Evaluation of an improved antinematodal assay against the plant-parasitic nematode Bursaphelenchus xylophilus and its application to an antinematodal activity study of synthetic 4-methylumbelliferyl glycoside

A novel assay was developed to evaluate chemicals that exhibit antinematodal activity against mycetophagous nematodes, including the pine wilt nematode Bursaphelenchus xylophilus. This new assay was superior to the previously reported cotton ball test in terms of reproducibility and quantitativeness. In this new method, annular filter papers were used instead of cotton balls to calculate half-maximal inhibitory concentration. Morantel tartrate (MT), an antinematodal agent, was used as an indicator to confirm the efficacy of this novel assay. Results indicated that the assay procedures could be simplified without counting nematodes, and that detailed comparisons with other samples are possible. This novel assay was used to study the activity of 4-methylumbelliferone (MU) and synthetic MU glycosides. To improve the solubility of antinematodal MU in water, Mitsunobu reagent was used for glycosylation to synthesize four MU glycosides. The results of this novel assay revealed that MU had lower antinematodal activity than MT. The solubility of MU glycosides in water was improved, but their activity was reduced.