Inhibition of oxidative DNA damage in vitro by extracts of Brussels sprouts

Cruciferous vegetables have cancer preventive effects which may be due to r eduction of oxidative DNA damage. We investigated the effect of an aqueous extract of cooked Brussels sprouts on formation of 7-hydro-8-oxo-2'-deoxygu anosine (8-oxodG) in calf thymus DNA in vitro. Damage was induced by a Fent on reaction, UVC (254 nm), UVA (365 nm), sunlamp light, and methylene blue with visible light. The extract inhibited 8-oxodG formation in all systems except visible light with methylene blue. The IC50 values were 6-20 mu g/ml corresponding to th e extract of 5-20 g of Brussels sprouts distributed in a volume of 50 L. Th e protective effect in the Fenton reaction was unaffected by addition of ED TA. After HPLC separation fractions were identified with similar DNA protec tive effects. Sinigrin, a glucosinolate abundant in Brussels sprouts, co-el uted with the most effective fraction and had DNA protective effects. In co mparison with other antioxidants the patterns of effect of the extract ill the five damage systems were more similar to that of sodium azide than to t hose of dimethylsulfoxide and vitamin C. Constituents of Brussels sprouts can protect DNA by direct scavenging, e.g, hydroxyl radical and other oxidants, without prooxidant effects at concent rations potentially achievable by modest intake of the vegetable.