Stephan Plattner

Background/Objectives: Seasonal waves of respiratory viruses—including SARS-CoV-2, influenza A virus (IAV), and respiratory syncytial virus (RSV)—continue to pose a global health burden and highlight the need for antiviral agents that are effective, safe, broadly active, affordable, and widely accessible. Current interventions are limited by the need for their early administration, the risk of resistance, their costs, and the restricted availability in large parts of the world. For certain natural products, such as European black elderberry (Sambucus nigra L.) fruit extract (ElderCraft^®; EC) and the seaweed-derived sulfated polymer iota-carrageenan (IC), antiviral activities against respiratory viruses, particularly IAV and SARS-CoV-2, have previously been shown. Here, we assessed the antiviral activity of IC and an anthocyanin-standardized EC extract against SARS-CoV-2, IAV, and RSV, either as monotherapy or in multiple-dose combinations. Methods: MDCKII cells were infected with IAV_PR8, human Calu-3 lung epithelial cells with the SARS-CoV-2 Omicron variant, and HEp-2 cells with RSV (A2 strain). Inhibitors were administered either by pre-incubation of cell-free virions prior to infection or, in separate time-of-addition experiments, during or post-infection. Viral replication was quantified by qRT-PCR or intracellular immunostaining. Cytotoxicity was evaluated using a neutral red uptake assay. Results: Most intriguingly, both EC and IC are able to neutralize virions derived from SARS-CoV-2, IAV, or RSV extracellularly in a dose-dependent manner. Notably, EC and IC alone exhibited strong anti-RSV activity, which was not reported previously. Most importantly, combined treatment with IC and EC caused a pronounced synergistic antiviral effect against the tested viruses, as confirmed by the Bliss independence model, without any detectable impact on cell viability. Finally, solutions prepared from matrix-standardized mono- or combi-lozenges, containing IC and/or EC in high or low doses, reproduced the antiviral and synergistic combination effects observed with the pure compounds. Conclusions: In summary, these findings support further development of EC and IC as a topically accessible, virion-neutralizing combination (e.g., lozenges) to provide additional protection against major respiratory viruses and potentially strengthen pandemic preparedness.

Polyphenol-rich fruits represent promising natural candidates for mitigating oxidative stress. We determined in dose–response manner the intracellular antioxidant activities of P. cerasus (tart cherry) extract in HepG2 cells using three different cellular assays targeting specific mechanisms of action: (1) the AOP1 assay, to assess intracellular ROS scavenging activity; (2) the CAA assay, to estimate ROS scavenging activity at the cell membrane; and (3), the HepG2-ARE-luc assay, to evaluate Antioxidant Response Element (ARE) pathway modulation. Tart cherry extract exhibited a high and concentration-dependent intracellular ROS scavenging activity with the AOP1 assay (EC₅₀ of 72.02 µg/mL), whereas antioxidant efficacy measured via the CAA assay was much lower (EC₅₀ of 6.975 mg/mL). Notably, P. cerasus extract did not activate the ARE-driven luciferase gene expression. Instead, the extract induced a clear dose-dependent repression of ARE-driven transcriptional activity, with a reduction in luciferase gene expression ranging from 20 to 70% across the sample tested concentrations (0.38–98 µg/mL). These findings suggest that, at concentrations where it functions as a potent intracellular ROS scavenger, P. cerasus extract exerts a negative regulation of the ARE pathway. Further investigations are warranted to elucidate the compounds underlying these effects.

Background/Objectives: The persistent threat of emerging respiratory RNA viruses like SARS-CoV-2 and Influenza A virus (IAV) necessitates the continuous development of effective, safe, broadly acting, and generally accessible antiviral agents. Current treatments often face limitations such as early administration requirements, resistance development, and limited global access. Natural products, like European black elderberry (Sambucus nigra L.; S. nigra) fruit extract and quinine, have been used historically against viral infections. In this study, we investigated the antiviral efficacy of a standardized black elderberry fruit extract containing 3.2% anthocyanins (EC 3.2) and, as a second natural antiviral product, quinine, against IAV and SARS-CoV-2 in vitro. Methods: Madin–Darby Canine Kidney II (MDCKII) cells were infected with IAV PR-8, while human Calu-3 lung epithelial cells were infected with Wuhan-type SARS-CoV-2. Cells were treated with varying concentrations of EC 3.2 and quinine either as mono- or combinational therapy. Viral replication was assessed using quantitative RT-PCR, and cell viability was evaluated using WST-1 assays. Results: Our results demonstrate, for the first time, that both EC 3.2 and quinine individually inhibited IAV replication in a dose-dependent manner, with IC₅₀ values of approximately 1:400 for EC 3.2 and 250 nM for quinine. Most importantly, the combinational treatment exhibited a strong synergistic antiviral effect, as confirmed by the Bliss independence model (synergy scores of 14.7 for IAV, and 27.8 for SARS-CoV-2), without affecting cell viability. Conclusions: These findings suggest that the combined use of black elderberry extract and quinine might serve as an effective antiviral strategy against IAV and SARS-CoV-2, particularly since the synergistic effect allows for lower doses of each product while retaining therapeutic efficacy. In summary, this combinational in vitro approach, when expanded to other respiratory RNA viruses and confirmed in clinical studies, has the potential to open a promising avenue for pandemic preparedness.

The persistent threat of emerging respiratory RNA viruses like SARS-CoV-2 and Influenza A virus (IAV) necessitates the continuous development of effective, safe, broadly acting and gener-ally accessible antiviral agents. Current treatments often face limitations such as early admin-istration requirements, resistance development, and limited global access. Natural products like European black elderberry (Sambucus nigra L.) fruit extract and quinine have been used histori-cally against viral infections. In this study, we investigated the antiviral efficacy of a standard-ized black elderberry fruit extract containing 3.2 % anthocyanins (EC 3.2) and, as a second natu-ral antiviral product, quinine, against IAV and SARS-CoV-2 in vitro. Madin-Darby Canine Kid-ney II (MDCKII) cells were infected with IAV PR-8, while human Calu-3 lung epithelial cells were infected with SARS-CoV-2 Wuhan type. Cells were treated with varying concentrations of EC 3.2 and quinine as either mono– or combinational therapy. Viral replication was assessed using quantitative RT-PCR, and cell viability was evaluated using WST-1 assays. Our results demonstrate for the first time that both EC 3.2 and quinine individually inhibited IAV replica-tion in a dose-dependent manner, with IC₅₀ values of approximately 1:400 for EC 3.2 and 250 nM for quinine. Most importantly, the combinational treatment exhibited a strong synergistic anti-viral effect, as confirmed by the Bliss independence model (synergy scores of 14.7 for IAV and 27.8 for SARS-CoV-2) without affecting cell viability. These findings suggest that the combined use of black elderberry extract and quinine may serve as an effective antiviral strategy against IAV and SARS-CoV-2. The synergistic effect allows for lower doses of each product while keep-ing therapeutic efficacy. In summary, this combinational approach should be expanded to other respiratory RNA viruses, and thus might offer a promising avenue for pandemic preparedness. Moreover, the in vitro data obtained in this study have to be confirmed in clinical studies.

Evidence suggests that tart cherry (TC) supplementation has beneficial effects on health indices and recovery following strenuous exercise. However, little is known about the mechanisms and how TC might modulate the human metabolome. The aim of this study was to evaluate the influence of an acute high- and low-dose of Vistula TC supplementation on the metabolomic profile in humans. In a randomised, double-blind, placebo controlled, cross-over design, 12 healthy participants (nine male and three female; mean ± SD age, stature, and mass were 29 ± 7 years old, 1.75 ± 0.1 m, and 77.3 ± 10.5 kg, respectively) visited the laboratory on three separate occasions (high dose; HI, low dose; LO, or placebo), separated by at least seven days. After an overnight fast, a baseline venous blood sample was taken, followed by consumption of a standardised breakfast and dose conditions (HI, LO, or placebo). Subsequent blood draws were taken 1, 2, 3, 5, and 8 h post consumption. Following sample preparation, an untargeted metabolomics approach was adopted, and the extracts analysed by LCMS/MS. When all time points were collated, a principal component analysis showed a significant difference between the conditions (p < 0.05), such that the placebo trial had homogeneity, and HI showed greater heterogeneity. In a sub-group analysis, cyanidine-3-O-glucoside (C3G), cyanidine-3-O-rutinoside (C3R), and vanillic acid (VA) were detected in plasma and showed significant differences (p < 0.05) following acute consumption of Vistula TC, compared to the placebo group. These results provide evidence that phenolics are bioavailable in plasma and induce shifts in the metabolome following acute Vistula TC consumption. These data could be used to inform future intervention studies where changes in physiological outcomes could be influenced by metabolomic shifts following acute supplementation.

Coronavirus disease-19 (COVID-19) is still affecting the lives of people round the globe and remains a major public health threat. The emergence of new variants more efficiently transmitted, more virulent and more capable of escaping naturally acquired and vaccine-induced immunity creates a long-term negative outlook for the management of the pandemic. The development of effective and viable prevention and treatment options to reduce viral transmission is of the utmost importance. The fruits of the European black elderberry and extracts thereof have been traditionally used to treat viral infections such as coughs, cold and flu. Specifically, its efficacy against the Influenza A virus has been shown in vitro as well as in human clinical trials. In the current project, we investigated the antiviral activity of a black elderberry extract, mainly containing anthocyanins and phenolic compounds, against SARS-CoV-2 and its variants of concern and explored the possible mode of action by performing time of addition experiments. The results revealed that the extract displayed a strong anti-SARS-CoV-2 activity against the Wuhan type as well as the variants of concern Alpha, Beta, Gamma, Delta and Omicron with a comparable antiviral activity. Based on cytotoxicity data, a 2-log theoretical therapeutic window was established. The data accumulated so far suggest that the viral replication cycle is inhibited at later stages, inasmuch as the replication process was affected after virus entry. Therefore, it would be legitimate to assume that black elderberry extract might have the potential to be an effective treatment option for SARS-CoV-2 infections.

(1) Background: The intestinal microbiome has emerged as a central factor in human physiology and its alteration has been associated with disease. Therefore, great hopes are placed in microbiota-modulating strategies. Among various approaches, prebiotics, substrates with selective metabolization conferring a health benefit to the host, are promising candidates. Herein, we studied the prebiotic properties of a purified extract from European black elderberries, with a high and standardized content of polyphenols and anthocyanins. (2) Methods: The ELDERGUT trial represents a 9-week longitudinal intervention study divided into 3 distinct phases, namely a baseline, an intervention and a washout period, three weeks each. The intervention consisted of capsules containing 300 mg elderberry extract taken twice a day. Patient-reported outcomes and biosamples were collected weekly. Microbiome composition was assessed using 16S amplicon metagenomics. (3) Results: The supplementation was well tolerated. Microbiome trajectories were highly individualized with a profound shift in diversity indices immediately upon initiation and after termination of the compound. This was accompanied by corresponding changes in species abundance over time. Of particular interest, the relative abundance of Akkermansia spp. continued to increase in a subset of participants even beyond the supplementation period. Associations with participant metadata were detected.

European black elderberry (Sambucus nigra L.) is a popular way to treat common colds or influenza infections. Mechanistically, this might be due to a direct antiviral effect or a stimulatory effect on the immune system of the host. Here, we evaluated the modulatory effects of black elderberry derived water extract (EC15) and its polysaccharide enriched fractions (CPS, BOUND, and UNBOUND) in comparison to a conventional alcoholic extract (EE25), regarding the phenotypical and functional properties of dendritic cells (DCs), which are essential cells to induce potent T cell responses. Interestingly, the water extract and its polysaccharide fractions potently induced DC maturation, while the ethanol extract did not. Moreover, the capacity to stimulate T cells by these matured DCs, as assessed using MLR assays, was statistically higher when induced by the water extracted fractions, compared to immature DCs. On the other hand, the ethanol extract EE25 did not induce T cell stimulation. Finally, the cytokine expression profiles of these DC—T cell cocultures were assessed and correlated well with increased T cell stimulation. Also, the expression of inflammatory cytokines, such as IL-6, TNF-α, and IFN-γ was highly increased in the presence of the elderberry water extract EC15, and the polysaccharide enriched CPS, BOUND, and UNBOUND fractions, but not by EE25. Thus, from these data, we conclude that the polysaccharides present in water-derived elderberry fractions induce potent immune-modulatory effects, which represents the basis for a strong immune-mediated response to viruses including influenza.