Platinum(IV) complexes with purine analogs. Studies of molecular structure and antiproliferative activity in vitro

Platinum(IV) compounds as potential drugs: a quantitative structure-activity relationship study

Introduction

Machine learning methods, coupled with a tremendous increase in computer power in recent years, are promising tools in modern drug design and drug repurposing.

Methods

Machine learning predictive models, publicly available at chemosophia.com, were used to predict the bioactivity of recently synthesized platinum(IV) complexes against different kinds of diseases and medical conditions. Two novel QSAR models based on the BiS algorithm are developed and validated, capable to predict activities against the SARS-CoV virus and its RNA dependent RNA polymerase.

Results

The internal predictive power of the QSAR models was tested by 10-fold cross-validation, giving cross-R2 from 0.863 to 0.903. 38 different activities, ranging from antioxidant, antibacterial, and antiviral activities, to potential anti-inflammatory, anti-arrhythmic and anti-malarial activity were predicted for a series of eighteen platinum(IV) complexes.

Conclusion

Complexes 1, 3 and 13 have high generalized optimality criteria and are predicted as potential SARS-CoV RNA dependent RNA polymerase inhibitors.

Synthesis, Physico-chemical Characterization, Crystal Structure and Influence on Microbial and Tumor Cells of Some Co(II) Complexes with 5,7-Dimethyl-1,2,4-triazolo[1,5-a]pyrimidine

Three complexes, namely [Co(dmtp)₂(OH₂)₄][CoCl₄] (1), [Co(dmtp)₂Cl₂] (2) and [Co(dmtp)₂(OH₂)₄]Cl₂∙2H₂O (3) (dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine), were synthesized and characterized by spectral (IR, UV-Vis-NIR), and magnetic measurements at room temperature, as well as single crystal X-ray diffraction. Complex (1) crystallizes in monoclinic system (space group C2/c), complex (2) adopts an orthorhombic system (space group Pbca), and complex (3) crystallizes in triclinic system (space group P1). Various types of extended hydrogen bonds and π-π interactions provide a supramolecular architecture for all complexes. All species were evaluated for antimicrobial activity towards planktonic and biofilm-embedded microbial cells and influence on HEp-2 cell viability, cellular cycle and gene expression.

Structure-cytotoxicity relationship for different types of mononuclear platinum(II) complexes with 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine

To compare the in vitro cytotoxicity of platinum(II) complexes with 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp), three complexes were prepared: cis-[PtI(2)(dbtp)(2)] (1), cis-[Pt(NO(3))(2)(dbtp)(2)] (2) and cis-[Pt(C(4)H(4)O(5))(dbtp)(2)] (3). The coordination compounds have been structurally characterized by IR; (1)H, (13)C, (15)N, (195)Pt NMR and single-crystal X-ray diffraction (1). Spectroscopic studies reveal the monodentate coordination of the heterocycle ligand (dbtp) via N(3) to platinum(II) ions. In addition, the crystal structure of (1) shows that the platinum(II) ion is located in nearly square-planar PtI(2)N(2) environments with two heterocycle ligands (dbtp) arranged in a head-to-head orientation. The complexes have been screened for their cytotoxicity against two human cells: non-small cell lung carcinoma (A549) and breast cancer (T47D). All of the complexes demonstrated a significant antiproliferative activity against both cell lines. On the basis of these results, it is concluded that the cytotoxicity of the studied compounds against T47D follows the order: (3)<(1)<(2).

Platinum(IV) coordination compounds containing 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one as nonleaving ligand. Molecular and cytotoxicity in vitro characterization

Novel platinum(IV) coordination compounds with 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO): cis-trans-[PtCl(2)(OH)(2)(NH(3))(HmtpO)] (1), cis-trans-[PtCl(5)(HmtpO)][(CH(3))(2)NH(2)] (2) have been prepared and structurally characterized by spectroscopic methods ((1)H, IR and X-ray crystallography (2)). The X-ray results indicate that the local geometry around the platinum(IV) centre approximates a typical octahedral arrangement with nitrogen atom N3 of the HmtpO and three chloride atoms in equatorial positions. The remaining two axial positions are occupied by two chlorides. The preliminary assessment of antitumor properties of (1) was performed as an in vitro antiproliferative activity against HL-60 human acute promyelocytic leukemia and HCV29T bladder cancer. The cis-trans-[PtCl(2)(OH)(2)(NH(3))(HmtpO)] (1) exhibits higher cytotoxic activity against HL-60 (IC(50)=6.4 μM) than cisplatin.

In vitro and in vivo antiparasital activity against Trypanosoma cruzi of three novel 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one-based complexes

Conventional reactions of the versatile multidentate ligand 5-methyl-1,2,4-triazolo[1,5-a] pyrimidin-7(4H)-one (HmtpO) with metallic(II) perchlorate salts lead to three novel multidimensional complexes [Cu(HmtpO)(2)(H(2)O)(3)](ClO(4))(2)·H(2)O (1), {[Cu(HmtpO)(2)(H(2)O)(2)](ClO(4))(2) ·2HmtpO}(n) (2) and {[Co(HmtpO)(H(2)O)(3)](ClO(4))(2)·2H(2)O}(n) (3). We have tested the antiparasital activity in vitro and in vivo of the three new complexes against Trypanosoma cruzi showing very promising results and overcoming clearly the reference drug commonly used for the Chagas disease treatment, benznidazole.

Biological activity of three novel complexes with the ligand 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one against Leishmania spp

OBJECTIVES

We report on new 1,2,4-triazolo[1,5-a]pyrimidine complexes that have been developed and examined for both antiproliferative in vitro activity against Leishmania infantum and Leishmania braziliensis, and report their possible mechanism of action on L. infantum and L. braziliensis.

RESULTS

Antileishmanial effects are described for newly synthesized Cu(II) and Co(II) complexes containing 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO) as a ligand. These complexes display a wide structural diversity: (i) mononuclear unit, [Cu(HmtpO)2(H2O)3](ClO4)2·H2O (1); (ii) two-dimensional framework, {[Cu(HmtpO)2(H2O)2](ClO4)(2)·2HmtpO}n (2); and (iii) chains, {[Co(HmtpO)(H2O)3](ClO4)(2)·2H2O}n (3). Compounds 1 and 2 appeared to be the most active against L. infantum (IC50 20.0 and 24.4 μM, respectively), and compounds 1 and 3 the most active against L. braziliensis (IC50 22.1 and 23.5 μM, respectively), with IC50s similar to those of the reference drug, glucantime (18.0 μM for L. infantum and 25.6 μM for L. braziliensis). These compounds were not toxic towards J774.2 macrophages. IC25 decreased infection capacity and severely reduced the multiplication of intracellular amastigotes, following the trend 1>3>2 for L. infantum and 3>1>2 for L. braziliensis. These complexes had an effect on the energy metabolism of the parasites at the level of the NAD+/NADH balance and the organelle membranes, causing their degradation and cell death.

CONCLUSIONS

Cellular proliferation, metabolic and ultrastructural studies showed that the compounds 2>1>3 were highly active against L. infantum and L. braziliensis.

Synthesis, molecular characterisation, and in vivo study of platinum(IV) coordination compounds against B16 mouse melanoma tumours

A novel platinum(IV) coordination compound with 6-mercaptopurine (6-Hmp) has been synthesised and characterised by IR and NMR spectroscopy. Spectroscopic parameters indicate the presence of two chelate (S-6, N-7) monodeprotonated ligands and two chloride ions in the coordination sphere of [PtCl2(6-mp)2] · H2O (I). Two Pt(IV) coordination compounds, [PtCl2(6-mp)2] · H2O (I) and [PtCl4(dbtp)2] (II), were used in the in vivo test against B16 mouse melanoma tumours. Cytotoxic activity of compound II against the tumour cells was found to be high (LC10 = 2.6 μM, LC50 = 17.0 μM, LC90 = 58.0 μM) compared to that of cisplatin.

Mono- and dinuclear platinum(II) compounds with 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine. Structure, cytotoxic activity and reaction with 5'-GMP

Mono- and dinuclear platinum(II) coordination compounds of formula cis-[PtCl(2)(NH(3))(dmtp)], 1, cis-[PtCl(2)(dmtp)(2)], 2 and {H(+)[C(28)H(32)Cl(2)N(16)Pt(2)](2+)(NO(3))(3)(H(2)O)(6)}, 3, in which dmtp is 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine have been synthesized and characterized by infrared and by (1)H, (13)C, (195)Pt NMR spectroscopy. The coordination units of the cationic species of formula [Pt(2)(mu-dmtp)(2)Cl(2)(dmtp)(2)](2+) are built up by two platinum atoms in a square-planar environment. Two sites are occupied by two 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) bridging ligands which are linked to both metal atoms through their nitrogen atoms in positions 3 and 4. The other two positions are occupied by one monodentate 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) molecule and a coordinated chloride. This compound is the first in which the same triazolopyrimidine ligand (dmtp) coordinates to a metal ion in two different ways, i.e. bridging bidentate and non-bridging monodentate. In addition, the interaction of compounds 1 and 2 with 5'-GMP was investigated in solution by (1)H NMR spectroscopy. The cytotoxicity of all the new platinum(II) compounds were studied by using two different cell lines: T47D (breast cancer) and HCV29T (bladder cancer).