This study reports the effects of aqueous extracts obtained from three fern species of Bulgarian origin: Asplenium ceterach L., Asplenium scolopendrium L., and Asplenium trichomanes L. on the contractility and bioelectrogenesis of rat gastric smooth muscle tissues. In the concentration range 0.015–0.150 mg/mL the three extracts contracted smooth muscle tissues in a concentration-dependent manner. The contractions caused by A. ceterach L. and A. scolopendrium L. extracts (0.150 mg/mL) were reduced by ketanserin (5 × 10 −7 and 5 × 10 −6 mol/L), an antagonist of serotonin 5-HT2 receptor. The contraction evoked by A. trichomanes L. (0.150 mg/mL) was significantly reduced by 1 × 10 −6 mol/L atropine, an antagonist of muscarinic receptors, and turned into relaxation against the background of 3 × 10 −7 mol/L galantamine. After combined pretreatment with galantamine and l -arginine (5 × 10 −4 mol/L), this relaxation become more pronounced. The study demonstrates that constituents of A. ceterach L. and A. scolopendrium L. extracts act as agonists of 5-HT2 receptors and cause contraction by activating serotonergic signaling system. A. trichomanes L.-induced reaction is an additive result of two opposite-in-character effects. The dominant contraction is initiated by inhibition of acetylcholinesterase activity. The relaxation develops with pre-inhibited acetylcholinesterase, it is significantly potentiated by l -arginine, and therefore associated with nitrergic signaling pathway.

The ferns Asplenium ceterach L., Asplenium scolopendrium L. and Asplenium trichomanes L. have wide application in traditional medicine worldwide. However, the scientific research on their anticancer and antibacterial properties is insufficient. The present article aims to provide more information on this topic. Extracts derived from the aerial parts of A. ceterach, A. scolopendrium and A. trichomanes were examined using a panel of in vitro assays with different bacterial and mammalian cells. The cytotoxicity and anticancer activity of the samples were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Trypan blue assays with three human (A549, FL, HeLa) and three murine (3T3, TIB-71, LS48) cell lines. Inhibitory effects on the growth of Gram-positive (Bacillus cereus) and Gram-negative (Pseudomonas aeruginosa) bacteria were determined by the agar diffusion assay. Apoptosis-inducing properties of the extracts were analyzed by flow cytometry. Superoxide dismutase (SOD) activity in extract-treated cells was investigated by ELISA. The obtained results demonstrate selective anticancer activity of all three Asplenium species. The extract from A. ceterach displayed the strongest inhibitory properties against human cervical cancer cells and bacterial cells. It induced a lower level of cytotoxicity against mouse cell lines, indicating a species-specific effect. The extract from A. trichomanes demonstrated better anticancer and antibacterial properties than the sample from A. scolopendrium. Further experiments linked the mechanism of action of A. ceterach extract with oxidative stress-inducing potential and strong proapoptotic potential against the cervical cancer cell line HeLa. A. trichomanes and A. scolopendrium extracts appeared to be potent inducers of necrotic cell death.

Background: Ferns are underestimated as medicinal plants and their use in traditional medicine is limited despite their diversity. Most of the research on their healing properties and phytochemical composition related to their biological activity has been focused on the secondary metabolites synthesized by ferns. Objective: In this study, we aimed to make an in-depth chemical characterization of three ferns widely spread in Bulgaria - Asplenium ceterach L., Asplenium scolopendrium L. and Asplenium trichomanes L. Methods: Micro elemental analysis was carried out using ICP-MS. Standard laboratory methods were used to determine the content of proteins, fats and fatty acids. Chromatographic methods were applied to quantify some secondary metabolites. Two antioxidant methods and two antimicrobial tests were used to evaluate the biological properties of the ferns tested. Results: Micro elemental analysis showed that these ferns could be useful source of zinc and iron. Protein content slightly varied among the species (13.6% - 18.4% of the dried plant weight). Negligible was the variation in oil content (3.1% - 4.0%, dry weight base); oil composition was dominated by saturated fatty acids. Some principal classes secondary metabolites, individual phenolic acids and flavonoids were quantified. The extract obtained from Asplenium ceterach L. demonstrated the highest antioxidant capacity. Fern extracts showed moderate antimicrobial activity against six of the 14 microorganisms tested. Conclusion: The results obtained may reveal new areas of application for ferns and are a solid basis for comparison with the same species growing in other geographical and climatic conditions, which may affect their healing properties.

Centaurea thracica (Janka) Hayek is a plant common in southern Bulgaria. The inflorescences were collected during June and September 2021, while their seeds were obtained in September 2021. The chemical and lipid composition of the inflorescences during the vegetation process of the plant were established. A significant decrease in total proteins (from 8.7 to 7.4%), glyceride oils (2.0–1.7%), and ash (4.5–4.2%) content was observed, while the amount of carbohydrates (72.3–77.2%) and fibers (28.7–35.8%) increased. During the vegetation of the plant, the content of oleic and linoleic acids increased up to 2–3 times, while the level of palmitic acid decreased. The lipids from the seeds were rich in oleic (53.0%) and palmitic (36.2%) acids. The tocopherol content in the oils of the inflorescences during vegetation increased from 58 to 110 mg/kg, and the content in the oil from the seeds was 260 mg/kg. The phospholipid content decreased during vegetation, and differences were observed in the composition between the inflorescences and the seeds. The high content of oleic acid, linoleic acid, tocopherols, and phospholipids determine the nutritional and biological value of the oils isolated from Centaurea thracica, and contribute to their potential use in various directions.