Platinum-Based Antitumor Drugs Containing Enantiomerically Pure α-Trifluoromethyl Alanine as Ligand

Design and biological features of platinum (II) complexes with 3-hydroxy-3-(Trifluoromethyl)cyclobutane-1,1-Dicarboxylate as a leaving ligand

A series of platinum compounds 2a-5a and 2b-5b with fluoro-functional groups are designed and synthesized. Among them, complex 2b is the most effective agent with 3-hydroxy-3-(trifluoromethyl)cyclobutane-1,1-dicarboxylate as a leaving ligand, which showed better cytotoxic activity than compounds containing only CF₃ or OH group at 3-position of cyclobutane-1,1-dicarboxylate. The water solubility of 2a is better than that of carboplatin (32 mg/mL vs. 16 mg/mL), and its antitumor activity on A549 is 4.6-fold higher than that of carboplatin. The IC₅₀ value of 2b on A549 cells is 4.73 ± 0.64 μM, which is comparable to that of oxaliplatin and higher than that of carboplatin. Meanwhile, 2a and 2b are less toxic than oxaliplatin and cisplatin toward BEAS-2B cells. Moreover, 2a and 2b induce cell apoptosis in vitro by the Bax-Bcl-2-caspase-3 pathway and ferroptosis through inhibiting GPx-4 and elevating COX2. Results from in vivo experiment show that the inhibition rate of A549 xenograft tumor is cisplatin > 2b > oxaliplatin > 2a > carboplatin.

Toward the cholinesterase inhibition potential of TADDOL derivatives: Seminal biological and computational studies

Alzheimer's disease (AD) is a degenerative neurological disease characterized by gradual loss of cognitive skills and memory. The exact pathogenesis involved still remains unrevealed, but several studies indicate the involvement of an array of different enzymes, underlining the multifactorial character of the disease. Inhibition of these enzymes is therefore a powerful approach in the development of AD treatments, with promising candidates, including acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and monoamine oxidase. Interestingly, AChE is the target of a major pesticide family (organophosphates), with several reports indicating an intersection between the pesticide's activity and AD. In this study, various TADDOL derivatives were synthesized and their in vitro activities as AChE/BuChE inhibitors as well as their antioxidant activities were studied. Molecular modeling studies revealed the capability of TADDOL derivatives to bind to AChE and induce inhibition, especially compounds 2b and 3c furnishing IC₅₀ values of 36.78 ± 8.97 and 59.23 ± 5.31 µM, respectively. Experimental biological activities and molecular modeling studies clearly demonstrate that TADDOL derivatives with specific stereochemistry have an interesting potential for the design of potent AChE inhibitors. The encouraging results for compounds 2b and 3c indicate them as promising scaffolds for selective and potent AChE inhibitors.

Introduction of Fluorine into Antitumor-Active Dinuclear Platinum(II) Complexes Leads to Modulation of In Vivo Antitumor Activity in Mice

Tetrazolato-bridged dinuclear platinum(II) complexes ([{cis-Pt(NH₃)₂}₂(μ-OH)(μ-5-R-tetrazolato-N2,N3)]²⁺; tetrazolato-bridged complexes) show remarkable cytotoxic effects in vitro and antitumor activity in vivo. Here, we examined the structure-activity relationship of a series of fluorine-containing derivatives (R = CFH₂, CF₂H, or CF₃), focusing on their lipophilicity, cellular accumulation, cytotoxicity, interactions with a nucleobase and double-stranded deoxyribonucleic acid, and in vivo antitumor efficacy. Fluorination had a little effect on the properties of the derivatives in vitro; however, marked differences in in vitro cytotoxicity and in vivo tumor growth inhibition activity were observed. In BALB/c mice bearing colon-26 tumors, the antitumor efficacies of the derivatives were markedly altered, even by changing the number of fluorine atoms by one. In addition, one derivative, [{cis-Pt(NH₃)₂}₂(μ-OH)(μ-5-difluoromethyltetrazolato-N2,N3)](NO₃)₂, showed a significantly higher antitumor efficacy compared with oxaliplatin, a current first-line drug and the only platinum-based drug approved for the treatment of colon cancer. Together, the present results indicate that introducing fluorine into tetrazolato-bridged complexes may be useful for modulating in vivo activities.

Catalytic asymmetric synthesis of quaternary trifluoromethyl α- to ε-amino acid derivatives via umpolung allylation/2-aza-Cope rearrangement

In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement of tertiary α-trifluoromethyl α-amino acid derivatives for the preparation of a variety of quaternary α-trifluoromethyl α-amino acids in high yields with excellent enantioselectivities. The umpolung reactivity empowered by the activation of the key isatin-ketoimine moiety obviates the intractable enantioselectivity control in Pd-catalyzed asymmetric linear α-allylation. In combination with quasi parallel kinetic resolution or kinetic resolution, the generality of this method is further demonstrated by the first preparation of enantioenriched quaternary trifluoromethyl β-, γ-, δ- and ε-amino acid derivatives.

Asymmetric synthesis of quaternary α-trifluoromethyl α-amino acids by Ir-catalyzed allylation followed by kinetic resolution

Facile access to quaternary α-trifluoromethyl α-amino acids has been developed. This sequential reaction involves an Ir-catalyzed asymmetric allylation of α-trifluoromethyl aldimine esters followed by an unprecedented kinetic resolution.

Improving the anticancer activity of platinum(iv) prodrugs using a dual-targeting strategy with a dichloroacetate axial ligand

Four novel platinum(iv) complexes, characteristic of DCA/TFA and with chloride ions as axial ligands, were designed and synthesized. This type of platinum(iv) complexes 1a–2b exhibited significant cytotoxic activity, and the cytotoxicity of 1b was the greatest among these four complexes, which was 20.61 fold and 7.65 fold higher than that of cisplatin against HepG-2 and NCI-H460 cancer cells, respectively. The result from the apoptosis assay of 1b was consistent with the result from the cytotoxicity assay. In addition, complexes 1a and 1b induced cell cycle arrest at the S phase on HepG-2 cells. Taken together, our data showed that Pt(iv) complex 1b released the corresponding Pt(ii) complex and DCA, and induced apoptosis as well as disruption of the mitochondrial membrane potential, establishing Pt(iv) complex 1b as a potential dual-targeting anticancer agent.

Complex 1b could release complex B and DCA, playing a dual-targeting anti-tumor effect against cancer cells, targeting nuclear DNA and mitochondria, respectively.

Monofunctional platinum(II) complexes with potent tumor cell growth inhibitory activity: the effect of a hydrogen-bond donor/acceptor N-heterocyclic ligand

In this paper we investigate the possibility of further increase the role of the N-donor aromatic base in antitumor Hollis-type compounds by conferring the possibility to act as a hydrogen-bond donor/acceptor. Therefore, we synthesized the Pt(II) complex cis-[PtCl(NH3 )2 (naph)]NO3 (1) containing the 1,8-naphthyridine (naph) ligand. The naphthyridine ligand is generally monodentate, and the second nitrogen atom can act as H-bond donor/acceptor depending upon its protonation state. The possibility of forming such an H-bond could be crucial in the interaction of the drug with DNA or proteins. Apart from the synthesis of the compound, in this study we evaluated its in vitro antitumor activity in a wide panel of tumor cell lines, also including cells selected for their sensitivity/resistance to oxaliplatin, which was compared with that of previously reported complex 2 ([PtI(2,9-dimethyl-1,10-phenanthroline)(1-methyl-cytosine)]I) and oxaliplatin and cisplatin as reference compounds. The cytotoxicity data were correlated with the cellular uptake and the DNA platination levels. Finally, the reactivity of 1 towards guanosine 5'-monophosphate (5'-GMP) and glutathione was investigated to provide insights into its mechanism of action.

Synthesis and evaluation as antitumor agents of 1,4-naphthohydroquinone derivatives conjugated with amino acids and purines

We report on the synthesis of two series of 1,4-naphthohydroquinone derivatives conjugated with amino acids (Gly, Ala, Phe, and Glu) and with substituted purines linked by an aliphatic chain. The compounds were obtained through Diels-Alder cycloaddition between myrcene and 1,4-benzoquinone and evaluated in vitro for their cytotoxicity (GI50 ) against cultured human cancer cells of A-549 lung carcinoma, HT-29 colon adenocarcinoma, and MCF-7 breast carcinoma. The GI50 values found for some hydroquinone-amino acid and hydroquinone-purine hybrids against MCF-7 are in an activity range comparable to that of the reference drug doxorubicin.

Photophysical and computational studies of novel heterocyclic imidazole derivatives containing trifluoromethyl group substituent

Phenanthrimidazole ligands with potential electron withdrawing trifluoromethyl substituent have been synthesized and characterized using IR, mass and NMR spectral studies. The effect of solvent on their absorption and emission have been analysed in detail by Kamlet-Taft Catalan approach. The introduction of trifluoromethyl substituent results in a significant blue shift in emission when compared to its parent compound. This is due to the presence of the electron withdrawing trifluoromethyl moiety which changes the π-π conjugation of the cyclometalated ligand and lowers the triplet energy level, thus lowering the lowest unoccupied molecular orbital (LUMO) level. The optimized bond lengths, bond angles and dihedral angles calculated by DFT/B3LYP/6-31G (d,p) method are found to be slightly higher than that of XRD values of its parent compound. NBO, NLO, MEP and HOMO-LUMO energy analysis have been carried out by DFT method. This shows that the synthesized imidazole derivatives possess non-linear optical (NLO) behavior. In addition to these, calculations regarding the chemical potential, hardness and electrophilicity index have also been done.

Stereoselective access to fluorinated and non-fluorinated quaternary piperidines: synthesis of pipecolic acid and iminosugar derivatives

The preparation of optically pure quaternary piperidines, both fluorinated and non-fluorinated, has been achieved from a chiral imino lactone derived from (R)-phenylglycinol. In the case of the fluorinated derivatives, the addition of (trifluoromethyl)trimethylsilane (TMSCF(3)) followed by iodoamination and migration of the CF(3) group allowed access to four derivatives of α-(trifluoromethyl)pipecolic acid. A theoretical study of the CF(3)-group rearrangement has been carried out to help establish the reaction mechanism of this uncommon transformation. Moreover, a route to trifluoromethyl-substituted iminosugars was also developed through the diastereoselective dihydroxylation of suitable synthetic intermediates. Conversely, alkylation of the starting substrate and subsequent cross-metathesis and aza-Michael reactions led to α-alkyl derivatives of the target compounds.

DNA interaction studies of a platinum(II) complex, PtCl(2)(NN) (NN=4,7-dimethyl-1,10-phenanthroline), using different instrumental methods

The Pt(II) complex, PtCl(2)(4,7-Me(2)phen) (4,7-Me(2)phen=chelating dinitrogen ligand: 4,7-dimethyl-1,10-phenanthroline) was synthesized and characterized by spectroscopic ((1)H, (13)C NMR) and elemental analysis techniques. Binding interaction of this complex with calf thymus (CT) DNA has been investigated by emission, absorption, circular dichroism, viscosity and DNA thermal denaturation studies. The complex displays significant binding properties to the CT DNA. In fluorimeteric studies, the binding mode of complex with CT DNA was studied by using methylene blue as a fluoresce probe. As evidenced by the increasing fluorescence of methylene blue-DNA solutions in presence of increasing amount of complex, PtCl(2)(NN) complex is able to displace the methylene blue intercalated into DNA completely as to indicate intercalation. Furthermore, mentioned complex induces detectable changes in the CD spectrum of CT-DNA, an increase in T(m) value, and an increase in its viscosity. The experimental results showed that Pt(II) complex bound to DNA by an intercalative mode of binding.

Concise Synthesis of Enantiopure α-Trifluoromethyl Alanines, Diamines, and Amino Alcohols via the Strecker-type Reaction

Diastereomerically pure alpha-trifluoromethyl alpha-amino nitriles obtained by Strecker-type reactions from chiral CF3 imines and iminium proved to be very attractive versatile intermediates for the synthesis of various alpha-trifluoromethyl amino compounds. From these synthons, both enantiomers of alpha-trifluoromethyl alanine, trifluoromethyl 1,2-diamines, and amino alcohols were conveniently obtained in enantiopure form in high yields in a few steps.