Stephen Paul Gibson

Avermectins and flea control : Structure-activity relationships and the selection of selamectin for development as an endectocide for companion animals

Evaluation of a wide range of avermectin derivatives for flea activity in an in vitro feeding screen using the cat flea, Ctenocephalides felis, revealed a narrow structure-activity relationship (SAR) with activity surprisingly associated with monosaccharides and especially their C-5-oximes. We discovered commercially exploitable flea activity in a single compound, selamectin 33, which also possessed the necessary antiparasitic spectrum and margin of safety for development as a broad-spectrum companion animal endectocide.

Structure of doramectin

The structures of doramectin 1 and its close analogue, 25-cyclohexyl-avermectin B2 2, have been determined by proton and carbon NMR spectroscopy, mass spectrometry and X-ray crystallography. Modern two-dimensional techniques were used to assign the proton and carbon NMR resonances. Several signals in the close-related naturally-occurring avermectins have been re-assigned.