Synthesis and QSAR study of novel cytotoxic spiro[3H-indole-3,2′(1′H)-pyrrolo[3,4-c]pyrrole]-2,3′,5′(1H,2′aH,4′H)-triones

1,3-Dipolar cycloaddition reaction of 1-aryl-1H-pyrrole-2,5-diones 1a-e with non-stabilized azomethine ylides, generated in situ via decarboxylative condensation of isatins 2a–c and sarcosine (3) in refluxing ethanol, afforded 4′-aryl-5′a,6′-dihydro-1′-methyl-spiro[3H-indole-3,2′(1′H)-pyrrolo[3,4-c]pyrrole]-2,3′,5′(1H,2′aH,4′H)-triones 4a–o in good yields. Compound 4l exhibited high anti-tumor activity against HEPG2 (liver cancer) cell line (IC50 = 12.16 μM) compared to that of Doxorubicin (IC50 = 7.36 μM), and the other synthesized compounds revealed moderate anti-tumor properties against HCT116 (colon), MCF7 (breast) and HEPG2 (liver) human tumor cell lines. 3D-Pharmacophore modeling and quantitative structure-activity relationship (QSAR) analysis were combined to explore the structural requirements controlling the observed anti-tumor properties. It was found that the major structural factors affecting potency of these compounds were related to their basic skeleton.

Graphical abstractAnti-tumor active 4′-aryl-5′a,6′-dihydro-1′-methyl-spiro[3H-indole-3,2′(1′H)-pyrrolo[3,4-c]pyrrole]-2,3′,5′(1H,2′aH,4′H)-triones were synthesized via dipolar cycloaddition reaction of azomethine ylides with 1-aryl-1H-pyrrole-2,5-diones.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Spiro[3H-indole-3,2′(1′H)-pyrrolo[3,4-c]pyrrole]-2,3′,5′(1H,2′aH,4′H)-triones were prepared. ► Antitumor properties of the synthesized compounds were screened. ► QSAR studies were conducted to understand the observed anti-tumor properties.