Allelopathy Journal

In Petri dish bioassay, the allelopathic effects of different extracts (petroleum, ethyl acetate, n-butanol and aqueous) of Polygonatum odoratum rhizome were studied on the seed germination and growth of wheat, cucumber and carrot. The allelopathic inhibitory effects depended on the extracts concentration. All extracts inhibited the seed germination and shoot growth, however, petroleum extracts inhibited the root growth at higher concentrations but stimulated at lower concentrations. The ethyl acetate extracts proved most inhibitory followed by aqueous extracts, n-butanol extracts and petroleum extracts. Two rare C-methylated homoisoflavanones: 3-(4′-hydroxy-benzyl)-5,7-dihydroxy-6,8-dimethyl-chroman-4-one(1) and 3-(4′-hydroxy-benzyl)-5,7-dihydroxy-6-methyl-8-methoxy-chroman-4-one (2), were isolated and purified from the ethyl acetate extracts using silica gel and Sephadex LH-20 column chromatography. Their structures were identified using 1D and 2D NMR spectroscopy. Compound 2 was isolated from the Polygonum genus for the first time. Although the two isolated compounds did not inhibit seed germination, but were inhibitory to root and shoot growth of test spp. At 0.5 mg/ml concentration, the compound 1 inhibited the root growth of carrot and wheat by 84.6% and 88.2%, respectively, while, Compound 2 caused inhibition in carrot, cucumber and wheat by 87.9, 67.8 and 90.9%, respectively. These results indicated that P. odoratum may be allelopathic to succeeding crops.