The discovery of new compounds for the pharmacological manipulation of protein function often embraces the screening of compound collections, and it is widely recognized that natural products offer beneficial characteristics as protein ligands. Much effort has therefore been focused on “natural product-like” libraries, yet the synthesis and screening of such libraries is often limited by one or more of the following: modest library sizes and structural diversity, conformational heterogeneity, and the costs associated with the substantial infrastructure of modern high-throughput screening centers. Here, we describe the design and execution of an approach to this broad problem by merging principles associated biologically-inspired oligomerization and the structure of polyketide-derived natural products. A novel class of chiral and conformationally-constrained oligomers is described (termed “chiral oligomers of pentenoic amides” – COPAs) that offers compatibility with split-and-pool methods and can be screened en masse in a batch mode. We demonstrate that a COPA library containing 160,000 compounds is a useful source of novel protein ligands by identifying a non-covalent synthetic ligand to the DNA-binding domain of the p53 transcription factor.

Here, we report the design of new analogues of spirooxoindolepyrrolidine nucleus as modulators of p53 activity. Compounds (3R,7aR)-6-(4-chlorobenzyl)-1H-spiro[imidazo[1,5-c]thiazole-3,3'-indoline]-2',5,7(6H,7aH)-trione (9c) and (3R,7aR)-5'-methyl-6-(3,4,5-trimethoxybenzyl)-1H-spiro[imidazo[1,5-c]thiazole-3,3'-indoline]-2',5,7(6H,7aH)-trione (10d) are the most potent compounds of this series, inhibiting cell growth of different human tumor cells at submicromolar and micromolar concentrations, respectively. Compound 9c induces apoptotic cell death in human melanoma cell line M14 at 24 h, while in the same condition, treatment with 10d showes a clear arrest at G2/M phase inducing delay of cell cycle progression. Possibly, these activities may be due to inhibition of p53-MDM2 interaction and subsequent p53 release and activation.

In patients with chronic lymphocytic leukemia (CLL), a single neoplastic antigen-specific B cell accumulates and overgrows other B cells, leading to immune deficiency. CLL is often treated with drugs that ablate all B cells, leading to further weakening of humoral immunity, and a more focused therapeutic strategy capable of targeting only the pathogenic B cells would represent a significant advance. One approach to this would be to develop synthetic surrogates of the CLL antigens allowing differentiation of the CLL cells and healthy B cells in a patient. Here, we describe discovery of non-peptidic molecules capable of targeting antigen-specific B cell receptors with good affinity and selectivity using a combinatorial library screen. We demonstrate that our hit compounds act as synthetic antigen surrogates and recognize CLL cells and not healthy B cells. Additionally, we argue that the technology we developed can be used for discovery of other classes of antigen surrogates.

Analogues of the previously reported potent cytotoxic spiro[(dihydropyrazine-2,5-dione)-6,3'-(2',3'-dihydrothieno[2,3-b]naphtho-4',9'-dione)] derivatives (3, 3') were prepared to explore new structural requirements at the diketopiperazine domain for the cytotoxic activity. The in vitro activity was evaluated against the MCF-7 human breast carcinoma and SW 620 human colon carcinoma cell lines. The 4-[(2-N, N-dimethyl)amino]ethyl (6i), and the 4-(2-pyrrolydin)ethyl (6l) derivatives emerged as the most potent compounds of this series, with a cytotoxic activity comparable to that of doxorubicin. These compounds, in both racemic and pure enantiomeric forms, showed also a high efficacy in cell lines resistant to doxorubicin (MCF-7/Dx) and in cell lines that were highly resistant to treatment with doxorubicin, such as HEK-293 (kidney), M-14 (melanoma), and HeLa (cervical adenocarcinoma) human cell lines. In addition, the effects on growth and cell cycle progression in CaCo-2 cell line (colon adenocarcinoma) and DNA-binding properties were investigated.