Diplonine, a neurotoxin isolated from cultures of the fungus Stenocarpella maydis (Berk.) Sacc. that induces Diplodiosis

Abstract

Diplodiosis is a neuromycotoxicosis of cattle and sheep caused by ingestion of maize infected with the ear-rot fungus Stenocarpella (= Diplodia) maydis. Apart from ataxia, paresis, and paralysis, the toxin is responsible for stillbirths and neonatal losses characterized by the presence of spongiform degeneration in the white matter of the brain in the offspring of dams exposed to infected maize cobs. In the present study a toxin, named diplonine, which induced neurological signs in guinea pigs resembling some of those occurring in cattle and sheep, was isolated from S. maydis cultures. Purification of diplonine was achieved by methanol extraction followed by chromatographic separation on silica gel and RP-18 stationary phases. The structure and relative configuration of diplonine were defined by analysis of NMR and MS data as (S)-2-amino-2-[(1R,2S)-1-hydroxy-2-methylcyclopropyl] acetic acid or the (S)-2-amino-2-[(1S,2R)-diastereomer.