Phytotoxic cis-cinnamoyl glucosides from Spiraea thunbergii

Spiraea thunbergii Sieb. was found to contain 1- O- cis-cinnamoyl-β- d-glucopyranose and 6- O-(4′-hydroxy-2′-methylene-butyroyl)-1- O- cis-cinnamoyl-β- d-glucopyranose as major plant growth inhibitory constituents along with related compounds of lower phytotoxicity including 6- O-( trans-cinnamoyl)-1- O-(4″-hydroxy-3″-methyl-furan-2″-one)-β- d-glucopyranose, 6- O-(4′-hydroxy-2′-methylene-butyroyl)-1- O- trans-cinnamoyl-β- d-glucopyranose, and 1- O- trans-cinnamoyl-β- d-glucopyranose. The former three compounds were cinnamoyl glucosides. Major plant growth inhibitors in Spiraea thunbergii were found to be cis-cinnamoyl glucosides, 1 and 3. A trans-cinnamoyl glycoside 4 was also found.