Cancer remains a major global health challenge, prompting the search for natural therapeutic agents with selective anticancer activity. This study investigated extracts from 12 medicinal plant species (a total of 21 samples) rich in phenolic compounds, particularly ellagic acid and its derivatives, to evaluate their antioxidant properties and ability to inhibit cancer cell viability. Spectrometric analysis and high-performance liquid chromatography (HPLC) with electrochemical detection (ED) and ultraviolet–visible (UV-VIS) detection were used for compound identification. The anticancer activity of plant extracts was tested using the MTS cell proliferation assay to determine anticancer activity on 4T1, A549, Caki-1, HCT116, and MCF7 cancer cell lines. The HEK-293 healthy cell line was used to determine extracts cytotoxicity. Study results indicate that black walnut (Juglans nigra L.), fireweed (Chamaenerion angustifolium L.), and pedunculate oak (Quercus robur L.) have the highest contents of bioactive compounds. Among tested extracts, fireweed showed the lowest IC₅₀ values, thus the strongest anticancer activity against 4T1 cells (IC₅₀ = 0.28 ± 0.01 RE (rutin equivalents) mg/g), while black walnut was most effective against Caki-1 and HCT116 (IC₅₀ = 1.56 ± 0.01; 2.56 ± 0.02 RE mg/g). IC₅₀ values are reported in rutin equivalents (RE) to maintain consistency with antioxidant normalization parameters used throughout the study. Extended incubation increased anticancer activity across most medicinal plant extracts, with fireweed and Canadian goldenrod demonstrating rapid and sustained potency already at 24 h. After 72 h, the most active fireweed extract inhibited approximately 104–190 million cancer cells per gram of dried plant material, demonstrating substantial antiproliferative activity consistent with the IC₅₀ findings. Importantly, none of the extracts showed cytotoxicity to healthy HEK-293 cells. Overall, the findings highlight several plant species with significant anticancer potential, underscoring their promise as sources of natural bioactive compounds for future cancer prevention and treatment research.

The study evaluates different preparation methods for identifying the best strategy for extracting biologically active compounds from raw Chamaenerion angustifolium (L.) Holub plant material. The methodologies include direct aqueous methanol extraction with a combination of natural aerobic and anaerobic fermentation for 24–72 h, followed by 35 °C and 60 °C drying. Furthermore, the study also focuses on determining the different temperature storage conditions on the stability of biologically active compounds. UV-VIS spectroscopy was used to quantitatively evaluate the total content of phenolic compounds, flavonoids, and radical scavenging activity. For qualitative analysis, chromatographic separation with electrochemical detection (ED) of extracted compounds, a gradient high-performance liquid chromatography (HPLC) system was used. Study results indicate that 48 h natural aerobic fermentation followed by 35 °C drying and 75% (v/v) aqueous methanol extraction yielded the maximum amount of biologically active compounds in Chamaenerion angustifolium (L.) Holub leaves, blossom, and stem samples. Freezing samples in liquid nitrogen had the lowest impact on the total content of phenolic compounds, flavonoids, and radical scavenging activity. HPLC-ED system results identified chlorogenic acid, oenothein B, trans-p-Coumaric acid, ellagic acid, and rutin in Chamaenerion angustifolium (L.) Holub leave samples.

This paper introduces a novel contactless single-chip detector that utilizes impedance-to-digital conversion technology to measure impedance in the microfluidic channel or capillary format analytical device. The detector is designed to operate similarly to capacitively coupled contactless conductivity detectors for capillary electrophoresis or chromatography but with the added capability of performing frequency sweeps up to 200 kHz. At each recorded data point, impedance and phase-shift data can be extracted, which can be used to generate impedance versus frequency plots, or phase-shift versus frequency plots. Real and imaginary parts can also be calculated from the data, allowing for the generation of Nyquist diagrams. This detector represents the first of its kind in the contactless conductivity class to provide spectrum-type data, as demonstrated in capillary electrophoresis experiments.

Medicinal plants are a rich source of biologically active compounds, including phenolic acids, flavonoids, ellagitannins and other secondary metabolites. However, the contribution of specific groups of phenolic compounds to antiproliferative activity remains insufficiently clarified. This study extends our previous crude-extract screening by evaluating whether C18 solid-phase extraction (SPE) fractions with different phenolic profiles are associated with different antiproliferative responses. In parallel, extraction strategies were compared to assess method-dependent changes in phenolic recovery and antioxidant capacity, and an additional single-species vegetation-stage analysis of Chamaenerion angustifolium L. Holub was performed to evaluate harvest-stage effects. Phytochemical characterisation was performed using spectrophotometric assays and high-performance liquid chromatography (HPLC) analyses. Among the tested extraction methods, 75% (v/v) methanol in water was the most effective conventional solvent, and ultrasound-assisted extraction yielded the highest overall TPC (total phenolic content), TFC (total flavonoid content), and RSA (radical scavenging activity) values. Vegetation stage analysis of C. angustifolium L. Holub revealed significant variation in phenolic content and antioxidant activity, with the highest levels observed at the beginning of the flowering. Antiproliferative activity was assessed against five cancer cell lines (4T1, A549, Caki-1, HCT116 and MCF7), while HEK-293 cells were used as an immortalised non-cancerous reference model for general cytotoxicity evaluation. Linear mixed-model analysis confirmed a significant incubation-time effect in all tested cancer cell lines, with IC₅₀ values generally decreasing after prolonged exposure. Statistically significant F2-F3 differences were plant-dependent. The 30% (v/v) methanol in water fraction (F2), enriched in oenothein B in C. angustifolium L., showed stronger antiproliferative activity, whereas the 60% (v/v) methanol in water fraction (F3) showed stronger activity in Quercus robur L., Juglans nigra L., Juglans regia L., and Solidago canadensis L. These findings indicate that antiproliferative activity was associated with the qualitative and quantitative composition of the selected phenolic-rich SPE fractions rather than with a single universal fraction effect. All tested fractions exhibited lower cytotoxicity toward HEK-293 cells under the applied conditions; however, claims of selectivity should be confirmed using additional normal or primary cell models. Overall, the findings clarify the role of extraction strategy, harvest stage and targeted fractionation in linking phenolic composition with biological activity.