Sunitinib (Sutent®) is a receptor tyrosine kinase (RTK) and angiogenesis inhibitor approved for the treatment of renal cell carcinomas, gastrointestinal stromal tumours and pancreatic neuroendocrine tumours.
A key structural motif retained throughout medicinal chemistry efforts during sunitinib's development was the indoline-2-one group. In the search for new anti-angiogenic scaffolds, we previously reported that non-indoline-2-one-based derivatives of semaxanib (SU5416, a structurally simpler sunitinib predecessor that underwent Phase III trials) are active as angiogenesis inhibitors, indicating that the group is not essential for activity. This Letter describes the synthesis and structure-activity relationships of another class of non-indoline-2-one angiogenesis inhibitors related to sunitinib/semaxanib; the 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones. A focussed library of 19 analogues was prepared using a simple novel process, wherein commercially available substituted arylacetic acids activated with an amide coupling reagent (HBTU) were reacted with the potassium salt of 3,5-dimethyl-1H-pyrrole-2-carbaldehyde in one-pot. Screening of the library using a cell-based endothelial tube formation assay identified 6 compounds with anti-angiogenesis activity. Two of the compounds were advanced to the more physiologically relevant rat aortic ring assay, where they showed similar inhibitory effects to semaxanib at 10μg/mL, confirming that 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones represent a new class of angiogenesis inhibitors.
Bioorganic & medicinal chemistry letters. 2016 Feb 15 [Epub ahead of print]
Nicholas S Kirk, Anna Bezos, Anthony C Willis, Pichit Sudta, Sunit Suksamrarn, Christopher R Parish, Marie Ranson, Michael J Kelso
Illawarra Health and Medical Research Institute, School of Chemistry, University of Wollongong, NSW 2522, Australia., Cancer and Vascular Biology Group, Department of Cancer Biology and Therapeutics, John Curtin School of Medical Research, Australian National University, Canberra ACT 2601, Australia., Single Crystal X-ray Diffraction Unit, Research School of Chemistry, Australian National University, Canberra ACT 2601, Australia., Division of Chemistry, Phetchaburi Rajabhat University, Phetchaburi 76000, Thailand; Department of Chemistry, Srinakharinwirot University, Bangkok 10110, Thailand., Department of Chemistry, Srinakharinwirot University, Bangkok 10110, Thailand., Cancer and Vascular Biology Group, Department of Cancer Biology and Therapeutics, John Curtin School of Medical Research, Australian National University, Canberra ACT 2601, Australia., Illawarra Health and Medical Research Institute, School of Biological Sciences, University of Wollongong, NSW 2522, Australia., Illawarra Health and Medical Research Institute, School of Chemistry, University of Wollongong, NSW 2522, Australia.