FENAMIDONE

Description

Fenamidone (13; RPA 407213; (S)-5-methyl-2-methylthio- 5-phenyl-3-phenylamino-3,4-dihydroimidazol-4-one) is a complex III inhibitor that does not derive from the strobilurins but rather belongs to the imidazolinone chemical class. Fenamidone is a white woolly powder, with the following characteristics: mp = 137 ?C; water solubility = 7.8 mg/L; logP = 2.8, and vp = 3.4×10?7 Pa. It was first described by Mercer et al. (39) in 1998. Only the S-enantiomer shows antifungal activity, thus offering a reduction in application rates over the racemic mixture.

The Uses of FENAMIDONE

Fungicide.

Definition

ChEBI: A member of the class of imidazolones that is 3,5-dihydroimidazol-4-one substituted at position 2 by a methylthiogroup, at position 3 by an anilino group and at position 5 by phenyl and methyl groups (the S-enantiomer). A fungicide effecti e against Oomycete diseases such as downy mildew and certain leaf spot diseases.

Hazard

Moderately toxic by ingestion and skin contact. Low toxicity by inhalation.

Toxicity evaluation

Fenamidone has an acute oral LD₅₀ > 5,000 and an acute dermal LD₅₀ > 2,000 mg/kg in rats. Fenamidone is not a skin or eye irritant, is negative in the Ames test, and is nonteratogenic. It shows low toxicity to birds in acute and dietary studies but has a 96-h fish LC50 of 0.74 mg/L.