Inhibitors of the glycine transporter type-2 (GlyT-2): synthesis and biological activity of benzoylpiperidine derivatives

A series of benzoylpiperidine analogs related to 4a was prepared, and their ability to inhibit the uptake of [(14)C]-glycine in COS7 cells transfected with human glycine transporter type-2 (GlyT-2) was evaluated. Small structural changes to the benzoylpiperidine region of the molecule led to a significant decrease in GlyT-2 inhibitory activity. In contrast, the distal aryl ring was more tolerant to functional group modifications and could accommodate a variety of substitutes at the C-2 or C-3 positions. Comparable activities to 4a were obtained by replacing the anilino nitrogen with an ether linkage 27 or by exchanging the isopropoxy ether moiety with an isopropyl amino group 15. A distinct preference for a 2-carbon tether (n=1) was observed relative to the corresponding 3-carbon homolog (n=2).     

Type II estrogen binding site agonist: synthesis and biological evaluation of the enantiomers of methyl-para-hydroxyphenyllactate (MeHPLA)

A high-affinity ligand for the type II estrogen binding site (EBS) was identified. Methyl para-hydroxyphenyllactate (MeHPLA) was observed to suppress the cellular proliferation of estrogen-sensitive MCF-7 breast cancer cells in vitro and to suppress the growth of rat uteri in vivo. The high affinity of MeHPLA for the type II EBS suggests that this interaction is responsible for the observed suppression of cell growth. In this study, the enantiomers of MeHPLA were synthesized and separated by three methods and evaluated for biological activity. When the methods were compared, it was found that the method using an optically pure amine to form the diastereomers of the enantiomers gave the superior yield. Binding studies for the enantiomers to the type II EBS showed that the S-MeHPLA had a higher affinity for the binding site. However, higher binding affinity did not translate into superior cell growth suppression. Both enantiomers suppressed cell growth equally.     

5'-modified agonist and antagonist (2'-5')(A)n analogues: synthesis and biological activity

Two 5'-modified (2'-5')(A)4 oligomers with an increased resistance to phosphatase degradation were synthesized and evaluated for their ability to develop an antiviral response when introduced into intact cells by microinjection or by chemical conjugation to poly(L-lysine). The enzymatic synthesis of 5'-gamma-phosphorothioate and beta,gamma-difluoromethylene (2'-5')(A)4 from adenosine 5'-O-(3-thiotriphosphate) and adenosine beta,gamma-difluoromethylenetriphosphate by (2'-5')-oligoadenylate synthetase is described. The isolation and characterization of these (2'-5')(A)4 analogues were achieved by high-performance liquid chromatography. The structures of 5'-modified tetramers were corroborated by enzyme digestion. These two 5'-modified tetramers compete as efficiently as natural (2'-5')(A)4 for the binding of a radiolabeled (2'-5')(A)4 probe to ribonuclease (RNase) L. Nevertheless, at the opposite to 5'-gamma-phosphorothioate (2'-5')(A)4, beta,gamma-difluoromethylene (2'-5')(A)4 failed to induce an antiviral response after microinjection in HeLa cells. In addition, it behaves as an antagonist of RNase L as demonstrated by its ability to inhibit the antiviral properties of 5'-gamma-phosphorothioate (2'-5')(A)4 when both are microinjected in HeLa cells. The increased metabolic stability of 5'-gamma-phosphorothioate (2'-5')(A)4 as compared to that of (2'-5')(A)4 was first demonstrated in cell-free extracts and then confirmed in intact cells after introduction in the form of a conjugate to poly(L-lysine). Indeed, 5'-gamma-phosphorothioate (2'-5')(A)4-poly(L-lysine) conjugate induces protein synthesis inhibition and characteristic ribosomal RNA cleavages for longer times than unmodified (2'-5')(A)4-poly(L-lysine) in the same cell system.(ABSTRACT TRUNCATED AT 250 WORDS)     

Polyamines antagonize both the antileukemic activity and the reverse transcriptase stimulatory activity of 4,4'-diacetyldiphenylurea bis(guanylhydrazone) (DDUG)

(Diacetyldiphenylurea)bis(guanylhydrazone) (DDUG) functions as a cationic trypanocide antagonized in vivo by exogenous concomitant addition of the biologically active polyamine, spermine. It also inhibits the DNA polymerases of L1210 murine leukemia cells. We have found that DDUG stimulates Rauscher murine leukemia virus DNA polymerase activity in a manner similar to polyamines. Such stimulation does not occur if DNA synthesis is carried out on spermine + activated DNA complexes. We also show that the in vivo antileukemic activity of DDUG in the L1210 ascites mouse model is antagonized by biologically active polyamines. These studies suggest a new intracellular target for the antileukemic activity of DDUG: interference with polyamine function.     

Ruthenium(III) maltolato-nitroimidazole complexes: synthesis and biological activity

The Ru(III) metronidazole-maltolato and -ethylmaltolato complexes, trans-[RuL₂(metro)₂]CF₃SO₃ (L = ma (1a) or etma (1b)), have been synthesized and tested for potential anti-tumour activity against the human breast cancer cell line MDA-MB-435S using a so-called MTT assay in phosphate-buffered saline; ma = 3-hydroxy-2-methylpyran-4-onato, etma = 2-ethyl-3-hydroxypyran-4-onato, metro = 2-methyl-5-nitro-1H-imidazole-1-ethanol (metronidazole); MTT = 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The complexes exhibit lower IC₅₀ values than our previously reported Ru(III) tris-maltolato and -ethylmaltolato complexes [D.C. Kennedy, A. Wu, B.O. Patrick, B.R. James, Inorg. Chem. 44 (2005) 6529–6535]. An improved synthetic route to the 2-nitroimidazole EF5 (2-(2-nitro-1-H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide) is reported, as well as a related synthesis of a 3-nitro-1,2,4-triazole derivative of EF5, triF5 (2-(3-nitro-1-H-triazol-1-yl)-N-(2,2,3,3,3- pentafluoropropyl)acetamide). The complexes [RuL₂(EF5)₂]CF₃SO₃ (4a and 4b) and [Ru(ma)₂(triF5)₂]CF₃SO₃ (5) were prepared from the [RuL₂(EtOH)₂]CF₃SO₃ complexes (3a and 3b); IC₅₀ values for 3–5 are high. Data on the uptake of Ru by the cells are also reported. The complexes were characterized generally by all or some of the following methods: elemental analyses, NMR, IR and mass spectroscopies, conductivity, and cyclic voltammetry; complexes 1a and 1b were also analyzed by X-ray crystallography.