Figure 1

Representative spiro[pyrrolidine-3, 3´-oxindole] natural and non-natural bioactive compounds, Spirotryptostatin A (1) (inhibits tubulin polymerization), Spirotryptostatin B (2) (inhibits cancer cells at G2/M phase of the cell cycle) and MI-5 (3) (inhibits p53-MDM2 protein-protein interaction).