Quality parameters for the medicinal plant Drosera rotundifolia L.: A new approach with established techniques.

Monographs of the European Pharmacopoeia (Ph. Eur.) are the basis for quality control of medicinal plants and therefore important to ensure the consistency, quality, safety, and efficacy of phytopharmaceuticals. The traditional medicinal plant sundew (Drosera sp.) has disappeared from therapy due to nature conservation, but can now be cultivated sustainably on rewetted peatland. However, currently there is no valid Ph. Eur. monograph for the quality control of Droserae herba. In this study, sundew material from different species and sources was investigated with the aim of developing quality control methods based on the Ph. Eur. and defining a uniform quality standard for Droserae herba. It was possible to distinguish between sundew species of different quality, using macroscopic, microscopic, and chromatographic methods. Special emphasis was laid on the content of flavonoids and naphthoquinones as important quality parameters as their content differed between the sundew species. The differences in content and toxicity result in the recommendation that only round-leaved sundew (Drosera rotundifolia L.) should be used as a medicinal plant for the production of phytopharmaceuticals in the future.

The potential of Ethiopian medicinal plants to treat emergent viral diseases.

Ethiopians have deep-rooted traditions of using plants to treat ailments affecting humans and domesticated animals. Approximately 80% of the population continues to rely on traditional medicine, including for the prevention and treatment of viral diseases. Many antiviral plants are available to and widely used by communities in areas where access to conventional healthcare systems is limited. In some cases, pharmacological studies also confirm the potent antiviral properties of Ethiopian plants. Building on traditional knowledge of medicinal plants and testing their antiviral properties may help to expand options to address the global pandemic of COVID-19 including its recently isolated virulent variants and prepare for similar outbreaks in the future. Here, we provide an ethnobotanical and pharmacological inventory of Ethiopian medicinal plants that might contribute to the prevention and treatment of viral diseases. We identified 387 species, about 6% of Ethiopia's known flora, for which records of use by local communities and traditional herbalists have been documented for the treatment of viral diseases. We provide a framework for further investigation and development of this vital resource much anticipated to help combat emergent viral diseases along with existing ones in Ethiopia and elsewhere.

Antibiofilm Activity of Sundew Species against Multidrug-Resistant Escherichia coli Strains.

Species of the genus Drosera, known for carnivorous plants, such as sundew, have been traditionally used for centuries as medicinal plants. Efficacy-determining compounds are naphthoquinones and flavonoids. Flavonoids possess a broad spectrum of bioactive properties, including biofilm inhibitory activity. Biofilms render antibiotics ineffective, contributing to the current rise in antimicrobial resistance. In this study, the biofilm inhibitory activity of two European sundew species (Drosera rotundifolia and Drosera intermedia) grown agriculturally in Germany and four commercial sundew products (declared as Drosera longifolia, Drosera sp. and Drosera planta trit.) against three multidrug-resistant Escherichia coli strains was tested. The aim of the study was to comparatively investigate the biofilm inhibitory potential of sundew species extracts grown locally in northern Germany and commercial sundew products. The minimum biofilm inhibitory concentration of the European sundew species was approx. 35 µg mL-1. In comparison, commercial sundew products ranged in concentration from 75 to 140 µg mL-1. Additionally, individual compounds isolated from European sundew were tested. Among these compounds, biofilm inhibitory activity was determined for four of the eight substances, with 2″-O-galloyl hyperoside standing out for its activity (38 µg mL-1). The whole plant extracts of Drosera rotundifolia and Drosera intermedia proved to be more effective than the commercial products and the single compounds in its biofilm inhibition activity against Escherichia coli strains. Sundew extracts may serve as a potential therapeutic approach for targeting biofilm production.

Evaluating Tannins and Flavonoids from Traditionally Used Medicinal Plants with Biofilm Inhibitory Effects against MRGN E. coli.

In the search for alternative treatment options for infections with multi-resistant germs, traditionally used medicinal plants are currently being examined more intensively. In this study, the antimicrobial and anti-biofilm activities of 14 herbal drugs were investigated. Nine of the tested drugs were traditionally used in Europe for treatment of local infections. For comparison, another five drugs monographed in the European Pharmacopoeia were used. Additionally, the total tannin and flavonoid contents of all tested drugs were analyzed. HPLC fingerprints were recorded to obtain further insights into the components of the extracts. The aim of the study was to identify herbal drugs that might be useable for treatment of infectious diseases, even with multidrug resistant E. coli, and to correlate the antimicrobial activity with the total content of tannins and flavonoids. The agar diffusion test and anti-biofilm assay were used to evaluate the antimicrobial potential of different extracts from the plants. Colorimetric methods (from European Pharmacopeia) were used for determination of total tannins and flavonoids. The direct antimicrobial activity of most of the tested extracts was low to moderate. The anti-biofilm activity was found to be down to 10 µg mL−1 for some extracts. Tannin contents between 2.2% and 10.4% of dry weight and total flavonoid contents between 0.1% and 1.6% were found. Correlation analysis indicates that the antimicrobial and the anti-biofilm activity is significantly (p < 0.05) dependent on tannin content, but not on flavonoid content. The data analysis revealed that tannin-rich herbal drugs inhibit pathogens in different ways. Thus, some of the tested herbal drugs might be useable for local infections with multi-resistant biofilm-forming pathogens. For some of the tested drugs, this is the first report about anti-biofilm activity, as well as total tannin and flavonoid content.

TRAP transporter TakP: a key player in the resistance against selenite-induced oxidative stress in Rhodobacter sphaeroides.

Almost one-third of all proteins require metal ions as an essential component in key biological processes and approximately half of all enzymes are associated with one or more metal ions. The naturally occurring selenium is very toxic at higher levels, but few bacteria can reduce it into the less toxic insoluble elemental selenium. Selenium is required for the synthesis of selenocysteine, an essential residue involved in the active sites of various enzymes. The purple non-sulphur bacteria, Rhodobacter sphaeroidesis demonstrated for its selenite reduction capacity. The exact mechanism of selenite toxicity is unknown but it reacts with glutathione to form selenodiglutathione, producing the highly toxic compounds namely, H2O2and O2-. A R. sphaeroidesstrain with mutated takP gene, a member of the TRAP (tripartite ATP-independent periplasmic) family of transporter, was reported to be showing more resistance towards selenite in the growth medium but the reason for the resistance is unknown. TRAP transporters are the best-studied family of substrate-binding protein and in our previous study it was confirmed that the gene takP in R. sphaeroides is down-regulated by a small non-coding RNA SorY, providing more resistance to the bacterium against the oxidative stress. By comparative growth analysis and sensitivity assays in the presence of 2 mM selenite, it was observed that the SorY knockout strain is more sensitive to selenite while overexpression of the sRNA conferred more resistance to the bacterium like the takP mutant strain. TakP is involved in the import of malate into the cell, which under oxidative stress needs to be down-regulated to limit malate flux into the cell. Limited malate flux leads to metabolic rearrangements in the cell to avoid excessive generation of prooxidant NADH and facilitate constant generation of antioxidant NADPH. In the presence and absence of selenite, a drastic increase in the NADPH and decrease in the NADH levels are reported respectively. Accumulation of metallic selenium in the cytoplasm was detected via atomic absorption spectrophotometer and our analysis clearly demonstrated the presence of more selenium in the electron micrographs of the SorY knockout strain compared to the takP mutant grown under dark semi-aerobic growth conditions in the presence of selenite. Hence based on our analysis, it is confirmed that lack of TakP transporter led to reduced selenite influx into the cytoplasm, relieving cells with limited generation of ROS, eventually exhibiting more resistance against selenite-induced oxidative stress.

Ethiopian Medicinal Plants Traditionally Used for the Treatment of Cancer; Part 3: Selective Cytotoxic Activity of 22 Plants against Human Cancer Cell Lines.

Medicinal plants have been traditionally used to treat cancer in Ethiopia. However, very few studies have reported the in vitro anticancer activities of medicinal plants that are collected from different agro-ecological zones of Ethiopia. Hence, the main aim of this study was to screen the cytotoxic activities of 80% methanol extracts of 22 plants against human peripheral blood mononuclear cells (PBMCs), as well as human breast (MCF-7), lung (A427), bladder (RT-4), and cervical (SiSo) cancer cell lines. Active extracts were further screened against human large cell lung carcinoma (LCLC-103H), pancreatic cancer (DAN-G), ovarian cancer (A2780), and squamous cell carcinoma of the esophagus (KYSE-70) by using the crystal violet cell proliferation assay, while the vitality of the acute myeloid leukemia (HL-60) and histiocytic lymphoma (U-937) cell lines was monitored in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) microtiter assay. Euphorbia schimperiana, Acokanthera schimperi, Kniphofia foliosa, and Kalanchoe petitiana exhibited potent antiproliferative activity against A427, RT-4, MCF-7, and SiSo cell lines, with IC50 values ranging from 1.85 ± 0.44 to 17.8 ± 2.31 µg/mL. Furthermore, these four extracts also showed potent antiproliferative activities against LCLC-103H, DAN-G, A2780, KYSE-70, HL-60, and U-937 cell lines, with IC50 values ranging from 0.086 to 27.06 ± 10.8 µg/mL. Hence, further studies focusing on bio-assay-guided isolation and structural elucidation of active cytotoxic compounds from these plants are warranted.

The broader context of antibiotic resistance: zinc feed supplementation of piglets increases the proportion of multi-resistant Escherichia coli in vivo.

Following the Europe-wide ban of antimicrobial growth promoters, feed supplementation with zinc has increased in livestock breeding. In addition to possible beneficial effects on animal health, feed supplementation with heavy metals is known to influence the gut microbiota and might promote the spread of antimicrobial resistance via co-selection or other mechanisms. As Escherichia coli is among the most important pathogens in pig production and often displays multi-resistant phenotypes, we set out to investigate the influence of zinc feed additives on the composition of the E. coli populations in vivo focusing on phylogenetic diversity and antimicrobial resistance. In a piglet feeding trial, E. coli were isolated from ileum and colon digesta of high dose zinc-supplemented (2500ppm) and background dose (50ppm) piglets (control group). The E. coli population was characterized via pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) for the determination of the phylogenetic background. Phenotypic resistance screening via agar disk diffusion and minimum inhibitory concentration testing was followed by detection of resistance genes for selected clones. We observed a higher diversity of E. coli clones in animals supplemented with zinc compared to the background control group. The proportion of multi-resistant E. coli was significantly increased in the zinc group compared to the control group (18.6% vs. 0%). For several subclones present both in the feeding and the control group we detected up to three additional phenotypic and genotypic resistances in the subclones from the zinc feeding group. Characterization of these subclones suggests an increase in antimicrobial resistance due to influences on plasmid uptake by zinc supplementation, questioning the reasonability of zinc feed additives as a result of the ban of antimicrobial growth promoters.