Synthesis and DNase I Inhibitory Properties of New Squaramides.

Three new monosquaramides (3a-c) were synthesized, characterized by IR, NMR and X-ray, and evaluated for inhibitory activity against deoxyribonuclease I (DNase I) and xanthine oxidase (XO) in vitro. The target compounds inhibited DNase I with IC50 values below 100 µM, being at the same time more potent DNase I inhibitors than crystal violet, used as a positive control. 3-Ethoxy-4-((1-(pyridin-3-yl)propan-2-yl)amino)cyclobut-3-ene-1,2-dione (3c) stood out as the most potent compound, exhibiting a slightly better IC50 value (48.04 ± 7.98 µM) compared to the other two compounds. In order to analyze potential binding sites for the studied compounds with DNase I, a molecular docking study was performed. Compounds 3a-c are among the most potent small organic DNase I inhibitors tested to date.

3'-Methyl-4-thio-1H-tetrahydropyranspiro-5'-hydantoin platinum complex as a novel potent anticancer agent and xanthine oxidase inhibitor.

In this study, a Pt(IV) complex with 3'-methyl-4-thio-1H-tetrahydropyranspiro-5'-hydantoin (complex 1) was synthesized. The structure was determined via elemental analyses, infrared, 1 H, and 13 C nuclear magnetic resonance techniques. Density functional theory calculations were applied to optimize the molecular geometry and to calculate structural parameters and vibrational frequencies. The cytotoxicity of the newly synthesized complex 1 was assessed against K-562 and REH cells and compared with the cytotoxic effects of the ligand (L) and its Pd(IV) complex (complex 2). Complex 1 exhibited a better cytotoxic activity (IC50 = 76.9 µM against K-562 and 15.6 µM against REH cells) than L and complex 2, which was closer to the cytotoxic effect of cisplatin (IC50 = 36.9 µM and 1.07 µM against K-562 and REH cells, respectively), as compared with the ligand and complex 2. L and its complexes 1 and 2 were evaluated for inhibitory activity against xanthine oxidase (XO) in vitro, as compared with allopurinol (IC50 = 1.70 µM). Complex 1 was shown as a potent XO inhibitor, with an IC50 value of 19.33 µM, and the binding mode with the enzyme was predicted by molecular docking. Its inhibitory activity against XO is a potential advantage that might result in improved profile and anticancer activity.

Chloro-substituted pyridine squaramates as new DNase I inhibitors: Synthesis, structural characterization, in vitro evaluation and molecular docking studies.

Having continued our recent study on the synthesis and DNase I inhibition of several monosquaramides, two new chloro-substituted pyridine squaramates were synthesized and their structure was identified by X-ray. Their inhibitory properties towards deoxyribonuclease I (DNase I) and xanthine oxidase (XO) were evaluated in vitro. 3-(((6-Chloropyridin-3-yl)methyl)amino)-4-ethoxycyclobut-3-ene-1,2-dione (compound 3a) inhibited DNase I with an IC50 value of 43.82 ± 6.51 µM, thus standing out as one of the most potent small organic DNase I inhibitors tested to date. No cytotoxicity to human tumor cell lines (HL-60, MDA-MB-231 and MCF-7) was observed for the tested compounds. In order to investigate the drug-likeness of the squaramates, the ADME profile and pharmacokinetic properties were evaluated. Molecular docking was performed to reveal the binding mode of the studied compounds on DNase I.

Platinum complexes with 5-methyl-5(4-pyridyl)hydantoin and its 3-methyl derivatives: synthesis and cytotoxic activity - quantitative structure-activity relationships.

3,5-Dimethyl-5-(4-pyridyl)hydantoin (L) and its platinum(II) and platinum(IV) complexes with the general formula cis-[PtL(2) X(2) ] · n H(2) O and [PtL(2) Cl(4) ], where XCl, I and n = 2-4 were synthesized. A new Pt(IV) complex with 5-methyl-5-(4-pyridyl)hydantoin (L') with the formula cis-[Pt(L')(2) Cl(2) (OH)(2) ] · 5 H(2) O was also synthesized. The novel compounds were characterized by elemental analysis, IR, (1) H-, (13) C-, (195) Pt-NMR spectra and molar conductivity. The cytotoxic effects of these complexes were examined on three human tumor cell lines by MTT-dye reduction assay. These four new Pt(II) and Pt(IV) complexes and a set of another twelve Pt(II), Pt(IV), and Pd(II) complexes previously synthesized and tested were compiled and a QSAR model was derived in order to direct the further rational synthesis.

3-Amino-5-methyl-5-(4-pyrid-yl)hydantoin.

The title compound, 3-amino-5-methyl-5-(4-pyrid-yl)imid-azol-idine-2,4-dione, C(9)H(10)N(4)O(2), was obtained by reaction of 5-methyl-5-(4-pyrid-yl)hydantoin with hydrazine. It crystallizes as a racemate in the tetra-gonal space group I4(1)/a with one mol-ecule in the asymmetric unit. The dihedral angle between the pyridine ring and the five-membered hydantoin ring is 47.99 (3)° In the crystal structure, mol-ecules are joined in a three-dimensional hydrogen-bonded network by N-H⋯N and N-H⋯O links.

Synthesis, Spectroscopic Properties, Crystal Structure And Biological Evaluation of New Platinum Complexes with 5-methyl-5-(2-thiomethyl)ethyl Hydantoin.

BACKGROUND: The accidental discovery of Cisplatin's growth-inhibiting properties a few decades ago led to the resurgence of interest in metal-based chemotherapeutics. A number of well-discussed factors such as severe systemic toxicity and unfavourable physicochemical properties further limit the clinical application of the platinating agents. Great efforts have been undertaken in the development of alternative platinum derivatives with an extended antitumor spectrum and amended toxicity profile as compared to the reference drug cisplatin. The rational design of conventional platinum analogues and the re-evaluation of the empirically derived "structure- activity" relationships allowed for the synthesis of platinum complexes with great diversity in structural characteristics, biochemical stability and antitumor properties. METHODS: The new compounds have been studied by elemental analyses, IR, NMR and mass spectral analyses. The structures of the organic compound and one of the new mixed/ammine Pt(II) complexes were studied by X-ray diffraction analysis. The cytotoxic effects of the compounds were studied vs. the referent antineoplastic agent cisplatin against four human tumour cell lines using the standard MTT-dye reduction assay for cell viability. The most promising complex 3 was investigated for acute toxicity in male and female H-albino-mice models. RESULTS: A new organic compound (5-methyl-5-(2-thiomethyl)ethyl hydantoin) L bearing both S- and Ncoordinating sites and three novel platinum complexes, 1, 2 and 3 were synthesized and studied. Spectral and structural characterization concluded monodentate S-driven coordination of the ligand L to the metal center in complexes 1 and 2, whereas the same was acted as a bidentate N,S-chelator in complex 3. Ligand L crystallizes in the tetragonal space group I41/a (No 88) with one molecule per asymmetric unit. While complex 3 crystallizes in the monoclinic space group P21/c (No 14) with one molecule per asymmetric unit. In the same complex 3, the platinum ion coordinates an L ligand, a chloride ion and an ammonia molecule. In the in vitro experiments, the tested L and complexes 1 and 2 exhibited negligible cytotoxic activity in all tumor models. Accordingly, complex 3 is twice as potent as cisplatin in the HT-29 cells and is at least as active as cisplatin on the MDA-MB-231 breast cancer cell line. In the in vivo toxicity estimation of complex 3 no signs of common toxicity were observed. CONCLUSION: The Pt(II)-bidentate complex 3 exhibited significant cytotoxic potential equaling or surpassing that of the reference drug cisplatin in all the tested tumor models. Negligible anticancer activity on the screened tumor types has been shown by the ligand L and its Pt(II) and Pt(IV) complexes 1 and 2, respectively. Our study on the acute toxicity of the most active complex 3 proved it to be non-toxic in mice models.

Synthesis, characterization and biological activity of Pt(II) and Pt(IV) complexes with 5-methyl-5(4-pyridyl)-2,4-imidazolidenedione.

New platinum(II) and platinum(IV) complexes with 5-methyl-5(4-pyridyl)-2,4-imidazolidenedione and various halogen ions with general formula [PtL(2)X(2)] and [PtL(2)Cl(4)], where L is the organic ligand and X is Cl(-), Br(-), J(-), were synthesized. The molecular formulae of all the complexes were confirmed by elemental analysis, IR, (1)H, (13)C NMR spectral analyses and molar conductivity. The cytotoxic effects of these complexes were examined on some human tumor cell lines. The newly synthesized cis-[PtL(2)Cl(2)] exerted cytotoxic activity against SKW-3, MCF-7, EJ, U-266 tumor cell lines, while cis-[PtL(2)Br(2)], trans-[PtL(2)I(2)] were less active. The higher oxidation state complex cis-[PtL(2)Cl(4)] was inactive in all cell lines but in SKW-3 some augmentation of the cytotoxicity was seen after co-administration of ascorbic acid but not when treated in combination with reduced glutathione or N-acetylcysteine. A DNA-fragmentation analysis revealed that the cytotoxicity of the dichloro analogue, characterized with superior activity compared to the other complexes, is mediated by induction of apoptotic cell death.

Cellular pharmacology, antineoplastic activity and low in vivo toxicity of a carboxylato-bridged platinum(II) complex bis(acetato)diammine-bis-micro-acetato diplatinum (II) dihydrate.

The dinuclear platinum complex bis(acetato)diammine-bis-micro-acetato diplatinum (II) dihydrate has been previously shown to exert profound cytotoxicity in diverse tumor cell lines, while being far less detrimental than the clinically applied platinum drugs against some susceptible to platinum toxicity non-malignant cellular populations. In the present study we report the investigation of the cellular accumulation kinetics and apoptosis induction of the dinuclear complex in K-562, its potent in vivo antineoplastic activity against L1210 leukemia and Lewis lung carcinoma tumor models and its lower nephrotoxicity, myelosuppressive potential and clastogenicity in vivo relative to cisplatin.

Novel approaches towards development of non-classical platinum-based antineoplastic agents: design of platinum complexes characterized by an alternative DNA-binding pattern and/or tumor-targeted cytotoxicity.

Cisplatin is an essential antineoplastic agent whose introduction in clinical use revolutionized the treatment of several solid malignancies, especially those of germinative origin. The unfavorable toxicological profile of this drug, however as well as the resistance of some common malignancies solicited the search of platinum complexes, characterized by lower toxicity and/or broader antitumor spectrum. Thus during the last three decades a plethora of several thousand platinum coordination compounds have been synthesized and evaluated as potential antineoplastic agents. Despite of the numerous compounds investigated however only few of the proved to be of clinical significance and actually none of them could be considered as an ideal substitute for cisplatin regarding both lower toxicity and broader spectrum of anticancer activity. To a great extent the platinum-based drug discovery was confined at structural modification of the parent compound in line with the classic structure-activity relationship concept. Conversely, since the majority of platinum complexes developed so far are closely related structural analogues of cisplatin, it is not surprising that they produce similar cellular effects and any altered pattern of antitumor activity and/or toxicity is likely to be due to pharmacokinetic, rather than truly mechanistic, factors. Studies over the last few years have shown that the structural resemblance to cisplatin is not an absolute requirement for cytotoxicity, which broadens the search for cisplatin analogues towards non-classical compounds with prominent structural/pharmacodynamic dissimilarity to the prototype. This review covers the major approaches to elaboration of non-classical platinum complexes with emphasis on complexes interacting with DNA in a cisplatin-dissimilar fashion and complexes with tumor-targeted cytotoxicity.

Synthesis, physicochemical and in vitro pharmacological investigation of new platinum (II) complexes with some cycloalkanespiro-5'-hydantoins.

Platinum (II) complexes with cyclobutanespiro-5'-hydantoin and cycloheptanespiro-5'-hydantoin were synthesized and evaluated by means of general physicochemical methods. The data from the elemental analysis, IR and NMR spectra suggested the formation of cis-[Pt(C6H8N2O2)2(NH3)2](NO3)2 x 4H2O (PtCBH), when cyclobutanespiro-5'-hydantoin was used as a ligand and cis-[Pt(C9H14N2O2)(NH3)2](NO3)2 x 4H2O (PtCHTH), when cycloheptanespiro-5'-hydantoin was used, respectively. The novel complexes exerted cytotoxic effects at micromolar concentrations against a panel of human tumor cell lines. They were found to trigger apoptosis in HL-60 and BV-173 cells as evidenced by DNA-laddering detection. The evaluation of the effects of PtCBH, PtCHTH and the antineoplastic drugs cisplatin and oxaliplatin against cultured murine kidney epithelial cells revealed that the hydantoin complexes were far less nephrotoxic in vitro.

Synthesis, physicochemical investigation and cytotoxic activity of new Pt(II) complexes with hydantoin ligands.

The interaction of cis-dichlorodiaminplatinum(II) (cis-DDP) with 2,4-imidazolidenedione-5-methyl-5-phenyl was studied. The method of preparation of the new Pt(II) complex consisted in precipitation of chloride ions from cis-DDP via a diaqua complex and reaction with the ligand in water-organic media. On the basis of IR spectra, (1)H- and (13)C-NMR analysis the coordination mode of the ligand and most fitting structures of two isomeric complexes were proposed. The pharmacological investigations revealed that the new Pt(II) complex with 5-methyl-5-phenylhydantoin (PtMPH) as well as the previously described Pt(II) complexes with cyclopentanespiro-5'-hydantoin and cyclohexanespiro-5'-hydantoin (PtCHH) exerted concentration-dependent cytotoxic effect in a panel of human tumor cell lines. On the basis of the IC(50) values obtained PtMPH proved to be the most active cytotoxic agent. The other investigated complexes were less active, and among them PtCHH was the least potent antineoplastic agent. The pharmacodynamic investigation of PtMPH showed that this compound induces programmed cell death (apoptosis), as evidenced by the detection of oligonucleosomal DNA fragmentation in HL-60 cells after treatment with PtMPH.

In vitro biochemical and pharmacological evaluation of a novel cytotoxic dinuclear platinum(II) complex with 3-amino-5-methyl-5-phenylhydantoin.

An in vitro pharmacological evaluation of a novel dinuclear platinum complex ([KL(2)](2)[Pt(2)I(6)], where L is 3-amino-5-methyl-5-phenylhydantoin; Ad-1) was carried out. The cytotoxicity of [KL(2)](2)[Pt(2)I(6)] against human tumor cell lines was assessed using the MTT [-3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide] assay. The complex exerted concentration-dependent cytotoxic effects that were comparable or even superior to that of cisplatin. Moreover, the novel complex retained significant activity against CaCo-2 and Neuro-2A cells, which showed primary resistance to cisplatin. As evidenced by the rising level of genomic DNA fragmentation following treatment with [KL(2)](2)[Pt(2)I(6)], the cytotoxic effects are at least partly mediated by induction of apoptosis. The DNA binding of [KL(2)](2)[Pt(2)I(6)] and cisplatin were assessed using a 40-base fragment, whereby the present GG-motif is the recognition sequence of the nuclease BamH1. The DNA platination was determined after BamH1 treatment, 5% PAGE, and ethidium bromide staining. Cisplatin completely inhibited the BamH1-mediated fragmentation of the target DNA molecule. [KL(2)](2)[Pt(2)I(6)] also significantly inhibited the fragmentation of the target DNA sequence. The platination induced by [KL(2)](2)[Pt(2)I(6)] was better repaired by the nucleotide excision repair than the cisplatin lesions. As evidenced by electrophoresis mobility shift assay, the Ad-1-modified DNA was efficiently recognized and bound by the high mobility group box (HMGB)-1 protein, a member of the HMG domain proteins, which implies that the latter are most probably important for the cytotoxicity mode of action of this agent.

In vitro toxicological evaluation of a dinuclear platinum(II) complex with acetate ligands.

In the present study the toxicological potential of a tumor-inhibiting dinuclear platinum(II) complex (bis(acetato)diammine-bis-micro-acetato diplatinum(II) dihydrate (BAP)) was evaluated, utilizing in vitro models of nephrotoxicity, myelosuppression and neurotoxicity. Regarding the discrepancies between the hallmark toxicity of the clinically utilized platinum drugs, we used three distinct referent compounds as follows cisplatin for the assessment of in vitro nephrotoxicity, carboplatin in case of cultured bone marrow cells and oxaliplatin for the determination of the in vitro neurotoxicty, respectively. The results obtained indicate that the investigated dinuclear complex is endowed by a lower potential to induce detrimental effects upon these typically susceptible platinum toxicity cellular populations as compared to the corresponding referent drugs. These findings, together with the previously encountered profound cytotoxic efficiency of this dinuclear platinum(II) complex against human tumor cell lines, recall for a further detailed evaluation of BAP as potential antineoplastic agent.