Metabolism of Flutolanil in Rice Plant and Cucumber

Abstract

After [aniline ring-¹⁴C(U)] flutolanil [3′-isopropoxy-2-(trifluoromethyl)benzanilide] was applied to paddy water, radioactivity in rice plants increased with time to reach the maximum concentration (93.7ppm ¹⁴C-flutolanil equivalent on the basis of dry weight) in the leaf blades within 27 days. Then, it gradually decreased until the leaf blades and the hulled rice contained 83.0 and 0.50ppm ¹⁴C-flutolanil equivalent after 81 days. The concentrations of unchanged flutolanil in the leaf blades and hulled rice were 3.14 and 0.03ppm, respectively. Five identified metabolites in rice plants were 4′-hydroxy-3′-isopropoxy-2-(trifluoromethyl)-benzanilide (2), 3′-(hydroxymethyl)ethoxy-2-(trifluoromethyl)benzanilide (3), 3′-hydroxy-2-(trifluoromethyl)benzanilide (4), 4′-hydroxy-3′-methoxy-2-(trifluoromethyl)benzanilide (6) and 3′-methoxy-2-(trifluoromethyl)benzanilide (7). In the aqueous extracts, there existed the conjugates of 2, 3, 4 and 6, among which the conjugated 4 was a major metabolite of flutolanil in rice plants. ¹⁴C-Flutolanil applied topically on the leaves of cucumber hardly penetrated into the plant so that 70% of ¹⁴C-flutolanil was recovered as the surface wash even after 13 days. Although only 10% of the applied radioactivity was found in cucumber, the metabolites similar to those in rice plants were obtained but in less amounts.