Institut für Ernährungswissenschaften

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The antiviral activity of polyphenols
(2025) Burkard, Markus; Piotrowsky, Alban; Leischner, Christian; Detert, Katja; Venturelli, Sascha; Marongiu, Luigi; Burkard, Markus; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany; Piotrowsky, Alban; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany; Leischner, Christian; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany; Detert, Katja; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany; Venturelli, Sascha; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany; Marongiu, Luigi; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany
Polyphenols are secondary metabolites produced by a large variety of plants. These compounds that comprise the class of phenolic acids, stilbenes, lignans, coumarins, flavonoids, and tannins have a wide range of employment, from food production to medical usages. Among the beneficial applications of polyphenols, their antiviral activity is gaining importance due to the increased prevalence of drug‐resistant viruses such as herpes and hepatitis B viruses. In the present review, we provide an overview of the most promising or commonly used antiviral polyphenols and their mechanisms of action focusing on their effects on enveloped viruses of clinical importance (double‐stranded linear or partially double‐stranded circular DNA viruses, negative sense single‐stranded RNA viruses with nonsegmented or segmented genomes, and positive sense single‐stranded RNA viruses). The present work emphasizes the relevance of polyphenols, in particular epigallocatechin‐3‐gallate and resveratrol, as alternative or supportive antivirals. Polyphenols could interfere with virtually all steps of viral infection, from the adsorption to the release of viral particles. The activity of polyphenols against viruses is especially relevant given the risk of widespread outbreaks associated with viruses, remarked by the recent COVID‐19 pandemic.
Bioaccessibility and anti-inflammatory activity in Caco-2 cells of phytochemicals from industrial by-products of coffee (Coffea arabica L.)
(2025) Jiménez-Gutiérrez, Milena; Zielinski, Christian; Esquivel, Patricia; Frank, Jan; Irías-Mata, Andrea; Jiménez-Aspee, Felipe
Coffee by-products are rich in nutrients and bioactive compounds in free soluble form and bound to cell wall components. These compounds undergo chemical changes during gastrointestinal digestion, affecting their bioaccessibility and bioactivity. This study is the first to investigate coffee by-products from industrial wet processing to evaluate the impact of simulated gastrointestinal digestion on their phytochemical composition and subsequent anti-inflammatory activity in Caco-2 cells. Digestion significantly reduced the stability and solubility of main compounds; however, digested bioaccessible by-products still exhibited anti-inflammatory properties, reducing IL-6, IL-8, and TNF-α levels. Correlation analysis identified rutin, quercetin-3-glycoside, caffeine and 5-caffeoylquinic acid as strongly linked to cytokine suppression, suggesting key roles and possible synergies. These results highlight the potential of coffee by-products as functional ingredients targeting intestinal inflammation. Future work should confirm in vivo efficacy, optimize extraction at scale, and address regulatory requirements to support industrial application and promote circular economy benefits.
Monodopsis subterranea is a source of α‐tocomonoenol, and its concentration, in contrast to α‐tocopherol, is not affected by nitrogen depletion
(2024) Montoya‐Arroyo, Alexander; Muñoz‐González, Alejandra; Lehnert, Katja; Frick, Konstantin; Schmid‐Staiger, Ulrike; Vetter, Walter; Frank, Jan
α-Tomonoenols (αT1) are tocochromanols structurally related to tocopherols (T) and tocotrienols (T3), the bioactive members of the vitamin E family. However, limited evidence exists regarding the sources and biosynthesis of tocomonoenols. Nitrogen depletion increases the content of α-tocopherol (αT), the main vitamin E congener, in microalgae, but little is known regarding its effect on other tocochromanols, such as tocomonoenols and tocotrienols. We therefore quantified the concentrations of T, T1, and T3, in freeze-dried biomass from nitrogen-sufficient, and nitrogen-depleted Monodopsis subterranea (Eustigmatophyceae). The identities of isomers of αT1 were confirmed by LC–MS and GC–MS. αT was the predominant tocochromanol (82% of total tocochromanols). αT1 was present in higher quantities than the sum of all T3 (6% vs. 1% of total tocochromanols). 11′-αT1 was the main αT1 isomer. Nitrogen depletion increased αT, but not αT1 or T3 in M. subterranea. In conclusion, nitrogen depletion increased the content of αT, the biologically most active form of vitamin E, in M. subterranea without affecting αT1 and T3 and could potentially be used as a strategy to enhance its nutritional value but not to increase αT1 content, indicating that αT1 accumulation is independent of that of αT in microalgae.
The non-nutritive sweetener rebaudioside a enhances phage infectivity
(2025) Marongiu, Luigi; Brzozowska, Ewa; Brykała, Jan; Burkard, Markus; Schmidt, Herbert; Szermer-Olearnik, Bożena; Venturelli, Sascha
Non-nutritive sweeteners (NNS) are widely employed in foodstuffs. However, it has become increasingly evident that their consumption is associated with bacterial dysbiosis, which, in turn, is linked to several health conditions, including a higher risk of type 2 diabetes and cancer. Among the NNS, stevia, whose main component is rebaudioside A (rebA), is gaining popularity in the organic food market segment. While the effect of NNS on bacteria has been established, the impact of these sweeteners on bacterial viruses (phages) has been neglected, even though phages are crucial elements in maintaining microbial eubiosis. The present study sought to provide a proof-of-concept of the impact of NNS on phage infectivity by assessing the binding of rebA to phage proteins involved in the infection process of enteropathogenic bacteria, namely the fiber protein gp17 of Yersinia enterocolitica phage φYeO3-12 and the tubular baseplate protein gp31 of Klebsiella pneumoniae phage 32. We employed docking analysis and a panel of in vitro confirmatory tests (microscale thermophoresis, RedStarch ™ depolymerization, adsorption, and lysis rates). Docking analysis indicated that NNS can bind to both fiber and baseplate proteins. Confirmatory assays demonstrated that rebA can bind gp31 and that such binding increased the protein’s enzymatic activity. Moreover, the binding of rebA to gp17 resulted in a decrease in the adsorption rate of the recombinant protein to its host but increased the Yersinia bacteriolysis caused by the whole phage compared to unexposed controls. These results support the hypothesis that NNS can impair phage infectivity, albeit the resulting effect on the microbiome remains to be elucidated.
Nutritional potential of underutilized edible plant species in coffee agroforestry systems of Yayu, southwestern Ethiopia
(2021) Aragaw, Habtamu Seyoum; Nohr, Donatus; Callo-Concha, Daniel
Ethiopia is confronted with the paradox of hosting hundreds of edible plants and having high food and nutritional insecurity. Meals are mainly made up of staples and often lack of protein and micronutrients. Therefore, a large section of the population, particularly children and women, are malnourished. We hypothesize that wild edible plant species can contribute to fulfil the micronutrient demands of local people. Hence, we assessed the nutritional potential of underutilized edible plant species growing in understories of coffee agroforestry systems of southwestern Ethiopia. An ethnobotanical household survey (n = 300) documented the edible existing plants; and a promising subset of them (n = 12) was analysed for nutrient and antinutritional factor content in the lab. All 12 species, except fruits, have higher calcium, iron and zinc contents compared to regularly cultivated crops. Vitamin C was high in Syzygium guineense (330.72 mg/100 g edible parts or EP) and Rubus apetalus (294.19 mg/100 g). Beta-carotene ranged from 9.2 to 75 µg retinol activity equivalent (RAE) /100 g 25 among all species, but was exceptionally high in Rubus apetalus (161.7 µg RAE/100 g). Concerning the antinutritional factors, phytate content varied from 31.06 to 601.65 µg/100 g, being lower in Dioscorea prehensilis (31.06 µg/100 g) and D. alata (90.17 µg/100 g) compared to Carissa spinarum (601.65 µg/100 g) and Solanum nigrum (536.48 µg/100 g). Thus, we conclude that the assessed underutilized species are potential sources of dietary nutrients locally needed, and are notable Amaranthus graecizans, Portulaca oleracea and Dioscorea cayenensis as providers of Ca, Fe and Zn, and the fruit Rubus apetalus of provitamin A.
Potentially beneficial effects on healthy aging by supplementation of the EPA-rich microalgae phaeodactylum tricornutum or its supernatant - a randomized controlled pilot trial in elderly individuals
(2022) Stiefvatter, Lena; Frick, Konstantin; Lehnert, Katja; Vetter, Walter; Montoya-Arroyo, Alexander; Frank, Jan; Schmid-Staiger, Ulrike; Bischoff, Stephan C.
Dietary supplements that promote healthy aging are mostly warranted in an aging society. Because of age-related risks, anti-inflammatory and anti-oxidative agents such as microalgae are potential candidates for intervention. In a randomized controlled trial, we tested Phaeodactylum tricornutum (PT), a microalgae rich in eicosapentaenoic acid (EPA), carotenoids, vitamins, and β-glucans, cultured in bioreactors. In this pilot trial, 19 healthy elderly received supplements for two weeks based on either the whole PT (A), the β-1,3-glucan-rich PT supernatant (SupB), the combination thereof (A+SupB), or a Comparator product (Comp). The primary outcome variable plasma interleukin-6 was reduced after treatment with A+SupB compared to the Comp group (p = 0.04). The mobility parameters 5 s sit-to-stand test (p = 0.04 in the A group) and by trend gait speed (p = 0.08 in the A+SupB diet) were improved compared to Comp. No treatment effects were observed for fatty acids, compared to Comp but omega-6 to -3 fatty acid ratio (p = 0.006) and arachidonic acid/EPA ratio (p = 0.006) were reduced within group A+SupB. Further, the SupB study product reduced faecal zonulin (p = 0.03) compared to the Comp. The data revealed an anti-inflammatory and potentially anti-oxidative effect of particular PT preparations, suggesting that they might be suitable for effects in healthy elderly.

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