Maltol,an antioxidant component of Korean red ginseng,shows little prooxidant activity

Some antioxidant phenolic compounds exhibit prooxidant activity mainly due to their abilities to reduce Fe¹⁺ to Fe²⁺. Reducing ability and prooxidant activity of maltol, an antioxidant component of Korean red ginseng, were compared with those of pyrogallol. Maltol at 2 mM did not appreciably reduce Fe¹⁺ to Fe²⁺ and also failed to reduce nitroblue tetrazolium. Stimulation of hydroxyl radical mediated-deoxyribose degradation by pyrogallol was maximal at 60 μM. Maltol stimulated the deoxyribose degradation to a much less extent, and a similar stimulatory effect was observed at a concentration of more than 100-fold higher than that of pyrogallol. The stimulatory effect of maltol reached a plateau over 1 mM, suggesting the removal of hydroxyl radicals by excess maltol. In bleomycin-Fe³⁺-DNA assay, maltol at 2 mM produced a 2.5-fold increase of the iron-bleomycin-dependent DNA degradation over the basal value, whereas pyrogallol at 10 μM accelerated DNA degradation by ca. 10-fold. Furthermore, maltol inhibited Fe²⁺-stimulated DNA degradation by bleomycin. These results strongly suggested that maltol is an antioxidant with little prooxidant activity.