Isolation and characterization of polygonum equisetiforme flavonoids and their acaricidal activity against tetranychus urticae koch

Abstract

Acaricidal activity assessment against Tetranychus urticae Koch (Acari: Tetranychidae) of different extracts of Polygonum equisetiforme (Polygonaceae) aerial parts revealed that butanol extract has the highest activity. Processing of this fraction using repeated column and thin layer chromatographic techniques resulted in the isolation of five flavonoids, which have identified NMR as; quercetin (1), avicularin (2), isoquercitrin(3), betmidin (4) and myricitrin (5). All the five isolated flavonoids showed acaricidal activity using leaf-dip technique against T. urticae Koch larvae in the following decreasing activity order; quercetin (LC50 =11.28 ppm), avicularin (46.72 ppm), isoquercitrin (63.77 ppm), myricitrin (169.66 ppm) and betmidin (188.11 ppm). While the activity against the adult females was found to be quercetin (LC50 =16.28 ppm), isoquercitrin (93.38 ppm), avicularin (98.57 ppm), betmidin (161.00 ppm) and myricitrin (206.68 ppm) after 7 days of treatment. This is the first report on isolation of the two flavonoids betmidin (4) and myricitrin (5) from P. equisetiforme.