Luteoskyrin, an Anthraquinoid Hepatotoxin, and Ascorbic Acid Generate Hydroxyl Radical in vitro in the Presence of a Trace Amount of Ferrous Iron

Abstract

Luteoskyrin is a bis-dihydroanthraquinone mycotoxin produced by Penicillium islandicum Sopp. By using EPR spin-trap techniques we investigated whether •OH is formed in a model system containing ascorbic acid and the toxin. In the presence of DMSO and DMPO, we found signals of DMPO-CH₃, a more specific and reliable signature of •OH than DMPO-OH, together with the signals of ascorbyl radical. DMPO-CH₃ signals increased with time of incubation up to 5.5 min. The DMPO-CH₃ formation depended completely on both luteoskyrin and ascorbic acid, and deferoxamine, an iron-chelator, inhibited its formation. The signals disappeared in the presence of excess amount of catalase whereas SOD showed no effect. These results suggest that •OH is formed from ferrous ion present in the mixture of H₂O₂ generated from ascorbic acid and luteoskyrin.

Key Words:

• hydroxyl radical
• DMPO-CH₃
• luteoskyrin
• ascorbic acid
• ascorbyl radical
• mycotoxin