Synthesis, anticancer activity, and molecular docking of half-sandwich iron(II) cyclopentadienyl complexes with maleimide and phosphine or phosphite ligands.

In these studies, we designed and investigated the potential anticancer activity of five iron(II) cyclopentadienyl complexes bearing different phosphine and phosphite ligands. All complexes were characterized with spectroscopic analysis viz. NMR, FT-IR, ESI-MS, UV-Vis, fluorescence, XRD (for four complexes) and elemental analyses. For biological studies, we used three types of cells-normal peripheral blood mononuclear (PBM) cells, leukemic HL-60 cells and non-small-cell lung cancer A549 cells. We evaluated cell viability and DNA damage after cell incubation with these complexes. We observed that all iron(II) complexes were more cytotoxic for HL-60 cells than for A549 cells. The complex CpFe(CO)(P(OPh)3)(η1-N-maleimidato) 3b was the most cytotoxic with IC50 = 9.09 µM in HL-60 cells, IC50 = 19.16 µM in A549 and IC50 = 5.80 µM in PBM cells. The complex CpFe(CO)(P(Fu)3)(η1-N-maleimidato) 2b was cytotoxic only for both cancer cell lines, with IC50 = 10.03 µM in HL-60 cells and IC50 = 73.54 µM in A549 cells. We also found the genotoxic potential of the complex 2b in both types of cancer cells. However, the complex CpFe(CO)2(η1-N-maleimidato) 1 which we studied previously, was much more genotoxic than complex 2b, especially for A549 cells. The plasmid relaxation assay showed that iron(II) complexes do not induce strand breaks in fully paired ds-DNA. The DNA titration experiment showed no intercalation of complex 2b into DNA. Molecular docking revealed however that complexes CpFe(CO)(PPh3) (η1-N-maleimidato) 2a, 2b, 3b and CpFe(CO)(P(OiPr)3)(η1-N-maleimidato) 3c have the greatest potential to bind to mismatched DNA. Our studies demonstrated that the iron(II) complex 1 and 2b are the most interesting compounds in terms of selective cytotoxic action against cancer cells. However, the cellular mechanism of their anticancer activity requires further research.

Piano-stool ruthenium(II) complexes with maleimide and phosphine or phosphite ligands: synthesis and activity against normal and cancer cells.

In these studies, we designed and investigated cyto- and genotoxic potential of five ruthenium cyclopentadienyl complexes bearing different phosphine and phosphite ligands. All of the complexes were characterized with spectroscopic analysis (NMR, FT-IR, ESI-MS, UV-vis, fluorescence and XRD (for two compounds)). For biological studies, we used three types of cells - normal peripheral blood mononuclear (PBM) cells, leukemic HL-60 cells and doxorubicin-resistance HL-60 cells (HL-60/DR). We compared the results obtained with those obtained for the complex with maleimide ligand CpRu(CO)2(η1-N-maleimidato) 1, which we had previously reported. We observed that the complexes CpRu(CO)(PPh3)(η1-N-maleimidato) 2a and CpRu(CO)(P(OEt)3)(η1-N-maleimidato) 3a were the most cytotoxic for HL-60 cells and non-cytotoxic for normal PBM cells. However, complex 1 was more cytotoxic for HL-60 cells than complexes 2a and 3a (IC50 = 6.39 µM vs. IC50 = 21.48 µM and IC50 = 12.25 µM, respectively). The complex CpRu(CO)(P(OPh)3)(η1-N-maleimidato) 3b is the most cytotoxic for HL-60/DR cells (IC50 = 104.35 µM). We found the genotoxic potential of complexes 2a and 3a only in HL-60 cells. These complexes also induced apoptosis in HL-60 cells. Docking studies showed that complexes 2a and CpRu(CO)(P(Fu)3)(η1-N-maleimidato) 2b have a small ability to degrade DNA, but they may cause a defect in DNA damage repair mechanisms leading to cell death. This hypothesis is corroborated with the results obtained in the plasmid relaxation assay in which ruthenium complexes bearing phosphine and phosphite ligands induce DNA breaks.

Antioxidant Activity of Ruthenium Cyclopentadienyl Complexes Bearing Succinimidato and Phthalimidato Ligands.

In these studies, we investigated the antioxidant activity of three ruthenium cyclopentadienyl complexes bearing different imidato ligands: (η5-cyclopentadienyl)Ru(CO)2-N-methoxysuccinimidato (1), (η5-cyclopentadienyl)Ru(CO)2-N-ethoxysuccinimidato (2), and (η5-cyclopentadienyl)Ru(CO)2-N-phthalimidato (3). We studied the effects of ruthenium complexes 1-3 at a low concentration of 50 µM on the viability and the cell cycle of peripheral blood mononuclear cells (PBMCs) and HL-60 leukemic cells exposed to oxidative stress induced by hydrogen peroxide (H2O2). Moreover, we examined the influence of these complexes on DNA oxidative damage, the level of reactive oxygen species (ROS), and superoxide dismutase (SOD) activity. We have observed that ruthenium complexes 1-3 increase the viability of both normal and cancer cells decreased by H2O2 and also alter the HL-60 cell cycle arrested by H2O2 in the sub-G1 phase. In addition, we have shown that ruthenium complexes reduce the levels of ROS and oxidative DNA damage in both cell types. They also restore SOD activity reduced by H2O2. Our results indicate that ruthenium complexes 1-3 bearing succinimidato and phthalimidato ligands have antioxidant activity without cytotoxic effect at low concentrations. For this reason, the ruthenium complexes studied by us should be considered interesting molecules with clinical potential that require further detailed research.

Effect of Kaempferol and Its Glycoside Derivatives on Antioxidant Status of HL-60 Cells Treated with Etoposide.

Kaempferol is a well-known antioxidant found in many plants and plant-based foods. In plants, kaempferol is present mainly in the form of glycoside derivatives. In this work, we focused on determining the effect of kaempferol and its glycoside derivatives on the expression level of genes related to the reduction of oxidative stress-NFE2L2, NQO1, SOD1, SOD2, and HO-1; the enzymatic activity of superoxide dismutases; and the level of glutathione. We used HL-60 acute promyelocytic leukemia cells, which were incubated with the anticancer drug etoposide and kaempferol or one of its three glycoside derivatives isolated from the aerial parts of Lens culinaris Medik.-kaempferol 3-O-[(6-O-E-caffeoyl)-ß-d-glucopyranosyl-(1→2)]-ß-d-galactopyranoside-7-O-ß-d-glucuropyranoside (P2), kaempferol 3-O-[(6-O-E-p-coumaroyl)-ß-d-glucopyranosyl-(1→2)]-ß-d-galactopyranoside-7-O-ß-d-glucuropyranoside (P5), and kaempferol 3-O-[(6-O-E-feruloyl)-ß-d-glucopyranosyl-(1→2)]-ß-d-galactopyranoside-7-O-ß-d-glucuropyranoside (P7). We showed that none of the tested compounds affected NFE2L2 gene expression. Co-incubation with etoposide (1 µM) and kaempferol (10 and 50 µg/mL) leads to an increase in the expression of the HO-1 (9.49 and 9.33-fold at 10 µg/mL and 50 µg/mL, respectively), SOD1 (1.68-fold at 10 µg/mL), SOD2 (1.72-fold at 10-50 µg/mL), and NQO1 (1.84-fold at 50 µg/mL) genes in comparison to cells treated only with etoposide. The effect of kaempferol derivatives on gene expression differs depending on the derivative. All tested polyphenols increased the SOD activity in cells co-incubated with etoposide. We observed that the co-incubation of HL-60 cells with etoposide and kaempferol or derivative P7 increases the level of total glutathione in these cells. Taken together, our observations suggest that the antioxidant activity of kaempferol is related to the activation of antioxidant genes and proteins. Moreover, we observed that glycoside derivatives can have a different effect on the antioxidant cellular systems than kaempferol.

Multifunctional compounds in the extract from mature seeds of Vicia faba var. minor: Phytochemical profiling, antioxidant activity and cellular safety in human selected blood cells in in vitro trials.

BACKGROUND: The field bean (Vicia faba) is a valuable fodder plant of the Fabaceae family, grown as a main crop for its seed yield. Its phytochemical profile is characterized by the presence of a range of compounds with various biological activities. PURPOSE: The present study investigates the phytochemical profile of the extract from mature seeds of Vicia faba var. minor and examines its impact on preventing oxidative damage to various lipids, protein and DNA molecules in vitro. METHODS: Human plasma was treated with H2O2/Fe (an OH. donor) to induce oxidative damage to lipids and proteins, and the plant extract was then added. As oxidative stress may influence the biological activity of plasma, e.g. coagulation, and influence cardiovascular disease, the study also examined the effect of the plant extract on coagulation and monoamine oxidase activity (MAO, EC 1.4.3.4). RESULTS: The tested extract exerted a protective effect on plasma lipids and proteins treated with H2O2/Fe. However, while it appears to effectively protect the DNA in peripheral blood mononuclear cells from oxidative damage, it did not induce changes in the coagulation process, and significantly reduced MAO activity when applied at 1, 5, and 10 µg/mL. It is possible that the observed antioxidant potential may be due to the complex chemical composition of the extract: the phytochemical profile demonstrated a range of phenolic compounds, including catechins. CONCLUSION: Our findings indicate that extract from mature seeds of V. faba var. minor may be a promising source of antioxidants in multiple applications, including diseases associated with oxidative stress; however, more studies based on in vitro and in vivo models are needed to determine its biological properties.

Kaempferol and Its Glycoside Derivatives as Modulators of Etoposide Activity in HL-60 Cells.

Kaempferol is a polyphenol found in a variety of plants. Kaempferol exerts antitumor properties by affecting proliferation and apoptosis of cancer cells. We investigated whether kaempferol and its glycoside derivatives-kaempferol 3-O-[(6-O-E-caffeoyl)-ß-D-glucopyranosyl-(1→2)]-ß-D-galactopyranoside-7-O-ß-D-glucuropyranoside (P2), kaempferol 3-O-[(6-O-E-p-coumaroyl)-ß-D-glucopyranosyl-(1→2)]-ß-D-galactopyranoside-7-O-ß-D-glucuropyranoside (P5) and kaempferol 3-O-[(6-O-E-feruloyl)-ß-D-glucopyranosyl-(1→2)]-ß-D-galactopyranoside-7-O-ß-D-glucuropyranoside (P7), isolated from aerial parts of Lens culinaris Medik.-affect the antitumor activity of etoposide in human promyelocytic leukemia (HL-60) cells. We analyzed the effect of kaempferol and its derivatives on cytotoxicity, DNA damage, apoptosis, cell cycle progression and free radicals induced by etoposide. We demonstrated that kaempferol increases the sensitivity of HL-60 cells to etoposide but does not affect apoptosis induced by this drug. Kaempferol also reduces the level of free radicals generated by etoposide. Unlike kaempferol, some of its derivatives reduce the apoptosis of HL-60 cells (P2 and P7) and increase the level of free radicals (P2 and P5) induced by etoposide. Our results indicate that kaempferol and its glycoside derivatives can modulate the activity of etoposide in HL-60 cells and affect its antitumor efficacy in this way. Kaempferol derivatives may have the opposite effect on the action of etoposide in HL-60 cells compared to kaempferol.

Multidirectional effects of saponin fraction isolated from the leaves of sea buckthorn Elaeagnus rhamnoides (L.) A. Nelson.

Many studies show that saponins isolated from various plants have a cytotoxic effect on cancer cells inducing apoptosis and autophagy. On the other hand, saponins also exhibit a number of beneficial properties, such as antioxidant properties. Thus, saponins can be considered both in terms of their therapeutic and protective effects during anticancer treatment. In this study, we investigated the effect of the saponin fraction isolated from sea buckthorn (Elaeagnus rhamnoides (L.) A. Nelson) leaves on the viability of HL-60 cancer cells using resazurin assay and its ability to induction of apoptosis with Annexin V-FITC and propidium iodide (PI) double staining. Moreover, we studied its effect on the oxidative stress induced by H2O2, and anti-platelet and anticoagulant potential in whole blood using T-TAS, a microchip-based flow chamber system. We observed that the saponin fraction significantly decreased the viability of HL-60 cells at the concentration above 50 µg/mL and induced apoptosis at the concentration of 100 µg/mL. Moreover, we observed that saponin fraction used at lower concentrations, such as 0.5 and 1 µg/mL, stimulated HL-60 cells and increased their viability. The saponin fraction also decreased the level of free radicals and reduced oxidative DNA damage measured by the comet assay. However, at high concentration of oxidant H2O2 equal 5 mM, we noticed that the saponin fraction at 50 µg/mL increased the level of free radicals in HL-60 cells. We also demonstrated anticoagulant potential of the saponin fraction at the concentration of 50 µg/mL. Our results indicate that the saponin fraction obtained from sea buckthorn leaves can show both chemotherapeutic and chemoprotective potential.

LC/MS Analysis of Saponin Fraction from the Leaves of Elaeagnus rhamnoides (L.) A. Nelson and Its Biological Properties in Different In Vitro Models.

This study focuses on saponin fraction from sea buckthorn (Elaeagnus rhamnoides (L.) A. Nelson) leaves. It has known that for example teas from sea buckthorn leaves have anti-obesity properties. The objective of our present experiments was to investigate both the chemical composition of saponin fraction, as well as their biological properties in different in vitro models (using human plasma, blood platelets, and peripheral blood mononuclear cells (PBMCs)). We observed that saponin fraction reduces plasma lipid peroxidation and protein carbonylation induced by H2O2/Fe. This fraction also decreased DNA oxidative damage induced by H2O2 in PBMCs. Regarding the cytotoxicity of saponin fraction (0.5-50 µg/mL) none was found to cause lysis of blood platelets, and PBMCs. Our results, for the first time indicate that saponin fraction from sea buckthorn leaves may be a new promising source of compounds for prophylaxis and treatment of diseases associated with oxidative stress.

DNA damage and antioxidant properties of CORM-2 in normal and cancer cells.

In this study, we compared the effect of tricarbonyldichlororuthenium (II) dimer (CORM-2) and its CO-depleted molecule (iCORM-2) on human peripheral blood mononuclear cells (PBMCs) and human promyelocytic leukemia HL-60 cells. We determined cell viability, DNA damage and DNA repair kinetics. We also studied the effect of both compounds on DNA oxidative damage, free radical level and HO-1 gene expression. We showed that at low concentrations both CORM-2 and iCORM-2 stimulate PBMCs viability. After 24-h incubation, CORM-2 and iCORM-2, at the concentration of 100 µM, reduce the viability of both PBMCs and HL-60 cells. We also demonstrated that CORM-2 and iCORM-2, in the 0.01-100 µM concentration range, cause DNA damage such as strand breaks and alkaline labile sites. DNA damage was repaired efficiently only in HL-60 cells. CORM-2 significantly reduces oxidative stress induced by 1 mM H2O2 in normal and cancer cells. On the contrary, iCORM-2 in HL-60 cells increases the level of free radicals in the presence of 1 and 5 mM H2O2. We also revealed that both CORM-2 and iCORM-2 induce HO-1 gene expression. However, CORM-2 induces this gene to a greater extent than iCORM-2, especially in HL-60 cells at 100 µM. Finally, we showed that CORM-2 and iCORM-2 reduce H2O2-induced DNA oxidative damage. Furthermore, CORM-2 proved to be a compound with stronger antioxidant properties than iCORM-2. Our results suggest that both active CORM-2 and inactive iCORM-2 exert biological effects such as cyto- and genotoxicity, antioxidant properties and the ability to induce the HO-1 gene. The released CO as well as iCORM-2 can be responsible for these effects.

Photoactive CO-releasing complexes containing iron - genotoxicity and ability in HO-1 gene induction in HL-60 cells.

This paper presents the results of research on the biological properties of two photoactive CO-releasing molecules containing iron, i.e. (η5-C5H5)Fe(CO)2(η1-N-maleimidato) (complex A) and (η5-C5H5)Fe(CO)2(η1-N-succinimidato) (complex B). We studied their cytotoxicity, genotoxicity and the ability of inducing the HO-1 gene in HL-60 cells. We also investigated the kinetics of DNA damage repair induced by complexes A and B. We demonstrated that complex B was not toxic to HL-60 cells in high doses (above 100 µM). The ability to induce DNA damage was higher for complex A. Importantly, there was no difference in irradiated and non-irradiated cells for both complexes. DNA damage induced by complex B was repaired efficiently, while the repair of DNA damage induced by complex A was disturbed. Complex B had a minor effect on HO-1 gene expression (less than 2-fold induction), while complex A had induced HO-1 gene expression to a great extent (over 17-fold for 10 µM) - similarly in irradiated and non-irradiated HL-60 cells. The results of our research indicate that the ability of both complexes to damage DNA and to upregulate HO-1 gene expression is not related to the release of CO. Further research is needed to test whether these compounds can be considered as potential CO carriers in humans.

Kaempferol derivatives isolated from Lens culinaris Medik. reduce DNA damage induced by etoposide in peripheral blood mononuclear cells.

Bioactive compounds isolated from plants are considered to be attractive candidates for cancer therapy. In this study, we examined the effect of kaempferol, its derivatives, the polyphenol fraction (PF) and an extract (EX) isolated from the aerial parts of Lens culinaris Medik. on DNA damage induced by etoposide in human cells. We also studied the effect of these compounds and their combinations on cell viability. The studies were conducted on HL-60 cells and human peripheral blood mononuclear cells (PBMCs). We used the comet assay in the alkaline version to evaluate DNA damage. To examine cell viability we applied the trypan blue exclusion assay. We demonstrated that kaempferol glycoside derivatives isolated from the aerial parts of Lens culinaris Medik. reduce DNA damage induced by etoposide in PBMCs, but do not have an impact on DNA damage in HL-60 cells. We also showed that kaempferol induces DNA damage in HL-60 cells and leads to an increase of DNA damage provoked by etoposide. Our data suggest that kaempferol derivatives can be further explored as a potential agent protecting normal cells against DNA damage induced by etoposide. Moreover, kaempferol's ability to induce DNA damage in cancer cells and to increase DNA damage caused by etoposide may be useful in designing and improving anticancer therapies.