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

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