Uses
Dinobuton is a non-systemic fungicide, active against powdery
mildews in apples, cotton and vegetables.
Metabolic pathway
Dinobuton is metabolised in plants and animals via common metabolic
pathways. The primary reaction is hydrolytic cleavage of the
carbonate-dinitrophenyl linkage to yield dinoseb. Further reduction of
the nitro-groups of dinoseb yields the corresponding monoamino and
diamino analogues. Acetylation and deamination via hydroxylation/
elimination, and oxidation of the sec-butyl moiety also occurred. N- and
O-Conjugation as glucosides and glucuronides occurred in both plants
and animals. The metabolic pathways of dinobuton are presented in
Scheme 1.
Degradation
There is limited information on the hydrolytic stability of dinobuton (1).
Marchenko and Vakulenko (1983) reported that the hydrolysis DT
50 values
of dinobuton in pH 2, 7 and 11 buffer solutions at 22 °C were 15 days,
17 days and 4 hours, respectively. In vitro studies showed the rapid
hydrolysis of dinobuton to dinoseb [ 2-sec-butyl-4,6-dinitrophenol (2)] by
tissue homogenates of spider mites and animal tissues. Once generated,
dinoseb was stable to hydrolytic and photolytic degradation under acidic
condition but was readily degraded under alkaline conditions (Brestkin
et al., 1978; Molnar, 1935). Uncharacterised complex polar materials
were reported as photodecomposition products of dinoseb (Matsuo and
Casida, 1970). Grechko et al. (1986) reported that the DTW for dinobuton
in aqueous solution under UV light irradiation (365 nm) was <30 min.
