Uses
antifungal, P450 inhibitor
Uses
Triadimefon is an triazole fungicide is used for the management of mango powdery mildew in South Gujarat.
Uses
Systemic agricultural fungicide.
General Description
Colorless to pale yellow crystalline solid with a slight odor.
Air & Water Reactions
Insoluble in water.
Reactivity Profile
Triadimefon is incompatible with strong oxidizing agents and acids. Reacts with acid halides and anhydrides. Also reacts with most active hydrogen compounds .
Fire Hazard
Flash point data for Triadimefon are not available; however, Triadimefon is probably combustible.
Description
Triadimefon has been a widely used fungicide on crops and
nonfood products since the early 1970s. The metabolite triadimenol
is also active and is registered separately for use as
seed treatment. Triadimenol has a broad regulatory toxicology
database, but its toxicity is considered to be encompassed in
that of triadimefon and therefore the same study was used by
the United States Environmental Protection Agency (US EPA)
in establishing regulatory levels for both pesticides. In
nontarget species, dopaminergic neurotoxicity is the primary
effect, but with chronic exposures its toxicities include hepatic,
carcinogenic, developmental, and reproductive effects.
Definition
ChEBI: 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)butan-2-one is a member of the class of triazoles that is 1-hydroxy-3,3-dimethyl-1-(1,2,4-triazol-1-yl)butan-2-one in which the hydroxyl hydrogen is replaced by a 4-chlorophenyl group. It is a member of triazoles, a member of monochlorobenzenes, an aromatic ether, a ketone and a hemiaminal ether.
Agricultural Uses
Fungicide: Triadimefon is a systemic fungicide that is used to
control powdery mildews, rusts, and other fungi on coffee,
seed grasses, cereals, fruits, grapes, vegetables, vines,
pineapple, sugar cane, sugar beets, turf, shrubs, and trees.
Not approved for use in EU countries. Registered for
use in the U.S.
U.S. Maximum Allowable Residue Levels for Triadimefon
Trade name
ACCOST®; ACIZOL®; AMIRAL®;
BAY® 6681-F; BAYLETON®; BAY®-MEB-6447;
BAYER® 6681-F; BAYER® MEB-6447; MEB 6447®;
PRO-TEK®; ROFON®
Pharmacology
Triadimefon (36) and its alcohol analog triadimenol
(37) have been intensively investigated to determine
the influence of their enantiomeric difference on
fungicidal activity. Between stereoisomeric triadimefon,
no significant difference is observed in their fungicidal
activity. However, triadimenol, which shows a much
higher fungicidal activity than triadimefon, exhibits a clear stereochemistry-dependent activity difference.
Greater fungicidal activity is possessed by the (1S,
2R)-isomer (28).
Environmental Fate
Soil. In a culture study, the microorganism Aspergillus niger degraded 32% of tri-
adimefon to triadimenol after 5 days (Clark et al., 1978).
Plant. In soils and plants, triadimefon degrades to triadimenol (Clark et al., 1978;
Rouchaud et al., 1981). In barley plants, triadimefon was metabolized to triadimenol and
p-chlorophenol (Rouchaud et al., 1981; Rouchaud, 1982). In the grains an
Photolytic. When triadimefon was subjected to UV light for one week, p-chlorophenol,
4-chlorophenyl methyl carbamate and a 1,2,4-triazole formed as products (Clark et al.,
1978).
Metabolic pathway
Enzymic reduction of triadimefon is an important pathway in plants, soils
and fungi and may be regarded as an activation process, which produces
fungicidally active triadimenol. Two diastereoisomers of triadimenol, A
and B [( 1RS,2SR)-l-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)
butan-2-ol is referred to as diastereoisomer A; 1RS,2RS- is referred to as
diastereoisomer β], are produced in different amounts by plants and fungi
and the proportions may differ within the plant. Similar metabolic pathways
are followed in mammals where reduction of the keto group yields
triadimenol as the principal metabolite and oxidation of the butyl group
gives alcohol and carboxylic acid derivatives.
Degradation
Triadimefon is stable to hydrolysis with a DT50 of more than 1 year at pH
3,6 and 9 (22 °C).
On photolysis in methanol in borosilicate glass apparatus using a
medium pressure mercury lamp, triadimefon undergoes cleavage of the
C-1-N bond giving 1,2,4-triazole (2), 4-chlorophenyl methyl carbonate
(3) and 4-chlorophenol(4) (Clark et al., 1978) (Scheme 1).
Sensitised photolysis of triadimefon irradiated by light from a highpressure
mercury lamp, with a Pyrex filter to exclude wavelengths below
290 nm, in the presence of fulvic acid and humic acid gave a variety of
products. In water, the products formed were 4 and a dihydroxychlorobenzene
(5). Although there are some ambiguities in the report concerning
the allocation of structures to the compounds obtained, these included a dihydroxybenzaldehyde (6) and 5-chlorosalicylaldehyde (7). Major
products in the presence of fulvic acid were 4 and a dihydroxychlorobenzene
(5). In the presence of humic acid 4,5, a dihydroxybenzaldehyde
(6) and 1-phenoxy-33-dimethyl-1- ( 1H-1,2,4-triazol-l- yl) -2-butanone (8)
were formed (Moza et al., 1995).
Toxicity evaluation
Triadimefon inhibits the lanosterol demethylase, thereby
interfering with ergosterol synthesis that is necessary for the
integrity of fungal cell walls. This action confers specificity for
fungi over vertebrates; however, by a similar mechanism
triazoles have been reported to disrupt steroid and cholesterol
metabolism in mammals. Perturbations of fatty acid, steroid,
and xenobiotic metabolism pathways in liver through specific
nuclear signaling pathways (constitutive androstane receptor
(CAR) and pregnane X receptor (PXR)) have been suggested to
contribute to the observed reproductive and hepatic toxicities.
Triadimefon also both inhibits and induces specific hepatic
cytochrome P-450 enzymes. A series of studies comparing
triadimefon with other two conazoles (propiconazole and
myclobutanil) have shown different modes of action in terms
of carcinogenicity, hepatotoxicity, and developmental and
reproductive toxicities.
Studies in several species have shown that neurotoxicity is the
endpoint of concern with both acute and repeated exposures to
triadimefon and triadimenol. Triadimefon causes accumulation
of synaptic dopamine, both in vivo and in vitro. Pharmacological
challenges and neurochemical studies have shown that
triadimefon blocks dopamine reuptake by binding to the
dopamine transporter in a manner similar to other indirect
dopamine agonists, such as cocaine and d-amphetamine.
