This study presents a novel strategy for studying the microstructure of PLGA-PEG-PLGA triblock copolymers synthesized via the ROP mechanism using various organic catalysts. The use of model copolymers (PLG-PEG-PLG, PLA-PEG-PLA) and multidimensional NMR spectroscopy (HSQC, HMBC, DOSY) enabled a more comprehensive characterization of the structure of PLGA-PEG-PLGA copolymers. The new method was verified by comparing the average molecular weights with the reference method-gel permeation chromatography. NMR analysis demonstrated a close correlation between the type of catalyst used, the monomer sequence arrangement, and the average molecular weights. The Zn(acac)₂ and Fe(acac)₃ catalysts demonstrated similar activity to the commonly used Sn(Oct)₂, making them potential substitutes in the synthesis of PLGA-PEG-PLGA copolymers. The proposed methodology provides detailed insight into copolymer microstructure, enabling more precise design of copolymers, which is essential for optimizing drug delivery systems.

BACKGROUND:In this study, we aimed to compare metabolomic profiles, biodistribution, and detoxification patterns of the novel SN-38 derivative NMe with irinotecan (IR), and to identify NMe-specific metabolites to evaluate its preclinical pharmacokinetic advantages. METHODS:In vivo ADME studies were conducted for NMe, a 9-aminomethyl SN-38 derivative, and IR following a single intraperitoneal dose of 40 mg/kg in mice. Additionally, ADMET properties were predicted using ADMETlab and SwissADME tools for comparison. Levels of NMe and irinotecan absorbed into plasma, distributed to tissues, and metabolized were monitored in liver, lung, spleen, kidney, and stool samples at 15, 30, and 60 min post-administration. Tissue extracts were analysed using high-performance liquid chromatography (HPLC), liquid chromatography-electrospray ionization quadrupole time-of-flight-tandem mass spectrometry (LC-ESI-QTOF-MS), and nuclear magnetic resonance (NMR) techniques after lyophilization and reconstitution. We compared the metabolomic profiles of irinotecan and NMe. RESULTS:We identified and confirmed NMe-specific metabolites, including 9-CH2-S-cysteine conjugate, 9-CH2OH, and NMe-formyl. Notably, novel irinotecan metabolites (IR-OH and IR-ΔE) were detected in small amounts in kidney samples. In some cases, two literature-known photodegradation products of irinotecan were present. NMe was found to quickly metabolize with different distribution to tissues, significantly greater to kidney and liver. Two SN-38 glucuronides, SN-38G(α) and SN-38G(β), were detected corresponding to α- and β-anomers. Where it was possible, NMe, IR and SN-38 were quantified using external calibration curves. In IR group, controlled and prolonged release of SN-38 was confirmed in all samples, yet SN-38G was observed in minority only in plasma, kidney, or lungs. In NMe groups, great relative amounts of SN-38 and SN-38G were detected. Greater content of SN-38G in NMe group than in irinotecan is expected to contribute to modulation and alleviation of some side effects in irinotecan-involved therapies, such as gastrointestinal toxicities (GIT). CONCLUSIONS:NMe shows a distinct metabolic profile characterized by rapid biotransformation, higher systemic glucuronidation of SN-38, and formation of unique metabolites, suggesting a potentially wider therapeutic window and reduced toxicity compared with IR.

Four new azole-platinum(II) complexes with the general formulas cis-[PtCl2(L1)2] (1), cis-[PtCl2(L2)2] (2), trans-[PtCl2(L1)(DMSO)] (3), and trans-[PtCl2(L2)(DMSO)] (4), where L1 is 1-(benzofuran-2-yl)-2-(1H-1,2,4-triazol-1-yl)ethenone, L2 is (benzofuran-2-yl)-2-(1H-imidazol-1-yl)ethenone, and DMSO is dimethyl sulfoxide, were synthesized and fully characterized. The compositions of the coordination spheres were established using spectroscopic methods (1H, 13C, 15N, 195Pt NMR; IR; X-ray). Complexes (1) and (2) adopted cis geometries, featuring two triazole ligands L1 in (1) or two imidazole ligands L2 in (2), each coordinated through the nitrogen donor atom N4″, along with two chloride ions. In contrast, complexes (3) and (4) exhibited trans configurations and contained one azole ligand (L1 or L2), each coordinated via a nitrogen donor N4″ atom, an S-donor DMSO molecule, and two chloride ions. All complexes displayed moderate lipophilicity (logP = 0.92-1.12) and markedly reduced reactivity toward glutathione compared with cisplatin, reflecting the steric shielding provided by the azole ligands. Despite these favorable physicochemical features, only complex (1) demonstrated notable intrinsic in vitro cytotoxicity. It showed activity against a lung cancer cell line (A549) and four bladder cancer cell lines (T24, HT1376, 5637, and HB-CLS-1), with IC50 values ranging from 5.00 to 8.50 µM. Comparable toxicity was observed toward normal SV-HUC-1 urothelial cells (IC50 = 8.54 µM). Notably, complex (1) induced only minor alterations in the cell-cycle profile, suggesting a mechanism of action distinct from those of classical DNA-targeting platinum drugs. To improve its therapeutic performance, complex (1) was encapsulated in polymeric micelles formed by PEO-PPO-PEO triblock copolymers. This nanoformulation resulted in a striking increase in anticancer activity, yielding submicromolar IC50 values (0.13-0.94 µM). The corresponding toxicity toward normal SV-HUC-1 cells ranged from IC50 = 0.17 to 0.75 µM. The substantial increase in potency suggests that micellar delivery enhances intracellular accumulation while protecting the complex from premature deactivation. These results suggest that triazole-based platinum(II) complexes, particularly when combined with polymeric nanocarriers, may represent a promising system for further investigation in the development of platinum-based chemotherapeutic drugs.

To directly probe the role of the metal centre in cyclometalated anticancer agents, we developed a new series of heteroleptic Rh(III) complexes as rhodium congeners of our previously reported Ir(III) complexes based on the same C,N-donor ligand framework. Such a comparative insight will allow us to take a broader look at the mechanism of action of the complexes under investigation as potential chemotherapeutic agents. Three novel cyclometalated Rh(III) compounds containing 3,5-dimethyl-1-phenyl-1H-pyrazole (Hdmppz) and the N,N-donor ligands 2-di(pyridyl)ketone (Py2CO), 2,2-biimidazole (H2biim), and 2-(2-pyridyl)benzimidazole (PyBIm) were synthesized: [Rh(dmppz)2(Py2CO)]PF6 (1), [Rh(dmppz)2(H2biim)]PF6·H2O (2), and [Rh(dmppz)2(PyBIm)]PF6·H2O (3). This matched Rh(III)/Ir(III) design enables a rare head-to-head comparison in which the ligand environment is retained and the central ion is the key variable. The complexes were comprehensively characterised by SC-X-ray diffraction, FTIR, elemental analysis, ESI-MS, UV-Vis, PL, and 1H, 13C and 15N NMR spectroscopy. The biological evaluation showed that the new Rh(III) complexes display pronounced antiproliferative activity against MCF-7, K-562 and CCRF-CEM cancer cell lines, with IC50 values determined together with those for the normal MRC-5 cell line. To elucidate their mode of action, interactions with biologically relevant targets, namely DNA and HSA, were studied by UV-Vis and CD spectroscopy as well as molecular docking. Their redox reactivity toward NADH and GSH was also examined by UV-Vis. In addition, intracellular ROS generation, cell-cycle perturbation, apoptosis induction and confocal microscopy imaging were investigated. Most importantly, comparison with the previously reported Ir(III) analogues demonstrates that replacing Ir(III) with Rh(III) within the same cyclometalated scaffold significantly affects the biological profile of the complexes. The results indicate that DNA interaction is largely governed by the ligand framework, whereas modulation of cellular redox processes depends more strongly on the nature of the metal centre. These findings identify the new Rh(III) complexes as promising multitarget cytotoxic agents and establish direct Rh(III)/Ir(III) comparison as a useful strategy for the rational design of new metallodrugs.

This study presents a methodology for developing a cyclodextrin-based delivery system for ceftobiprole, a poorly water-soluble and amphoteric drug, chemically stable in acidic conditions. Ceftobiprole is a broad-spectrum cephalosporin antibiotic administered clinically as its water-soluble prodrug, ceftobiprole medocaril, due to limited aqueous solubility of the parent compound. Solubility enhancement was achieved through complexation with anionic sulfobutylether-β-cyclodextrin (SBE-β-CD). At a pH below 3, ceftobiprole is protonated and cationic, which facilitates electrostatic interactions with the anionic cyclodextrin. An optimised high-performance liquid chromatography (HPLC) method was used to assess solubility, the impurity profile, and long-term chemical stability. X-ray powder diffraction (XRPD) confirmed the amorphous nature of the system and the absence of recrystallization. Nuclear magnetic resonance (NMR) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy supported the formation of a host–guest complex. The freeze-dried system prepared from 0.1 M formic acid solution contained negligible residual acid due to nearly complete sublimation. The most promising formulation was a ternary system of ceftobiprole, maleic acid, and SBE-β-CD (1:25:4 molar ratio), showing ~300-fold solubility improvement, low levels of degradation products, and stability after eight months at −20 °C. After pH adjustment to a parenterally acceptable level, the formulation demonstrated solubility and a pH comparable to the marketed drug product.

The main goal of our research was to examine (1S,4R,5R)-4-(4-phenyl-1H-1,2,3-triazol-1-yl)-2-((S)-1-phenylethyl)-2-azabicyclo[3.2.1]octane (L) and its complex-forming abilities with platinum(II) ions. Herein, we present three new square planar platinum(II) complexes of the general formulas trans-[PtCl2L2] (1), cis-[PtCl2(DMSO)(L)] (2) and [Pt(DMSO)(L)(mal)] (3), where DMSO: dimethyl sulfoxide; mal: malonate. Based on the experimental spectroscopic results (1H, 13C, 15N, 195Pt NMR, IR, X-ray analyses) and density functional theoretical calculation (DFT), a square planar geometry was proposed with one or two monodentate bound N3' heterocyclic ligands (L). Surrounding the central atom, there are monodentate chloride (1) and (2) or chelated O,O-donor malonate ligands (3). The coordination spheres in (2) and (3) were completed by the S-donor monodentate dimethyl sulfoxide molecule. Theoretical investigations into the heterocyclic ligand coordination site and geometry around the central ion were performed by DFT calculation, and the results were consistent with the experimental data. The DFT calculations elucidate the thermodynamic preferences for cis versus trans arrangements of the ligands in the isolated platinum(II) complexes (1) and (2), suggesting that the trans arrangement of chloride anions observed in the crystals of (2a) probably results from the crystal packing. The obtained platinum(II) complexes were examined with regard to their therapeutic anticancer potential. In comparison to cisplatin, lipophilic complexes (1) and (3) exhibit lower affinity toward glutathione. According to observations, (1) presents the most satisfactory in vitro activity with the mechanism of its cytotoxic effect on cancer cells different from that of cisplatin.

In this paper, we present the synthesis of four new complexes: the dimeric precursor [Ir(dmppz)(2)(mu-Cl)](2) (1) (Hdmppz - 3,5-dimethyl-1-phenyl-1H-pyrazole) and heteroleptic bis-cyclometalated complexes: [Ir(dmppz)(2)(Py2CO)]PF61/2 CH2Cl2 (2), [Ir(dmppz)(2)(H(2)biim)]PF6H2O (3), and [Ir(dmppz)(2)(PyBIm)]PF6 (4), with auxiliary N,N-donor ligands: 2-di(pyridyl)ketone (Py2CO), 2,2 '-biimidazole (H(2)biim) and 2-(2 '-pyridyl)benzimidazole (PyBIm). In the obtained complexes, SC-X-ray analysis revealed that Ir(III) has an octahedral coordination sphere with chromophores of the type {IrN2C2Cl2} (1) or {IrN4C2} (2-4). The complexes obtained, which have been fully characterised by physicochemical methods (CHN, TG, FTIR, UV-Vis, PL and H-1, C-13, N-15 NMR), were used to continue our studies on the factors influencing the cytotoxic properties of potential chemotherapeutic agents (in vitro). To this end, the following studies are presented: (i) comparative analysis of the effects on the biological properties of N,N-donor ligands and C,N-donor ligands in the studied complexes, (ii) studies of the interactions of the compounds with the selected molecular target: DNA and BSA (UV-Vis, CD and PL methods), (iii) and the reactivity towards redox molecules: GSH, NADH (UV-Vis and/or ESI-MS methods), (iv) cytotoxic activity (IC50) of potential chemotherapeutics against MCF-7, K-562 and CCRF-CEM cell lines.

Organometallic half-sandwich complexes [(η5-Cp)IrCl(L)]PF6 (1) and [(η5-Cp)RhCl(L)]PF6 (2) were prepared using pentamethylcyclopentadienyl chloride dimers of iridium(III) or rhodium(III) with the 4-amino-N-(2,2'-bipyridin-5-yl)benzenesulfonamide ligand (L) and ammonium hexafluorophosphate. The crystal structures of L, 1, and 2 were analyzed in detail. The coordination reactions of the ligand with the central ions were confirmed using various spectroscopic techniques. Additionally, the interactions between sulfaligand, Ir(III), and Rh(III) complexes with carbonic anhydrase (CA), human serum albumin (HSA), and CT-DNA were investigated. The iridium(III) complex (1) did not show any antiproliferative properties against four different cancer cell lines, i.e., nonsmall cell lung cancer A549, colon cancer HCT-116, breast cancer MCF7, lymphoblastic leukemia Nalm-6, and a nonmalignant human embryonic kidney cell line HEK293, due to high binding affinity to GSH. The sulfonamide ligand (L) and rhodium(III) complex (2) were further studied. L showed competitive inhibition toward CA, while complexes 1 and 2, uncompetitive. All compounds interacted with HSA, causing a conformational change in the protein's α-helical structure, suggesting the induction of a more open conformation in HSA, reducing its biological activity. Both L and 2 were found to induce cell death through a caspase-dependent pathway. These findings position L and 2 as potential starting compounds for pharmaceutical, therapeutic, or medicinal research.

Three new ruthenium(II) complexes with biphenyl (bip), and disubstituted 1,2,4-triazolo[1,5-a]pyrimidine (dstp) of the general formula [(eta 6-bip)Ru(dstp)Cl2], where dstp - dmtp - 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine for (1), dptp - 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine for (2), or ibmtp - 7-isobutyl-5-methyl1,2,4-triazolo[1,5-a]pyrimidine for (3) have been synthesized and fully characterized by an elemental analysis and spectroscopic methods (1H, 13C, 15N NMR; IR; X-ray). The crystal sructures of two complexes have been solved. To determine the therapeutic potential of the newly synthesized compounds, examinations of their biological properties such as lipophilicity and in vitro cytotoxicity towards T47D (breast cancer), A549 (non-small cell lung cancer), LoVo (colon cancer), and one healthy cell line mouse fibroblasts - BALB3T3 were preformed. The results show that all the tested ruthenium(II) complexes present higher lipophilicity (logP = 0.79 - 1.43) than Cisplatin (-2.31). From among all the newly obtained complexes, (2) (IC50 = 25 - 29 mu M) exhibits the highest cytotoxicity.Based on the own results and literature data we reported earlier, it can be confirmed that the in vitro cytotoxicity of ruthenium(II) complexes increases with an increase in the size of the arene ligand.

The new 5-substituted SN-38 derivatives, 5(R)-(N-pyrrolidinyl)methyl-7-ethyl-10-hydroxycamptothecin (1) and its diastereomer 5(S) (2), were investigated using a combination of nuclear magnetic resonance (NMR) spectroscopy and molecular modeling methods. The chemical stability, configuration stability, and propensity to aggregate as a function of concentration were determined using 1H NMR. The calculated self-association constants (Ka) were found to be 6.4 mM-1 and 2.9 mM-1 for 1 and 2, respectively. The NMR experiments were performed to elucidate the interaction of each diastereomer with a nicked decamer duplex, referred to as 3. The calculated binding constants were determined to be 76 mM-1 and 150 mM-1 for the 1-3 and 2-3 complexes, respectively. NMR studies revealed that the interaction between 1 or 2 and the nicked decamer duplex occurred at the site of the DNA strand break. To complement these findings, molecular modeling methods and calculation protocols were employed to establish the interaction mode and binding constants and to generate molecular models of the DNA/ligand complexes.

Mononuclear platinum(II) complexes with 5,7-methyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) of the general formula cis-[Pt(X)2(dmtp)2], where X -acetate (1), trichloroacetate (2), trifluoroacetate (3), nitrate (4) have been synthesized and characterized by multinuclear magnetic resonance (1H, 13C, 15N, 195Pt) and infrared spectroscopy methods. Spectroscopic parameters indicated the presence of the PtO2N2 chromophore system with two monodentate N(3)-bonded 5,7-methyl-1,2,4-triazolo[1,5-a]pyrimidines, and two monodentate O-donor li-gands (carboxylate or nitrate).A cytotoxicity assay of hydrophilic platinum(II) complexes (1-4) against three human tumour cell lines A549 (non-small cell lung carcinoma), T47D (breast cancer), HT-29 (colon adenocarcinoma), and normal murine embryonic fibroblast cells (BALB/3T3) was performed.Considering the cytotoxic parameters of the studied complexes, the best in vitro results against the human breast tumour cells (T47D) were found for cis-[Pt(OOCCCl3)2(dmtp)2] although all the tested complexes (except complex (4)) exhibited moderate in vitro activity.

Dietary supplements containing vitamin K2 are often used to prevent osteoporosis, vascular calcification and coronary heart disease. It has been shown that some of these products contain a mixture of menaquinone-7 geometric isomers. Since the geometric shape may influence biological activity, there was a need for a semipreparative method to isolate single compounds for further studies. Here, we present an argentation chromatographic method for the separation of menaquinone-7 isomers and an nuclear magnetic resonance (NMR) methodology for the configuration assignment of isoprenoid side chain. The DFT calculations were performed to determine more energetically favorable complexes between the cis or trans menaquinone-7 isomers and the silver cation. Seventeen components were resolved, and fractions were collected and subjected to NMR study. Structures and chemical shifts for thirteen new compounds were assigned, and the identity of three known compounds was confirmed.

The synthesis and characterisation of new anionic iridium(II) complexes (NH4)(2)[IrCl4(kappa N-2,N'-H(2)biim)](2) center dot 5H(2)O (1) and ((CH3)(2)NH2)[IrCl4(kappa N-2,N'-PyBIm)] center dot H2O (2) are presented in this article. Spectroscopic methods (H-1, C-13 and N-15 NMR, FTIR, UV-Vis) were used to characterize these new complexes. Solid-state structural analysis (SC-XRD) of complexes 1 and 2 shows a slightly distorted octahedral geometry of Ir(III) ions, which is constructed by one chelating kappa 2N,N'-2,2'-biimidazole (H2biim (1)) or 2-(2'-pyridyl)benzimidazole (PyBIm (2)) and four chloride ions. In the crystal structures, the presence of organic ligands containing NH groups favours the formation of strong hydrogen bonds (XH center dot center dot center dot Cl (X = O, N, C)), which have significant impact on the crystal structure forming 2D (1) and 3D (2) systems during the self-assembly process. Additionally, preliminary studies of the biological activity of the obtained complexes were performed. Considering the above properties, the observed stronger binding affinity of complex 1 to DNA and HSA can be interpreted in terms of changes in the number of hydrogen bonds that are potentially formed with the target molecule. Furthermore, higher reactivity towards NADH and the lower reactivity towards GSH were observed for complex 2. Both complexes showed moderate cytotoxicity against selected cancer cell lines (LoVo, MV-4-11, MCF-7) and did not show toxicity towards normal cells (BALB/3T3). The cytotoxicity of 2 may be compromised by a weaker interaction with DNA, HSA or GSH and a stronger reactivity towards NADH.

The platinum(II) complexes of general formula [PtCl2(dstp)(S-donor)] were dstp 5,7-dimethyl-1,2,4-triazolo[1,5-a]-pyrimidine (dmtp), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp), 5-methyl-7-isobutyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) or 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp), whereas S-tetrahydrothio-phene-1-oxide (TMSO) or diphenyl sulfoxide (DPSO) were synthesized in a one-pot reaction. Here, we present experimental data (1H, 13C, 15N, 195Pt NMR, IR, X-ray) combined with density functional theory (DFT) computations to support and characterize structure–spectra relationships and determine the geometry of dichloride platinum(II) complexes with selected triazolopyrimidines and sulfoxides. Based on the experimental and theoretical data, factors affecting the stability of platinum(II) complexes have been determined.

Three sawhorse-type ruthenium(I) complexes containing purine analogs such as triazolopyrimidines of the general formula [Ru2(CO)4(μ-OOCCH3)2(L)2], where L is 1,2,4-triazolo[1,5-a]pyrimidine (tp for 1), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp for 2) and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp for 3), have been synthesized and characterized by elemental analysis, infrared analysis, multinuclear magnetic resonance spectroscopic techniques (1H, 13C, 15N), and single-crystal X-ray diffraction (for 1 and 2). By assay with myoglobin, the photo-activated CO-releasing molecule (PhotoCORM) character of (1-3) has been confirmed, thus indicating the possibility of use in CO-based therapies. The importance of UV-induced modification has been investigated in the context of anticancer properties. Complexes (1) and (2) have been thoroughly screened for their in vitro cytotoxicity against various cancer cell lines: MCF-7 (breast cancer), HeLa (cervical cancer) and C32 (melanoma), as well as L929 normal fibroblasts in the dark and presence of UV-A light (365 nm). The results were compared with those for cisplatin and two reference ruthenium complexes, namely NAMI-A and KP1019. The most hydrophilic [Ru2(CO)4(μ-OOCCH3)2(tp)2] (1) (log P = -1.12) was found to be more cytotoxic than (2), despite the lower cellular uptake measured by ICP-MS toward HeLa cells. Importantly, photo-induced stimulation of cells with (1) resulted in a lower decrease in the viability of L929 normal cells (IC50 = 154.7 ± 6.5 μM) in comparison with HeLa cancer cells (IC50 = 66.7 ± 3.4 μM). The photo-induced stimulation of (1) and (2) increases ROS generation, and their anticancer activity may be a partially ROS-dependent phenomenon.

The understanding of the mechanism of Topo I inhibition by organic ligands is a crucial source of information that has led to the design of more effective and safe pharmaceuticals in oncological chemotherapy. The vast number of inhibitors that have been studied in this respect over the last decades have enabled the creation of a concept of an ‘interfacial inhibitor’, thereby describing the machinery of Topo I inhibition. The central module of action of this machinery is the interface of a Topo I/DNA/inhibitor ternary complex. Most of the ‘interfacial inhibitors’ are primarily kinetic inhibitors that form molecular complexes with an “on–off” rate timing; therefore, all of the contacts between the inhibitor and both the enzyme and the DNA are essential to keep the complex stable and reduce the “off rate”. To test this hypothesis, we designed the compound using a C-9-(N-(2′-hydroxyethyl)amino)methyl substituent in an SN38 core, with a view that a flexible substituent may bind inside the nick of a model of the DNA and stabilize the complex, leading to a reduction in the “off rate” of a ligand in a potential ternary complex in vivo. Using docking analysis and molecular dynamics, free energy calculations on the level of the MM-PBSA and MM-GBSA model, here we presented the in silico-calculated structure of a ternary complex involving the studied compound 1. This confirmed our suggestion that compound 1 is situated in a groove of the nicked DNA model in a few conformations. The number of hydrogen bonds between the components of a ternary complex was established, which strengthens the complex and supports our view. The docking analysis and free energy calculations for the receptor structures which were obtained in the MD simulations of the ternary complex 1/DNA/Topo I show that the binding constant is stronger than it was for similar complexes with TPT, CPT, and SN38, which are commonly considered as strong Topo I inhibitors. The binary complex structure 1/DNA was calculated and compared with the experimental results of a complex that was in a solution. The analysis of the cross-peaks in NOESY spectra allowed us to assign the dipolar interactions between the given protons in the calculated structures. A DOSY experiment in the solution confirmed the strong binding of a ligand in a binary complex, having a Ka of 746 mM−1, which was compared with a Ka of 3.78 mM−1 for TPT. The MALDI-ToF MS showed the presence of the biohybrid, thus evidencing the occurrence of DNA alkylation by compound 1. Because of it having a strong molecular complex, alkylation is the most efficient way to reduce the “on–off” timing as it acts as a tool that causes the cog to brake in a working gear, and this is this activity we want to highlight in our contribution. Finally, the Topo I inhibition test showed a lower IC50 of the studied compound than it did for CPT and SN38.

Derivatives of SN38 were synthesized that were either monosubstituted at C-5 or C-9 or disubstituted at both C-5 and C-9. Substitution to C-5 led to the generation of pairs of diastereomers (2c-2 h) in a one-pot reaction and was readily separable by HPLC. The absolute configurations of C-5 were established by electronic circular dichroism experiments. Compounds were tested in vitro against human cancer cell lines as well as a normal cell line. The impact of compounds 2a-2j on cancer cells is significant and the IC50 values against the normal cell line are several times higher than that of SN38. Using the Mannich reaction we obtained a new innovative group of derivatives with unique biological properties that preserves the high cytotoxicity in cancer cells and eliminates the acute toxicity to non-neoplastic cells, which can be considered a breakthrough in chemotherapy with the use of topoisomerase I inhibitors from the camptothecin family.

Novel nontoxic derivatives of SN38 with favorable antineoplastic properties were characterized in water solution using NMR. The phenomena observed by NMR were linked to basic pharmacological properties, such as solubility, bioavailability, chemical and stereochemical stability, and binding to natural DNA oligomers through the terminal G-C base pair, which is commonly considered a biological target of Topo I inhibitors. Compound 1, with bulky substituents at both C5(R) and C20(S) on the same side of a camptothecin core, manifests self-association, whereas diastereomers 2, with bulky C5(S) and C20(S) substituents are mostly monomeric in solution. The stereogenic center at C5 is stable in water solution at pH 5–6. The compound with an (N-azetidinyl)methyl substituent at C9 can undergo the retro Mannich reaction after a prolonged time in water solution. Both diastereomers exhibit different abilities in terms of binding to DNA oligomers: compound 1 is strongly bound, whereas the binding of compound 2 is rather weak. Molecular modeling produced results consistent with NMR experiments. These complementary data allow linking of the observed phenomena in NMR experiments to basic preliminary information on the pharmacodynamic character of compounds and are essential for planning further development research.

Three half-sandwich organometallic ruthenium(ii) complexes containing purine analogs such as triazolopyrimidines of general formula [(η6-p-cym)Ru(L)Cl2], where p-cym represents p-cymene and L is 5,6,7-trimethyl-1,2,4-triazolo[1,5-a]pyrimidine (tmtp for 1), 5,7-diethyl-1,2,4-triazolo[1,5-a]pyrimidine (detp for 2) and 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO for 3), have been synthesized and characterized by elemental analysis, infrared, multinuclear magnetic resonance spectroscopic techniques (1H, 13C, 15N), and single-crystal X-ray diffraction (for 1 and 2). All these complexes have been thoroughly screened for their in vitro cytotoxicity against MCF-7 and HeLa cell lines as well as L929 murine fibroblast cells, indicating [(η6-p-cym)Ru(HmtpO)Cl2] (3) as the most active representative against the HeLa cell line and simultaneously being 64-fold less toxic to normal L929 murine fibroblast cells than cisplatin. At the same time, 3 has shown antimetastatic activity comparable to NAMI-A against HeLa cells both after 24 and 48 h of treatment in a wound healing assay. In order to better understand the mechanism of anticancer action and differences in the cytotoxic activity of 1-3, the studies were expanded to determining their lipophilicity, the kinetic stability at pH 6.5-8, the effect on reactive oxygen species (ROS) production in HeLa cells and interactions with significant biomolecules (DNA and albumin) by using molecular docking and circular dichroism (CD) experiments. Furthermore, antiparasitic studies against L. braziliensis, L. infantum and T. cruzi reveal that the newly synthesized complexes 1-3 are very promising candidates which can compete with commercial antiparasitic drugs. Complex 3 in particular, on top of exhibiting a high antiparasitic effect (IC50 < 1 μM against two strains), reaches a selectivity index >1000.

In this account we present NMR based results of the interaction of 7-ethyl-9-hydroxymethyl-10-hydroxycamptothecin (1), a derivative of SN38, with a model nicked DNA decamer mimicking the wild type DNA target of Topoisomerase I inhibitors from the camptothecin family. The title compound 1 can be considered a main metabolite of phase I in the metabolic pathway of camptothecin derivatives bearing the alkylamino substituent. Therefore, its pharmacodynamic properties are of interest. It was established by DOSY (Diffusion Ordered Spectroscopy) that compound 1 forms a fairly stable molecular complex with a model nicked DNA decamer with affinity constant K-a 3.02 mM(-1). The analysis of NOESY experiments revealed intermolecular cross peaks and mutual induced shifts on both interacting components allowing the conclusion that guest molecule 1 is stacking the nitrogen bases inside the nick. MD (Molecular Dynamics) analysis of four possible inclusions of 1 inside the nick allows establishing the detailed geometry of a complex. Two conformations are suggested as the ones best representing the results of molecular modeling reconciled with experimental NOESY results. The aromatic core of both structures is stacking the nitrogen bases in a nick facing the unbroken strand with ring A. The protons in ring E interact with ribose protons of edge bases of a nick. In conclusion, it can be asserted that SN38 derivative 1 can effectively bind the molecular target of Topo I enzyme and play a role as a Topo I inhibitor.