A New Phenol Glycoside from Root Exudates of Peperomia pellucida L. HBK. and its Role in Plant Invasion

Peperomia pellucida is an annual, shallow-rooted, succulent, delicate, glabrous herb. It is a native weed species of tropical North and South America, and it is now pantropic in distribution and abundant in India as an invasive aggressive colonizer. Medicinal properties of the plant have been well documented but no work has been done to find out the reason behind its invasive aggressive nature. The objective of our present work was to study the allelopathic activity of allelochemicals released by root exudates of P. pellucida which may play an important role in invasive and aggressive properties of the plant. Root exudates of P. pellucida were collected in root exudates trapping system. Main compound was isolated from methanol fraction of root exudates of P. pellucida, purified by thin layer and column chromatography and finally subjected to mass spectra, infrared, and nuclear magnetic resonance (both 1H and 13C) for complete structural elucidation. In vitro allelopathic activities of the compound were studied by rice, wheat and mustard seed bioassays. A new phenol glycocide [(6-(4-hydroxyphenoxy)-tetrahydro-2H-pyran-2, 3, 4, 5-tetraol); C11H14O7; Mol. Wt. 258] has been isolated and purified from root exudates of P. pellucida. This pure compound exhibited significant allelopathic activities on rice, wheat and mustard seeds in vitro bioassay experiment. This compound showed maximum inhibitory activity on rice, than in wheat and mustard bioassays. Peperomia pellucida released a phenol glycoside through root exudates into rhizophere which may act as a major allelopathic agent and may be responsible for its invasive and aggressive nature.