161326-34-7

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.

Fungicide.

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

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.

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.