Analysis and Anti-Helicobacter Activity of Sulforaphane and Related Compounds Present in Broccoli (Brassica oleracea L.) Sprouts

A crude methanol extract prepared from fresh broccoli sprouts was extracted with hexane, chloroform, ethyl acetate, and butanol sequentially. Residual water fraction was obtained from the residual aqueous layer. The greatest inhibition zones (>5 cm) were noted for Helicobacter pylori strain by the chloroform extract, followed by the hexane extract (5.03 cm), the ethyl acetate extract (4.90 cm), the butanol extract (3.10 cm), and the crude methanol extract (2.80 cm), whereas the residual water fraction did not show any inhibition zone. Including sulforaphane, five sulforaphane-related compounds were positively identified in the chloroform extract, of which 5-methylsulfinylpentylnitrile was found in the greatest concentration (475.7 mg/kg of fresh sprouts), followed by sulforaphane (222.6 mg/kg) and 4-methylsulfinylbutylnitrile (63.0 mg/kg). Among 18 sulforaphane and related compounds synthesized (6 amines, 6 isothiocyanates, and 6 nitriles), 2 amines, 6 isothiocyanates, and 1 nitrile exhibited >5 cm inhibitory zones for H. pylori strain. The results indicate that broccoli sprouts can be an excellent food source for medicinal substances.