Polygonum thunbergii

A preliminary screening test (TLC bioassay) for benzimidazole antidotes was carried out using 22 plant species, representing 18 plant families. As shown in Table 2 (A), out of the 22 plants tested, benzimidazole antidote activity was initially found only in Polygonum thunbergii (Polygonaceae). An aliquot, equivalent to 125 mg of fresh plant material, of the EtOAc soluble constituents from methanol extracts of P. thunbergii was sufficient to clearly show the antidote activity on a thin-layer plate [Table 2 (B)]. 

T. squarrosum, T. thunbergii Persicaria hydropiper, Polygonum hydropiper Eugenia aromatica, E. caryophyllata, E. ulmoides... 

Plant materials were collected in and around Sapporo during the summer months. For the screening test, 10 g (fresh weight) of the aerial parts (mainly leaves/stems) were immersed in 150 ml of MeOH for 3-4 days at room temperature. The resulting extract was then reduced to dryness and the residue was partitioned between EtOAc and water. In order to isolate and characterize the antidotes, Polygonum lapathifolium L. subsp. nodosum, P. sachalinense Fr. Schm. and P. thunbergii were collected in large quantities and extracted with MeOH. 

---