Rubrobramide, a cytotoxic and phytotoxic metabolite from Cladobotyrum rubrobrunnescens

Cladobotrin (1) and rubrobramide (2) were isolated from the culture filtrate of Cladobotryum rubrobrunnescens, a mycophilic deuteriomycete. Rubrobramide (2), possessing a unique oxidized tricyclic system, is a new compound structurally related to flavipucine (3), which also is produced by the fungus. The structure of 2 was determined by spectroscopic methods. Cladobotrin (1) exhibited weak nematicidal activity toward Meldogyne incognita, while 2 showed weak cytotoxic and phytotoxic activities.