Two Allelopathic Substances from Plumbago rosea Stem Extracts and Their Allelopathic Effects

Abstract

The plant Plumbago rosea Linn., belonging to the Plumbaginaceae family, is an important medicinal herb distributed in part of Southeast Asia, and there are many reports of its pharmacological properties. However, the allelopathic activities of P. rosea have not been examined. Thus, the present study was conducted to assess the allelopathic activity of P. rosea and to identify its allelopathic substances. The aqueous methanol stem extract of P. rosea significantly suppressed the seedling growth of barnyard grass (Echinochloa crus-galli L. P. Beauv.), Italian ryegrass (Lolium multiflorum Lam.), timothy (Phleum pretense L.), cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), and alfalfa (Medicago sativa L.). The extract of P. rosea was then purified through chromatographic steps, and two active substances were isolated and determined as 7,4′,5′-tri-O-methyl dihydroquercetin and 7,4′,5′-tri-O-methylampelopsin. The two compounds significantly inhibited the seedling growth of cress, with 7,4′,5′-tri-O-methylampelopsin showing a greater inhibitory effect than 7,4′,5′-tri-O-methyl dihydroquercetin. This result may be due to the 3′-OH group in 7,4′,5′-tri-O-methylampelopsin. The effective concentrations of both compounds required for 50% growth inhibition (EC50 values) of cress seedlings were 0.24 mM and 0.59 mM for root and shoot, and 0.07 mM and 0.21 mM, respectively. These findings suggest that the two compounds may contribute to the allelopathic effect of P. rosea and could be used as a natural source of allelopathic substances.

Allelopathic Potential of Marsdenia tenacissima (Roxb.) Moon against Four Test Plants and the Biological Activity of Its Allelopathic Novel Compound, 8-Dehydroxy-11β-O-Acetyl-12β-O-Tigloyl-17β-Marsdenin

“…Additionally, the I 50 values of the shoot and root growth of the four test plants varied, showing that the inhibition by the M. tenacissima extracts was species dependent (Table 1). A similar trend in concentration and species-dependent inhibitory activity for extracts of Elaeocarpus floribundus, Anredera cordifolia, Garcinia xanthochymus, and Plumbago rosea have also been reported [39][40][41][42]. Therefore, the M. tenacissima leaf extracts may contain allelopathic substances responsible for the growth-inhibitory activities against the four tested plants.…”

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

“…The species- and concentration-dependent inhibitory effects are also consistent with many research findings on different plant extracts of Leucas cephalotes (Roth) Spreng [ 51 ], Annona muricana (L.) [ 52 ], Senna garrettiana [ 53 ], Dregea volubilis (L.f.) [ 29 ], Elaeocarpus floribundus Blume [ 30 ], Marsdenia tenacissima (Roxb.) Moon [ 31 ], and Plumbago rosea [ 32 ]. In addition, the I 50 values revealed that the roots of the four tested plants were more susceptible to extracts of P. chinense than the hypocotyls/ coleoptiles.…”

“…Several have researchers also documented that the root and hypocotyl growth of L. sativum is significantly suppressed by loliolide, cis-3-hydroxy- α -ionone, and (3R)-3-hydroxy- β -ionone isolated from Elaeocarpus floribundus Blume [ 30 ]; a novel compound of steroidal glycoside 1 and common compound steroidal glycoside 2, isolated from Marsdenia tenacissima (Roxb.) Moon leaves extracts [ 31 ]; 7,4′,5′-tri- O -methylampelopsin and 7,4′,5′-tri- O -methyl dihydroquercetin isolated from Plumbago rosea [ 32 ]; a novel compound of garcienone, isolated from Garcinia xanthochymus Hook [ 33 ]. In addition, four characterized allelochemicals of (−)-catechin, (−)-epicatechin, resveratroloside, and piceatannol glucoside were extracted from Polygonum cuspidatum Sieb.…”