Metabolic Changes Induced by Silver Ions in Carlina acaulis

Fractionation of Carlina acaulis L. Root Methanolic Extract as a Promising Path towards New Formulations against Bacillus cereus and Methicillin-Resistant Staphylococcus aureus

The root of Carlina acaulis L. has been widely used in traditional medicine for its antimicrobial properties. In this study, the fractionation of methanol extract from the root was conducted. Four fractions (A, B, C, and D) were obtained and tested against a range of bacteria and fungi. The results showed promising antibacterial activity, especially against Bacillus cereus, where the minimal inhibitory concentration (MIC) was determined to be equal to 0.08 mg/mL and 0.16 mg/mL for heptane (fraction B) and ethyl acetate (fraction C), respectively. In the case of the methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 strain, the same fractions yielded higher MIC values (2.5 and 5.0 mg/mL, respectively). This was accompanied by a lack of apparent cytotoxicity to normal human BJ foreskin fibroblasts, enterocytes derived from CaCo2 cells, and zebrafish embryos. Further analyses revealed the presence of bioactive chlorogenic acids in the fractionated extract, especially in the ethyl acetate fraction (C). These findings support the traditional use of the root from C. acaulis and pave the way for the development of new formulations for treating bacterial infections. This was further evaluated in a proof-of-concept experiment where fraction C was used in the ointment formulation, which maintained high antimicrobial activity against MRSA and displayed low toxicity towards cultured fibroblasts.

Phytochemical Profiling, Antioxidant Activity, and Protective Effect against H2O2-Induced Oxidative Stress of Carlina vulgaris Extract

Carlina vulgaris is a little-understood plant with unexplored biological potential, and the papers regarding its chemical composition are scarce. In our study, for the first time, the phytochemical profile of the plant, focusing on polar metabolites, was established using modern chromatographic techniques including LC-HRMS-QTOF-CAD, UHPLC-PDA-MS. Phytochemical analysis revealed that the species is a rich source of polyphenolic components, with the most abundant being chlorogenic acid and C-glycosides of luteolin, including carlinoside, orientin, isoorientin, and C-glycosides of apigenin, schaftoside, isoschaftoside, and vitexin. Furthermore, we assessed the impact of the polyphenolic-rich fraction of C. vulgaris extracts on human skin fibroblasts using the MTT and NR assays. It was found that the extract was non-toxic and exhibited potent antioxidant activity in the cells subjected to induced oxidative stress. Additionally, it effectively protected the cells against H₂O₂-induced cytotoxicity. Our study contributes to the general trend of searching for new phytotherapeutics with potential applications in pharmacy and medicine. The results indicate that further exploration of C. vulgaris species is worthwhile, as they can serve as valuable plant material for cosmetic use.

Extraction of Isoflavones, Alpha-Hydroxy Acids, and Allantoin from Soybean Leaves-Optimization by a Mixture Design of the Experimental Method

Soybeans are commonly known as a valuable source of biologically active compounds including isoflavones as well as allantoin and alpha-hydroxy acids. Since these compounds exhibit skin therapeutic effects, they are widely used in the cosmetic and pharmaceutical industries. The presented paper shows the optimization of three solvent systems (ethanol, water, and 1,3-propanediol) to increase the extraction efficiency of isoflavones (daidzin, genistin, 6″-O-malonyldaidzin, 6″-O-malonylglycitin, 6″-O-malonylgenistin), allantoin, and alpha-hydroxy acids (citric acid, malic acid) from soybean leaves. A simplex centroid mixture design for three solvents with interior points was applied for the experimental plan creation. Based on the obtained results of metabolite extraction yield in relation to solvent composition, polynomial regression models were developed. All models were significant, with predicted R-squared values between 0.77 and 0.99, while in all cases the model's lack of fit was not significant. The optimal mixture composition enabling the maximization of extraction efficiency was as follows: 32.9% ethanol, 53.9% water, and 13.3% propanediol (v/v/v). Such a mixture composition provided the extraction of 99%, 91%, 100%, 92%, 99%, 70%, 92%, and 69% of daidzin, genistin, 6″-O-malonyldaidzin, 6″-O-malonylglycitin, 6″-O-malonylgenistin, allantoin, citric acid, and malic acid, respectively. The solvent mixture composition developed provides a good extraction efficiency of the metabolites from soybean leaves and high antioxidant properties.

Calcium-enriched biochar modulates cadmium uptake depending on external cadmium dose

The impact of calcium-enriched biochar (BC, containing Ca, Al, Fe and P as dominant elements in the range of 6.9-1.3% with alkaline pH) obtained from sewage sludge (0.1 or 0.5% in the final soil) on cadmium-induced toxicity (final dose of 1.5 mg Cd/kg in control and 4.5 or 16.5 mg Cd/kg soil in low and high Cd treatment) was tested in medicinal plant Matricaria chamomilla. Low Cd dose had typically less negative impact than high Cd dose at the level of minerals and metabolites and the effect of BC doses often differed. Contrary to expectations, 0.5% BC with a high Cd dose increased Cd accumulation in plants about 2-fold. This was reflected in higher signals of reactive oxygen species, but especially the high dose of BC increased the amount of antioxidants (ascorbic acid and non-protein thiols), minerals and amino acids in shoots and/or roots and usually mitigated the negative effect of Cd. Surprisingly, the relationship between BC and soluble phenols was negative at high BC + high Cd dose, whereas the effect of Cd and BC on organic acids (mainly tartaric acid) differed in shoots and roots. Interestingly, BC alone applied to the control soil (1.5 mg total Cd/kg) reduced the amount of Cd in the plants by about 30%. PCA analyses confirmed that metabolic changes clearly distinguished the high Cd + high BC treatment from the corresponding Cd/BC treatments in both shoots and roots. Thus, it is clear that the effect of biochar depends not only on its dose but also on the amount of Cd in the soil, suggesting the use of Ca-rich biochar both for phytoremediation and safer food production.

Effect of metal cations on antimicrobial activity and compartmentalization of silver in Shewanella oneidensis MR-1 upon exposure to silver ions

Silver is an antimicrobial agent that is used extensively in consumer products, such as fabrics and humidifiers. Silver ion (Ag⁺) uptake in bacteria represents a crucial phase of antimicrobial activity. However, the uptake mechanism of Ag⁺ in bacteria remains largely unknown. The genus Shewanella drives many geochemical processes of nutrients and pollutants in soils. In the present study, Ag⁺ uptake by Shewanella oneidensis MR-1 was first investigated in a laboratory in defined anaerobic, oligotrophic, and inorganic media with or without cations (potassium ions [K⁺], magnesium ions [Mg²⁺], and zinc ions [Zn²⁺]). Our results revealed variations in antimicrobial activity of Ag⁺ in the presence of Mg²⁺ and Zn²⁺. First, Mg²⁺ significantly decreased antimicrobial activity of Ag⁺ in S. oneidensis MR-1 by inhibiting cellular Ag⁺ uptake when compared with K⁺. The results were consistent with that of Co²⁺ (Mg²⁺ channel blocker) decreased Ag⁺ uptake by S. oneidensis MR-1. Moreover, Mg²⁺ promoted riboflavin secretion and facilitated the formation of metallic Ag nanoparticles on bacterial surfaces, which was beneficial for extracellular electron transfer and consequently reduced antibacterial activity of Ag⁺. Second, Zn²⁺ increased the antimicrobial activity of Ag⁺ in S. oneidensis MR-1, although the effect on Ag⁺ uptake was minimal. A synergistic interaction between Zn²⁺ and Ag⁺ led to an increase in dead cells and decreased ferrihydrite reduction capacity. The findings suggest that Mg²⁺ could reduce the environmental risk of Ag⁺ to soil bacteria, while Zn²⁺ should be of particular concern due to its synergistic antimicrobial effect on bacteria.

Allantoin overaccumulation enhances production of metabolites under excess of metals but is not tightly regulated by nitric oxide

The aln-3 mutant overaccumulating allantoin and respective wild type (WT) strain of Arabidopsis thaliana were exposed to cadmium (Cd) or mercury (Hg) with or without nitric oxide (NO) donor (sodium nitroprusside, SNP) to study cross-talk, metabolic and oxidative changes between these nitrogen sources (organic vs. inorganic). The aln-3 accumulated over 10-fold more allantoin than WT with the effect of Cd and Hg differing in leaf and root tissue: aln-3 contained more ascorbic acid and phytochelatins when treated with Cd or Hg and more Cd in both organs. SNP depleted leaf Cd and root Hg accumulation in aln3 but had a positive impact on the amount of metabolites typically in WT plants, indicating potentially negative relation between allantoin and NO. In agreement, aln-3 roots showed lower NO signals in control or metal treatments, but higher ROS signal, and SNP had more pronounced impact in WT roots. Flavonol glycosides were more abundant in aln-3 and were affected more by metals than by SNP. Malate was the most affected Krebs acid with strong reaction to SNP and Hg treatment. Data indicate that allantoin overaccumulation influences the accumulation of specific metabolites but nitric oxide has a greater impact on the metabolite profile in WT.

Basic physiology and biochemistry in environmental/experimental plant studies: How to quantify and interpret metabolites correctly

As a reviewer of ca. 50 manuscripts per year submitted to various journals, I often come across questionable metabolic data (both over- or under-estimated) mainly in the journals from the section of Environmental Sciences of Web of Science. Though the trends of visibly incorrect metabolite values may be informative (changes in response to applied treatments or environmental factors), absolute values must be precise enough to allow inter-specific comparison and eventual subsequent calculations. Technical correctness of quantification and calculation of such data is therefore often questionable. One problem arises when calculating metabolites concentration (often nmol or μmol/g of biomass) and another problem is the impact of altered water content on metabolite level (then trend per gram of fresh or dry biomass will differ). Recent discrepancies I found when searching for the literature prompted me to write this technical note aimed at focusing attention of researchers on these problems. I exclude any conflict of interest when discussing the quoted published studies. I strongly urge interested researchers to verify the correctness of metabolite quantification (extraction, dilution/calculation and alternative methods) and also to study similar literature for comparison in order to prevent the spread of incorrect data in the scientific literature.

Back to the Roots-An Overview of the Chemical Composition and Bioactivity of Selected Root-Essential Oils

Since ancient times, plant roots have been widely used in traditional medicine for treating various ailments and diseases due to their beneficial effects. A large number of studies have demonstrated that-besides their aromatic properties-their biological activity can often be attributed to volatile constituents. This review provides a comprehensive overview of investigations into the chemical composition of essential oils and volatile components obtained from selected aromatic roots, including Angelica archangelica, Armoracia rusticana, Carlina sp., Chrysopogon zizanioides, Coleus forskohlii, Inula helenium, Sassafras albidum, Saussurea costus, and Valeriana officinalis. Additionally, their most important associated biological impacts are reported, such as anticarcinogenic, antimicrobial, antioxidant, pesticidal, and other miscellaneous properties. Various literature and electronic databases-including PubMed, ScienceDirect, Springer, Scopus, Google Scholar, and Wiley-were screened and data was obtained accordingly. The results indicate the promising properties of root-essential oils and their potential as a source for natural biologically active products for flavor, pharmaceutical, agricultural, and fragrance industries. However, more research is required to further establish the mechanism of action mediating these bioactivities as well as essential oil standardization because the chemical composition often strongly varies depending on external factors.

Positive effects of metallic nanoparticles on plants: Overview of involved mechanisms

Engineered nanoparticles (NPs) are considered as potential agents for agriculture as fertilizers, growth enhancers and pesticides. Therefore, understanding the mechanisms that are responsible for their effects is important. Various studies demonstrated that the application of nontoxic concentrations can promote seed germination, enhance plant growth and increase the yield. Moreover, NPs can be used to protect plants from environmental impacts such as salt or drought stress and diminish accumulation and toxicity of heavy metals. NPs can serve as a source of micronutrients (e.g. ZnO, iron- and manganese-based NPs), thus increasing fitness and helps plants to cope with stress conditions. TiO₂ and iron-based NPs are able to delay senescence and speed-up cell division via changes in phytohormonal levels. The application of some NPs can promote the activity of enzymes such as amylase, nitrate reductase, phosphatase, phytase and carbonic anhydrases, which are involved in metabolism and nutrient acquisition. E.g. ZnO and TiO₂ NPs can stimulate chlorophyll biosynthesis and photosynthetic activity. Iron-based and CeO₂ NPs enhance stomata opening resulting in better gas exchange and CO₂ assimilation rate. NPs can also modulate oxidative stress by the stimulation of the antioxidant enzymes such peroxidases and superoxide dismutase. However, the knowledge about the fate, transformation, and accumulation of NPs in the environment and organisms is needed prior to their use in agriculture to avoid negative environmental impacts. Higher or lower toxicity of various NPs was established for microorganisms, plants or animals. In this overview, we focused on the possible mechanisms of Ag, ZnO, TiO₂, Fe-based, CeO₂, Al₂O₃, and manganese-based NPs responsible for their positive effects on plants.

Organic nitrogen modulates not only cadmium toxicity but also microbial activity in plants

It is known that organic nitrogen may modify uptake and toxicity of metals but direct metabolic and microbial comparison of various organic N sources is not available. We therefore studied comparative impact of additional N sources (nitrate, urea or allantoin as 1 mM of N for each compound in addition to 15 mM of inorganic N in the Hoagland solution) on Cd toxicity and microbial activity in common crop cucumber. Organic N significantly elevated the growth, chlorophyll content and photosynthetic activity under Cd excess in comparison with inorganic N though the impact on Cd uptake was negligible. Both organic N compounds also affected accumulation of mineral nutrients, total N, amino acids, and protein content in Cd-stressed plants. Among organic acids, mainly allantoin and partially urea affected accumulation of citrate and tartrate. The most notably, we detected that allantoin was decomposed even within 24 h by microbes into the urea, but it significantly elevated rhizosphere microbial activity. All these data indicate that allantoin is metabolized by plants/microbes into the urea and that it affects microbes mainly in the rhizosphere, which could contribute to amelioration of Cd toxicity.

Morphological, Anatomical, and Phytochemical Studies of Carlina acaulis L. Cypsela

Carlina acaulis L. has a long tradition of use in folk medicine. The chemical composition of the roots and green parts of the plant is quite well known. There is the lowest amount of data on the cypsela (fruit) of this plant. In this study, the microscopic structures and the chemical composition of the cypsela were investigated. Preliminary cytochemical studies of the structure of the Carlina acaulis L. cypsela showed the presence of substantial amounts of protein and lipophilic substances. The chemical composition of the cypsela was investigated using spectrophotometry, gas chromatography with mass spectrometry, and high-performance liquid chromatography with spectrophotometric and fluorescence detection. The cypsela has been shown to be a rich source of macro- and microelements, vegetable oil (25%), α-tocopherol (approx. 2 g/kg of oil), protein (approx. 36% seed weight), and chlorogenic acids (approx. 22 g/kg seed weight). It also contains a complex set of volatile compounds. The C. acaulis cypsela is, therefore, a valuable source of nutrients and bioactive substances.

Toxicity of Carlina Oxide-A Natural Polyacetylene from the Carlina acaulis Roots-In Vitro and In Vivo Study

There are several reports indicating that the roots of the Carlina acaulis L. used to be commonly applied as a treatment measure in skin diseases and as an antiparasitic agent, starting from antiquity to the 19th century; however, nowadays, it has lost its importance. Currently, numerous studies are being conducted assessing the possibility of reintroducing C. acaulis-derived extracts to phytotherapy. Determining the safety profile of the main constituents of the plant material is crucial for achieving this goal. Here, we aimed to determine the toxicity profile of carlina oxide, one of the most abundant components of the C. acaulis root extract. We obtained the carlina oxide by distillation of C. acaulis roots in the Deryng apparatus. The purity of the standard was evaluated using GC-MS, and the identity was confirmed by IR, Raman, and NMR spectroscopy. In vitro cytotoxicity was assessed using a panel of human cell lines of skin origin, including BJ normal fibroblasts and UACC-903, UACC-647, and C32 melanoma cells. This was accompanied by an in vivo zebrafish acute toxicity test (ZFET). In vitro studies showed a toxic effect of carlina oxide, as demonstrated by an induction of apoptosis and necrosis in both normal and melanoma cells. Decreased expression of AKT kinase and extracellular signal-regulated kinase 1/2 (ERK1/2) was noted in the UACC-647 melanoma cell line. It was also observed that carlina oxide modified the expression of programmed cell death-ligand 1 (PD-L1) in tested cell lines. Carlina oxide exhibited high in vivo toxicity, with LC₅₀ = 10.13 µg/mL upon the 96 h of exposure in the ZFET test. Here, we demonstrate that carlina oxide displays toxic effects to cells in culture and to living organisms. The data indicate that C. acaulis-based extracts considered for therapeutic use should be completely deprived of carlina oxide.

The Impact of Different Cultivation Systems on the Content of Selected Secondary Metabolites and Antioxidant Activity of Carlina acaulis Plant Material

Roots and leaves of Carlina acaulis L. are still used in ethnomedicine in many European countries; however, the limited occurrence of the plants and protection of this species necessitate a search for alternative ways for obtaining this plant material. In this study, in vitro cultures, hydroponic cultures, and field cultivation were applied to obtain the C. acaulis plant material. Its quality was evaluated using antioxidant activity tests and high performance liquid chromatography analysis. Our study showed that the antioxidant activity and the content of chlorogenic and 3,5-di-caffeoylquinic acid in roots of plants cultivated in hydroponics and field conditions were comparable. However, the amount of carlina oxide was significantly higher in plants from the field. The flavonoid content in leaves obtained from both cultivation systems was at the same level; however, the antioxidant activity and the content of the investigated metabolites were higher in the soil cultivation system. The callus line exhibited high differentiation in phytochemical compositions depending on the treatments and medium compositions.