1Dept Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Yokohama, 223–8522, Japan.
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa, JAPAN
*Correspondence author: E.Mail: p.piyatida@yahoo.com
Online published on 7 November, 2012.
Allelopathic activity of Piper sarmentosum Roxb. was determined and a potent growth inhibitory substance was isolated. The aqueous methanol extracts of P. sarmentosum inhibited the growth of 6-test plant species [cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), alfalfa (Medicago sativa L.), timothy (Phleum pretense L.), Italian ryegrass (Lolium multiflorum Lam.) and crabgrass (Digitaria sanguinalis L.)] to various degrees in a dose-dependent manner. The active substance 3-phenylpropionic acid was purified from the aqueous methanol extract of P. sarmentosum and identified by 1H-, 13C-NMR and MS. The threshold of 3-phenylpropionic acid for growth inhibition was 1 μM. The concentrations required for 50% growth inhibition of cress and lettuce were 1.2–9.3 μM and the concentrations required for 50% growth inhibition of timothy and Italian ryegrass were 4.7–51.8 μM. The endogenous concentration of 3-phenylpropionic acid in P. sarmentosum was 121 μmol/kg. Considering the endogenous level and the inhibitory activity, 3-phenylpropionic acid may work as allelopathic substance in P. sarmentosum through growth inhibition of neighbouring plant species.
Alfalfa, allelopathic activity, allelopathy, aqueous methanol extract, crabgrass, cress, lettuce, Italian ryegrass, Piper sarmentosum, timothy
