Novel 1,2,4-oxadiazole compounds as PPAR-α ligand agonists: a new strategy for the design of antitumour compounds.

Modulation of PPAR-α by natural ligands is a novel strategy for the development of anticancer therapies. A series of 16 compounds based on the structure of 3-(pyridin-3-yl)-5-(thiophen-3-yl)-1,2,4-oxadiazole (natural compound) with antitumour potential were designed and synthesised. The cytotoxicity and PPAR agonist activity of these synthetic 1,2,4-oxadiazoles were evaluated in the A-498 and DU 145 tumour cell lines. Preliminary biological evaluation showed that most of these synthetic 1,2,4-oxadiazoles are less cytotoxic (sulforhodamine B assay) than the positive control WY-14643. Regarding the PPAR-α modulation, compound 16 was the most active, with EC 50 = 0.23-0.83 μM (PPAR-α). Additionally, compound 16 had a similar activity to the natural compound (EC 50 = 0.18-0.77 μM) and was less toxic in the RPTEC and WPMY-1 cell lines (non-tumour cells) (CC 50 = 81.66-92.67 μM) than the natural compound. Looking at the link between chemical structure and activity, our study demonstrates that changes to the natural 1,2,4-oxadiazole at the level of the thiophenyl residue can lead to new agonists of PPAR-α with promising anti-tumour activity.