Antiproliferative activities of halogenated thieno[3,2-d]pyrimidines

Abstract

The in vitro evaluation of thieno[3,2-d]pyrimidines identified halogenated compounds 1 and 2 with antiproliferative activity against three different cancer cell lines. A structure activity relationship study indicated the necessity of the chlorine at the C4-position for biological activity. The two most active compounds 1 and 2 were found to induce apoptosis in the leukemia L1210 cell line. Additionally, the compounds were screened against a variety of other microbial targets and as a result, selective activity against several fungi was also observed. The synthesis and preliminary biological results are reported herein.

Keywords: Antifungal; Apoptosis; Cytostatic; Heterocyclic chemistry; Thieno[3,2-d]pyrimidine.

Figure 1

The thieno[3,2-d]pyrimidine scaffold in drug design.

Figure 2

Thieno[3,2-d]pyrimidine as a component of the nucleobase scaffold.

Figure 3

MTT assays of cytotoxicity by 1 and 2 in L1210 cells. L1210 cells were treated with selected concentrations of compounds 1 (a) and 2 (b). After 48 h, cell viability was measured using MTT assays. Compound cytotoxicity was calculated by non-linear regression to a sigmoidal dose response function and is quoted as the IC₅₀.

Figure 4

Structure–activity relationship (SAR) for halogenated thieno[3,2-d]pyrimidines.

Figure 5

Cell cycle analyses of L1210 cells following treatment with 1 and 2. Cell cycle distributions of L1210 cells after 48 h in the presence of 0.32 μM compound 1, 5.4 μM compound 2, or vehicle control (DMSO) analyzed by flow cytometry of fixed, propidium iodide-stained cells. A minimum of 3000 cells were analyzed per cell population. Each bar represents the mean ± SD across 4 independent cell samples.

Figure 6

Apoptosis study on L1210 cell line. L1210 cells treated with (a) an equal volume of vehicle or (b) 1 μM compound 1. Similarly, L1210 cells were treated with (c) an equal volume of vehicle or (d) 5.4 μM compound 2. After 48 h, cells were stained using Annexin V and 7-ADD and analyzed by flow cytometry. A minimum of 10,000 cells were analyzed per condition, and subdivided into four categories: non-apoptotic/necrotic (bottom left), early apoptotic (bottom right), late apoptotic/necrotic (top right), and necrotic (top left). Percentages of total cells detected in each quadrant are indicated.

Scheme 1

Synthesis of substituted thieno[3,2-d]pyrimidines

Scheme 2

Synthesis of 7-bromo analogues.

Scheme 3

Synthesis of the thieno[3,2-d]pyrimidine C-nucleosides.

Scheme 4

Synthesis of halogenated pyrrolo[3,2-d]pyrimidine.