Isolation and phytotoxicity of an active fraction and its pure compound (gallic acid) from sun spurge ( Euphorbia helioscopia L.) against harmful weeds

摘要

An active fraction (F5) and its derived pure compound (gallic acid) were extractedfrom aerial parts of sun spurge (Euphorbia helioscopia). Gallic acid was chromatographicallyisolated and identified based on spectroscopic analysis 1H and 13C NMR. To investigate the phytotoxicityof F5 (0.1%) and gallic acid (0.001%), their effects were studied against 18 test weeds.In this study, we evaluated the alterations in germination percentage (G%) and speed (GS) aswell as seedling length (SL), fresh weight (FW) and dry weight (DW). Also, the change in totalphenolic content (TPC) and lipid peroxidation in response to treatment were measured. Ourresults showed variation in the phytotoxic effect of F5 and gallic acid depending upon weedspecies. Significant reduction of germination and seedling growth by F5 and gallic acid treatmentwas common for most of weeds and F5 was more toxic than gallic acid. All weed speciesaccumulated polyphenols as a defence system, but it was not enough to prevent plant damage(lipid peroxidation). We concluded that using weed derived phytotoxic fractions (e.g., F5) andpure compounds (e.g., gallic acid) could play an effective role for weed control instead of usingharmful chemical herbicides.