Studies were performed for the first time on the effect of Iscador Qu and Iscador M on phototoxicity, cytotoxicity, antiproliferative activity, changes in ξ-potential of cells, membrane lipid order, actin cytoskeleton organization and migration on three breast cancer lines with different metastatic potential: MCF10A (control), MCF-7 (low metastatic) and MDA-MB231 (high metastatic) cells. The tested Iscador Qu and M did not show any phototoxicity. The antiproliferative effect of Iscador species appeared to be dose-dependent and was related to the metastatic potential of the tested cell lines. A higher selectivity index was obtained for Iscador Qu and M towards the low metastatic MCF-7 cell line compared to the high metastatic MDA-MB-231. Iscador Qu demonstrated higher selectivity for both cancer cell lines compared to Iscador M. The malignant cell lines exhibited a decrease in fibril number and thickness regardless of the type of Iscador used. The strongest effect on migration potential was observed for the low metastatic cancer cell line MCF-7 after Iscador treatment. Both Iscador species induced a slight increase in the percentage of cells in early apoptosis for the low and high metastatic cell lines, MCF-7 and MDA-MB-231, unlike control cells. Changes in the zeta potential and membrane lipid order were observed for the low metastatic MCF-7 cell line in contrast to the high metastatic MDA-MB-231 cells. The presented results reveal a higher potential of Iscador as an antitumor agent for the low metastatic cancer cell line MCF-7 compared to the high metastatic one. Iscador Qu appears to be more potent compared to Iscador M, but at this point, the exact mechanism of action is still unclear and needs further investigations.

Thienopyrimidines are structural analogs of quinazolines, and the creation of new 2-alkyl derivatives of ethyl 4-aminothienopyrimidine-6-carboxylates for the study of their anti-proliferative properties is of great pharmacological interest. Some 2-alkyl-4-amino-thieno[2,3-d]pyrimidines 2–5 were synthesized, and their cyto- and phototoxicity against BALB 3T3 cells were established by an in vitro 3T3 NRU test. The obtained results indicate that the tested compounds are not cytotoxic or phototoxic, and that they are appropriate to be studied for their anti-proliferative and anti-tumor properties. The anti-proliferative potential of the compounds was investigated on MCF-7 and MDA-MB-231 cancer cells, as well as a MCF-10A cell line (normal human mammary epithelial cells). The most toxic to MCF-7 was thienopyrimidine 3 with IC₅₀ 13.42 μg/mL (IC₅₀ 0.045 μM), followed by compound 4 (IC₅₀ 28.89 μg/mL or IC₅₀ 0.11 μM). The thienopyrimidine 4 revealed higher selectivity to MCF-7 and lower activity (IC₅₀ 367 μg/mL i.e., 1.4 μM) than compound 3 with MCF-10A cells. With respect to MDA-MB-231 cells, ester 2 manifested the highest effect with IC₅₀ 52.56 μg/mL (IC₅₀ 0.16 μM), and 2-ethyl derivative 4 revealed IC₅₀ 62.86 μg/mL (IC₅₀ 0.24 μM). It was estimated that the effect of the substances on the cell cycle progression was due to cell cycle arrest in the G2 stage for MDA-MB-231, while arrest in G1 was detected for the estrogen (ER)-positive MCF-7 cell line. The tested compound’s effects on the change of the zeta potential in the tumorigenic cells utilized in this study were determined. The calculation which we performed of the physicochemical properties and pharmacokinetic parameters influencing the biological activity suggested high intestinal absorption, as well as drug-likeness.

Nanotechnology offers alternative approaches to the discovery of anticancer drugs. Hydrophobic bioactive components can be included in the cores of amphiphilic nanocarriers, which leads to the formation of a water-dispersible product with improved bioavailability, facilitated excretion, and reduced systemic toxicity in the treated organisms. This study was aimed at the formation of polymer nanocarriers, loaded with anticancer drug precursor podophylotoxin (PPT) or PPT-containing juniper leaf extracts, seeking to study their antineoplastic activity in A-431 epidermoid carcinoma cells and HaCaT normal keratinocytes. The amphiphilic, biodegradable, and biocompatible MPEG-b-PLA diblock copolymer was self-assembled in aqueous media into nanosized particles, whose physicochemical characteristics were studied by dynamic light scattering, transmission electron microscopy, and other methods. High encapsulation efficiency was determined for the PPT component-loaded micelles. DNA fragmentation, cell cycle arrest, nuclear condensation, membrane lipid order assessment, reactive oxygen species, and apoptosis induction by the loaded nanocarriers in A-431 or HaCaT cells were analyzed by the comet assay, FACS, Hoechst DNA staining, Laurdan generalized polarization, and other methods. As a result of various cellular processes induced by the PPT component-loaded nanoparticles, effector caspase-3 and caspase-7 activation showed selectivity towards tumor cells compared to the normal cells. The newly obtained PPT-containing nanoparticles have applications as potential drugs in the prospective nanomedicine.

Oral squamous cell carcinoma (OSCC) remains a major therapeutic challenge due to aggressive progression, high recurrence, and limited selectivity of current treatments. In this study, a series of seven 4-amino-2-substituted tetrahydrobenzothieno[2,3-d]pyrimidines were evaluated for their cytotoxic, antiproliferative, and mechanistic effects against oral cancer cell lines with different metastatic potential (HSC-3 and SCC-9), alongside non-tumorigenic keratinocytes (HaCaTs). Several compounds demonstrated selective anticancer activity, with Compounds 5 and 6 showing the most favorable balance between potency and selectivity. Antiproliferative assays revealed effective inhibition of cancer cell growth, while clonogenic assays confirmed a pronounced reduction in long-term survival, particularly in highly metastatic HSC-3 cells. Mechanistic studies indicated that the anticancer effects are associated with S-phase cell cycle arrest, apoptosis induction, and profound disruption of the actin cytoskeleton. In silico ADME and drug-likeness analyses supported the lead-like properties of the most active derivatives. Overall, these findings identify thienopyrimidine derivatives as promising scaffolds for the development of targeted therapies against OSCC and warrant further optimization and in vivo evaluation.

European mistletoe extract (Iscador Qu) has been studied for decades, but it has not ceased to arouse scientific interest. The purpose was to investigate the impact of Iscador Qu on the antiproliferative potential of 11 standard chemotherapeutic agents on two breast cancer cell lines: MCF-7 low-metastatic and MDA-MB-231 high-metastatic and control cell lines (MCF-10A). MTT-dye reduction assay, FACS analysis, and PI staining were utilized. The most promising combinations acting against the MDA-MB-231 cell line were observed upon the simultaneous application of Iscador Qu (80 µg/mL) and Docetaxel, with 4-fold reduction in IC₅₀. An antagonistic effect was found under treatment with Cisplatin and Iscador Qu (1.5-fold increase in IC₅₀). The response of the low-metastatic breast cancer cell line MCF-7 to the tested combinations was different compared to the high-metastatic one. The most pronounced cytotoxic effect was found for the combination of Oxaliplatin and Iscador Qu (20 µg/mL) (5.2-fold IC₅₀ reduction). An antagonistic effect for MCF-7 line was also observed when combinations with Olaparib and Tamoxifen were applied. This in vitro study offers new combinations between Iscador Qu and standard chemotherapeutic agents that hold great promise in establishing breast cancer therapeutic protocols compared to traditional monotherapies.

Petasin, a lipophilic sesquiterpene ester isolated from Petasites hybridus, exhibits well-documented anti-inflammatory and anti-allergic activities, although its molecular mechanisms of action remain incompletely understood. Here, we investigated its direct effects on membrane organization using biomimetic large unilamellar vesicles (LUVs) modeling resting and activated mast cell plasma membranes. The models comprised phosphatidylcholines (EggPC, PAPC), sphingomyelin (SM), ganglioside GD3, and cholesterol (Chol), with phosphatidylserine (PS) additionally incorporated into the activated membrane model. Simplified liquid-disordered (L_d) and liquid-ordered (L_o) lipid systems were used to resolve phase-dependent effects. Membrane properties were assessed by Laurdan generalized polarization, DPH fluorescence anisotropy, DPH-TEMPO fluorescence quenching, di-8-ANEPPS dipole potential measurements, and dynamic light scattering (DLS). Petasin exerted phase- and composition-dependent effects on membrane organization. It increased lipid order in relatively disordered membrane environments, while producing only minor changes in highly ordered L_o membranes, revealing a clear dependence of its effects on the initial lipid phase state. In heterogeneous mast cell membrane models exhibiting L_o/L_d phase coexistence, DPH-TEMPO quenching indicated a concentration-dependent increase in the estimated size of ordered lipid nanodomains. In parallel, petasin decreased membrane dipole potential in a concentration-dependent manner, demonstrating modulation of membrane interfacial electrostatic properties. These findings indicate coordinated modulation of lipid packing, lateral membrane organization, and interfacial electrostatics, with the membrane response influenced by lipid composition. DLS measurements showed no evidence of vesicle aggregation or major alterations in vesicle size distribution. Overall, these findings identify petasin as a membrane-active modulator capable of fine-tuning lipid order, lateral membrane organization, and interfacial electrostatics in a phase- and composition-dependent manner. Given the importance of membrane organization and lipid raft dynamics in FcεRI clustering and mast cell activation, these membrane effects may represent an additional biophysical mechanism of the anti-inflammatory and anti-allergic actions of petasin. More broadly, our findings highlight membrane physicochemical organization as a relevant factor in the regulation of mast cell function and provide a basis for further investigation of membrane-mediated mechanisms in allergic and mast cell-associated inflammatory responses.