Cinnamic acid inhibits the growth of the fungus Neurospora crassa, but is eliminated as acetophenone

The effects of different benzene compounds on the growth and morphology of Neurospora crassa were investigated. No effect on colonial growth was observed with most of the compounds tested except ferulic acid and cinnamic acid (CINN). After incubation for 24 h in CINN at 200 μg ml−1 growth was reduced by approximately 94% and the branching pattern of the hyphae was altered. In liquid cultures containing CINN, the fungus started to grow after 48 h, when the concentration of this compound was 22% of that initially present. Under these conditions, acetophenone was detected in the culture filtrate, suggesting that the toxic effect of CINN on mycelial growth was reduced by N. cressa transforming it into this volatile substance, which is a starting compound in many organic reactions.