Optimal extraction solvents use for extraction of Thunbergia laurifolia Linn. Leaves and its mode of action on weed control

Abstract

Thunbergia laurifolia Lindl. leaves were extracted by various ratios (0, 25, 50, 75 and 100%) of ethanol in water as solvents for crude extraction. The highest crude extract yield was obtained by using 25% ethanol solvent with three time extractions. The inhibitory effect of each extract on seed germination and seedling growth of Amaranthus gracilis was investigated. The results indicated that the 100% ethanol extract expressed the best inhibitory effect. At concentration of 1250 ppm, the 100% ethanol extract completely inhibited seed germination of A. gracilis. The 100% ethanol extract also inhibited α-amylase activities in A. gracilis seed during seed germination. However, the extract does not show effect on seed imbibition. The inhibition of induction of α-amylase increased with increasing concentration of the 100% ethanol extract.