Isolation and Identification of Plant-Growth Inhibitory Constituents from Polygonum chinense Linn and Evaluation of Their Bioherbicidal Potential

Abstract

Polygonum chinense Linn. is a medicinal and invasive plant that belongs to the family Polygonaceae. The pharmacological activities and phytochemical constituents of Polygonum chinense are well reported, but the allelopathic effects and potent allelopathic substances of P. chinense remain to be investigated. Hence, this experiment was conducted to separate and characterize potentially allelopathic substances from an extract of the Polygonum chinense plant. The Polygonum chinense plant extracts highly suppressed the growth of cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), barnyard grass (Echinochloa crusgalli (L.) P. Beauv.), and timothy grass (Phleum pratense L.) seedlings in a species- and concentration-dependent way. Two active substances were separated using a series of purification procedures and determined through spectral analysis as (−)-3-hydroxy-β-ionone and (−)-3-hydroxy-7,8-dihydro-β-ionone. These two compounds significantly suppressed the seedling growth of Lepidium sativum (cress) at concentrations of 0.01 and 1 mM, respectively. The extract concentrations necessary for 50% growth inhibition (I50 values) of the cress hypocotyls and roots were 0.05 and 0.07 mM for (−)-3-hydroxy-β-ionone, respectively, and 0.42 and 1.29 mM for (−)-3-hydroxy-7,8-β-ionone, respectively. These findings suggest that these two compounds are in charge of the inhibitory effects of the Polygonum chinense extract and may serve as weed control agents.

Allelopathic Activity of a Novel Compound, Two Known Sesquiterpenes, and a C13 Nor-Isopenoid from the Leave of Croton oblongifolius Roxb. for Weed Control

“…Additionally, the I 50 values for the cress, lettuce, barnyard grass, and timothy shoot and root growth differed, indicating that inhibition via the C. oblongifolius extracts is species-dependent (Table 1). Similar outcomes of dose-and species-dependent inhibitory effects have been shown for extracts of Marsdenia tenacissima, Garcinia Xanthochymus, Polygonum chinense, and Anredera cordifolia [33][34][35][36]. Thus, the inhibitory activity of the C. oblongifolius extracts on the growth of the four examined plant species suggests that its extracts may possess phytotoxic substances.…”

Allelopathic Activity of the Invasive Plant Polygonum chinense Linn. and Its Allelopathic Substances

“…The above plant parts extracts of Polygonum chinense (Chinese knotweed) significantly inhibited the growth of alfalfa and Italian ryegrass ( Figure 2 ). Our previous experiment revealed that P. chinense plant extracts inhibited four test plants (cress, lettuce, timothy, and barnyard grass) [ 37 ]. The inhibitory effects of the plant extracts against the test plants increased with increasing extract concentration.…”

“…Isolating and identifying secondary metabolites from natural sources (plants) is crucial for the development of ecologically friendly natural herbicides. In our previous experiment, two active compounds, (-)-3-hydroxy- β -ionone and (-)-3-hydroxy-7,8-dihydro- β -ionone, were isolated and identified from P. chinense plant extracts, and both identified compounds significantly retarded the seedling growth of cress [ 37 ]. In the present study on the P. chinense above plant parts extracts, two other active compounds were purified and characterized as dehydrovomifoliol ( Figure 6 ) and loliolide ( Figure 8 ) using several chromatographic methods ( Figure 3 ).…”

“…Polygonum chinense is of particular interest experimentally because it has the ability not only to invade forests, habitats that are typically considered to be relatively suppressed by other plant species with their dense mats, but also to be used as herbal remedies. In our previous study, aqueous methanol extracts of P. chinense showed growth-inhibitory activity, and two inhibitory compounds were isolated [ 37 ]. Notably, there were other active fractions that may contain other inhibitory substances.…”

Isolation and identification of allelochemicals and their activities and functions

“…17). 111) These compounds suppressed the growth of Lepidium sativum at concentrations of 0.01 mM and 1 mM for compounds 30 and 31, respectively, and the IC 50 values on the growth of L. sativum were 0.05 mM and 0.42 mM for compounds 30 and 31, respectively. The allelopathic activity of compound 30 was 8-fold greater than that of compound 31.…”