Spirooxindol alkaloids from Voacanga africana: Targeting biofilm of MBLs producing Escherichia coli

•Seven unprecedented spirooxindole alkaloids were obtained from the stem barks of Voacanga Africana.•1 and 2 possess a unique indoleone system in conjugation with a 3,4ʹ-decahydroquinoline spiral ring originating from the seco-quinolhiddin core of the precursor.•Compounds 1 and 7 showed potent activity against MBLs producing E. coli 298 and 140, respectively.•Possible interaction sites of compounds 1 and 7 with membrane protein Bap were preliminarily explored by means of molecular docking.