A γ-lactone form nafuredin, nafuredin-γ, also inhibits helminth complex I

Abstract

Nafuredin, a δ-lactone antibiotic, is a fungal metabolite showing selective helminth NADH-fumarate reductase inhibition, and whose target had been revealed as complex I. We found that nafuredin is easily converted to nafuredin-γ by weak alkaline treatment. The structure of nafuredin-γ was elucidated as a γ-lactone form of nafuredin with keto-enol tautomerism. Nafuredin-γ shows similar complex I inhibitory activity as nafuredin, and it also possesses anthelmintic activity in vivo. © Japan Antibiotics Research Association.