Growth-inhibitory activity of components in Cryptomeria japonica leaves against Robinia pseudoacacia.
Extracts obtained from Cryptomeria japonica leaves were tested for growth inhibition activity against Robinia pseudoacacia seeds, which is known as a representative invasive plant in temperate forests. Inhibitory activities against radicle and hypocotyl growth were found in hexane and ethyl acetate extracts but showed no or weak activity on seed germination. The extracts also showed inhibitory activity against Trifolium repens as a representative weed. The active extracts were fractionated by silica gel column chromatography and cryptomeridiol was isolated as an active compound. Comparison of activities between cryptomeridiol and β-eudesmol indicated that the diol structure of the eudesmane skeleton was important in causing the inhibitory activities.