolites such as biogenic amines (e.g., putrescine, 4-aminobutyric acid, cadaverine) and 5-oxoproline were assigned in WF extracts by GC-MS analysis after silylation. Enhanced NFκB and cytokine expression (IL-6, TNFα, IL-8 and IL-1β) was induced by all extracts, both non-fermented and fermented, in NFκB-THP-1 reporter cells, showing a concentration-dependent immunostimulatory effect. The WF extracts were tested for micronuclei formation in THP-1 cells and toxicity in luminescent bacteria (V. fischeri), whereby no mutagenic or toxic effects could be detected, which corroborates their safe use in pharmaceutical remedies.
  • Thumbnail Image
    Publication
    Orotic acid production by Yarrowia lipolytica under conditions of limited pyrimidine
    (2021) Swietalski, Paul; Hetzel, Frank; Klaiber, Iris; Pross, Eva; Seitl, Ines; Fischer, Lutz
    Orotic acid (OA) is an intermediate of the pyrimidine biosynthesis with high industrial relevance due to its use as precursor for production of biochemical pyrimidines or its use as carrier molecule in drug formulations. It can be produced by fermentation of microorganisms with engineered pyrimidine metabolism. In this study, we surprisingly discovered the yeast Yarrowia lipolytica as a powerful producer of OA. The overproduction of OA in the Y. lipolytica strain PO1f was found to be caused by the deletion of the URA3 gene which prevents the irreversible decarboxylation of OA to uridine monophosphate. It was shown that the lack of orotidine‐5′‐phosphate decarboxylase was the reason for the accumulation of OA inside the cell since a rescue mutant of the URA3 deletion in Y. lipolytica PO1f completely prevented the OA secretion into the medium. In addition, pyrimidine limitation in the cell massively enhanced the OA accumulation followed by secretion due to intense overflow metabolism during bioreactor cultivations. Accordingly, supplementation of the medium with 200 mg/L uracil drastically decreased the OA overproduction by 91%. OA productivity was further enhanced in fed‐batch cultivation with glucose and ammonium sulfate feed to a maximal yield of 9.62 ± 0.21 g/L. Y. lipolytica is one of three OA overproducing yeasts described in the literature so far, and in this study, the highest productivity was shown. This work demonstrates the potential of Y. lipolytica as a possible production organism for OA and provides a basis for further metabolic pathway engineering to optimize OA productivity.