Novel inhibitors for multidrug resistance: 1,3,5-triazacycloheptanes

Cascade Electrochemical Aerobic Oxygenation of 2-Substituted Indoles and Electrochemical [5 + 3] Annulation with Amidines: Access to Eight-Membered Benzo[1,3,5]triazocin-6(5H)-ones

The cascade electrochemical C3-selective aerobic oxygenation of 2-substituted indoles and electrochemical [5 + 3] annulation with amidines through an undivided cell galvanostatic method employing molecular oxygen and "electricity" as green oxidants was developed. This protocol provides an efficient and direct approach to eight-membered benzo[1,3,5]triazocin-6(5H)-ones. Mechanistic studies suggested that two subsequent electrochemical processes both proceeded through radical pathways.

Advances in 1,3,5-triazepines chemistry

This study reported the chemistry of 1,3,5-triazepines. Heterocyclic 1,3,5-triazepines are mono and fused cycles.

1,3,5-Triazepan-2,6-diones as Structurally Diverse and Conformationally Constrained Dipeptide Mimetics: Identification of Malaria Liver Stage Inhibitors from a Small Pilot Library

The development of the 1,3,5-triazepane-2,6-dione system as a novel, conformationally restricted, and readily accessible class of dipeptidomimetics is reported. The synthesis of the densely functionalized 1,3,5-triazepane-2,6-dione skeleton was achieved in only four steps from a variety of simple linear dipeptide precursors. To extend the practical value of 1,3,5-triazepane-2,6-diones, a general polymer-assisted solution-phase synthesis approach amenable to library production in a multiparallel format was developed. The conformational preferences of the 1,3,5-triazepane-2,6-dione skeleton were investigated in detail by NMR spectroscopy and X-ray diffraction. The ring exhibits a characteristic folded conformation which was compared to that of related dipeptide-derived scaffolds including the more planar 2,5-diketopiperazine (DKP). Molecular and structural diversity was increased further through post-cyclization appending operations at urea nitrogens. Preliminary biological screens of a small collection of 1,3,5-triazepane-2,6-diones revealed inhibitors of the underexplored malaria liver stage and suggest strong potential for this dipeptide-derived scaffold to interfere with and to modulate biological pathways.

Solid Phase Synthesis of 3,4,7-Trisubstituted 4,5,8,9-Tetrahydro-3H-imidazo[1,2-a][1,3,5]triazepin-2(7H)-thiones and N-Alkyl-4,5,7,8-tetrahydro-3H-imidazo[1,2-a][1,3,5]triazepin-2-amines

The solid-phase parallel synthesis of 3,4,7-trisubstituted 4,5,8,9-tetrahydro-3H-imidazo[1,2-a][1,3,5]triazepin-2(7H)-thiones and N-alkyl-4,5,7,8-tetrahydro-3H-imidazo[1,2-a][1,3,5]triazepin-2-amines starting from resin-bound dipeptides is described. The key synthetic steps involve the cylization of an amino and a guanidino functionality using thiocarbonyldiimidazole and the subsequent transformation of the resulting thiourea moiety to a substituted guanidine group using HgCl(2) and various amines. Following cleavage from the resin, the desired products were obtained in good yields and good to moderate purities, depending on the building blocks employed.

Solid-phase synthesis of 1,7-disubstituted-1,3,5-triazepane-2,4-diones

[reaction: see text]. The solid-phase synthesis of 1,7-disubstituted-1,3,5-triazepane-2,4-diones from resin-bound amino acids is described. The exhaustive reduction of solid-support bound amides with borane afforded the requisite secondary amines, which following treatment with phenyl isocyanatoformate and cleavage, provided the corresponding triazepane-2,4-diones.

Cellular resistance to mitomycin C is associated with overexpression of MDR-1 in a urothelial cancer cell line (MGH-U1)

OBJECTIVE

To compare multidrug resistance (MDR)-1 and MDR-3 gene expression in a new urothelial cancer cell line (MGHU-1, with resistance to mitomycin C) against controls and the established (epirubicin-resistant) MDR clone, and to correlate MDR with cytotoxicity data.

MATERIALS AND METHODS

Resistance to mitomycin C was induced by the long-term exposure of wild-type MGHU-1 cells to increasing concentrations (20-400 nmol/L) of mitomycin C. The cytotoxicity of mitomycin C or epirubicin was then compared in MGHU-1, MGHU-MMC (mitomycin C-resistant) and MGHU-1R (established MDR) cells, using the tetrazolium biomass assay. The expression of MDR-1 and -3 was investigated by the reverse transcriptase-polymerase chain reaction, using cDNA-specific primers after titration, and compared with DNA and negative controls.

RESULTS

MDR-1 and -3 were significantly and equally overexpressed in MGHU-1R, and associated with a dramatic increase in the 50% inhibitory drug concentration (P < 0.001) for mitomycin C and epirubicin against controls. In MGHU-MMC, the overexpression of MDR-1 was three times greater than that of MDR-3. The cytotoxicity profile for both agents was very similar to that of MGHU-1R. Trace amounts of MDR-1, but not MDR-3, were identified in the MGHU-1 wild-type.

CONCLUSIONS

Urothelial cancer cell resistance to mitomycin C is associated with cross-resistance to epirubicin and overexpression of MDR-1, suggesting that mitomycin C falls within the MDR category. Clinical application of this methodology may allow patients to be identified who are unlikely to benefit from intravesical chemotherapy.