RESUMEN
Nodulisporic acid A (1) is a structurally complex fungal metabolite that exhibits systemic efficacy against fleas via modulation of an invertebrate specific glutamate-gated ion channel. In order to identify a nodulisporamide suitable for monthly oral dosing in dogs, a library of 335 nodulisporamides was examined in an artificial flea feeding system for intrinsic systemic potency as well as in a mouse/bedbug assay for systemic efficacy and safety. A cohort of 66 nodulisporamides were selected for evaluation in a dog/flea model; pharmacokinetic analysis correlated plasma levels with flea efficacy. These efforts resulted in the identification of the development candidate N-tert-butyl nodulisporamide (3) as a potent and efficacious once monthly oral agent for the control of fleas and ticks on dogs and cats which was directly compared to the topical agents fipronil and imidacloprid, with favorable results obtained. Multidose studies over 3 months confirmed the in vivo ectoparasiticidal efficacy and established that 3 lacked overt mammalian toxicity. Tissue distribution studies in mice using [(14)C]-labeled 3 indicate that adipose beds serve as ligand depots, contributing to the long terminal half-lives of these compounds.
Asunto(s)
Control de Insectos , Insecticidas , Siphonaptera , Garrapatas , Tejido Adiposo/metabolismo , Administración Oral , Animales , Gatos , Perros , Femenino , Alcaloides Indólicos/síntesis química , Alcaloides Indólicos/farmacocinética , Alcaloides Indólicos/farmacología , Indoles , Insecticidas/administración & dosificación , Insecticidas/síntesis química , Masculino , Ratones , Distribución TisularRESUMEN
A series of new, diene-modified nodulisporic acid analogues (2) bearing diverse functionality at the 3"- and 4"-sites was efficiently prepared from the 3"-aldehyde 3. Biological evaluation of these synthetic nodulisporic acid analogues for systemic flea efficacy identified potent compounds and further clarified the structural requirements for ectoparasite activity.
Asunto(s)
Indoles/síntesis química , Insecticidas/síntesis química , Animales , Bovinos , Infestaciones Ectoparasitarias/tratamiento farmacológico , Indoles/química , Insecticidas/química , Siphonaptera , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
An efficient synthesis of the truncated 3"-aldehyde (3) from nodulisporic acid A (1) under mild conditions is described. Further oxidation of 3 to 3"-carboxylic acid (4) and its subsequent oxidative degradation produced 1"-aldehyde (5). These new derivatives are versatile intermediates for the preparation of new, side chain modified derivatives of nodulisporic acid A. [reaction: see text]
