Ceylon cinnamon (Cinnamomum verum J. Presl) bark essential oil (CBO) represents a promising source of natural bioactive compounds for biological plant protection. For the first time, the antibacterial and antifungal activity of CBO was systematically evaluated against a curated panel of phytopathogenic strains (IOR collection), revealing broad-spectrum efficacy across both bacteria and filamentous pathogens. This study evaluated its chemical composition, antimicrobial activity against phytopathogens, effects on bacterial metabolic activity, and its ability to induce plant defence responses. CBO was dominated by cinnamaldehyde, linalool, and eucalyptol. The oil exhibited strong antibacterial activity against Dickeya dadantii, Pectobacterium carotovorum, Pseudomonas syringae, and Xanthomonas hortorum as well as antifungal activity against Fusarium graminearum, F. culmorum, Rhizoctonia solani and Phytophthora cinnamomi. Metabolic assays revealed a marked reduction in bacterial metabolic activity, indicating that CBO disrupts physiological processes and inhibits growth. In planta experiments showed that foliar application of CBO stimulated PAL activity in wheat leaves without visible phytotoxic symptoms. These findings demonstrate a multifunctional mode of action of CBO, combining direct antimicrobial effects with the elicitation of plant defence responses, and support its potential application in sustainable crop protection.

The increasing evolution of pathogen resistance is a global problem that requires novel solutions. Recently, an increased interest in ethnomedicinal sources can be observed in the derivation of new medicines. The return to traditional medicinal formulations handed down for generations is being followed, but it is necessary to revise them again, taking into account the generally accepted research protocol. We aimed to evaluate the antimicrobial potential of historical deposits of Silesian healing clay (SHC), used in ethnomedicine against Gram-positive bacteria and to assess their biological activity using a primary dermal fibroblast line (NHDF) and a model monocyte line (THP1). Information on medicinal clay deposits that occur in Silesia and are traditionally used in ethnomedicine or ancient medicine and known as terra sigillata Silesiaca or SHC, was selected on available source materials and old prints and maps from the archives of the Polish Geological Institute (Wrocław, Poland). Subsequently, their places of occurrence were identified and traced in the field by taking three deposits from the Silesia territory: Upper Silesia (D1), Opole Silesia (D2), and Lower Silesian (D3) Voivodeships for analysis. Their basic parameters and antimicrobial efficacy against pathogenic bacteria, Gram-positive streptococci and staphylococci, including methicillin-resistant strains, were examined. The study evaluated the effects of clays on growth and vitality using a primary dermal fibroblast line (NHDF) and a monocytic line (THP1). Studies were performed on a cell culture model to determine the effects on tissue regeneration (fibroblasts) and anti-inflammatory effects (monocytes). The study attempted to identify the mechanism of antimicrobial action, especially the textural characteristics and geochemical composition, as well as the environmental reaction (pH). SHCs were classified into the following textural classes: clay loam (D1), clay (D2), and sand (D3). The tested deposits have antimicrobial properties that reduce the bacterial population (10⁴ CFU) compared to the control (10⁸ CFU). The antimicrobial effect depends on the type of clay and the species or strain of bacteria used. In-house studies clearly showed that Staphylococcus aureus Pcm 2054 and Staphylococcus epidermidis MRSE ATCC 2538 cells were completely adsorbed by clay minerals from clay D3.13. Furthermore, 10% leachates also showed an antimicrobial effect, as a reduction in bacterial populations was observed ranging from 91 to 100%. The results showed stimulation of fibroblast culture proliferation and inhibition of the growth of inflammatory cells (monocytes). SHCs tested have antimicrobial potential, in particular D2.7, D2.11, and D3.13. The D3.13 deposit had a bactericidal effect against the staphylococci tested. Aqueous solutions of clays also showed bacteriostatic effect. The results obtained in cell culture model tests indicate properties that modulate the healing process - stimulation of fibroblast growth (NHDF line) and inhibition of monocyte growth (THP1 line).

Solidago gigantea Aiton is an invasive plant species rich in bioactive secondary metabolites. The aim of this study was to characterize the phytochemical profile of an ethanolic S. gigantea extract and to evaluate its antibacterial and chemoprotective potential using in vitro models. Chemical analysis revealed a high content of phenolic compounds, dominated by chlorogenic acid, along with other phenolic acids and flavonoids, including rutin and quercitrin. The extract also contained saponins and a diverse lipophilic fraction composed of long-chain hydrocarbons, alcohols, fatty acids, phytosterols, and triterpenoids. The extract exhibited strong antibacterial activity against Gram-positive bacteria, including methicillin-resistant Staphylococcus strains, while Gram-negative bacteria and yeasts were less susceptible. In cancer cell models, the extract showed selective antiproliferative and cytotoxic effects, particularly in colorectal and breast cancer cell lines, including doxorubicin-resistant phenotypes, with minimal effects on normal fibroblasts. The extract also showed antioxidant and cytoprotective properties, reflected by a reduction in intracellular reactive oxygen species under both basal and oxidative stress conditions. Increased accumulation of rhodamine 123 in resistant cancer cells suggested a potential inhibition of P-glycoprotein-mediated efflux. Overall, the results indicate that S. gigantea extract exhibits multi-target biological activity associated with its polyphenolic composition, supporting its potential application in chemoprevention, adjuvant cancer therapy, and the control of Gram-positive bacterial infections.