Increase of Bioactive Sulforaphane and Its Related Compounds with Sulfur Compounds in Broccoli (Brassica Oleracea Var. Italica) Sprouts During Cultivation

The effects of sulfur containing compounds on the level of biologically active sulforaphane and related compounds in broccoli sprouts were investigated. Sulforaphane and 7 related compounds were identified in the chloroform extract of broccoli sprouts grown in cultivation waters containing different concentrations of Na2SO3, Na2SO4, or NaCl. Of the 5 nitriles identified, the concentrations of 5-methylsulfinylpentylnitrile were the greatest, ranging from 2,828.2 ?g g-1 (grown in a 1.0 mM Na2SO4 cultivation water) to 825.9 ?g g-1 (2.0 mM NaCl). Of the 3 isothiocyanates (erucin, iberin, and sulforaphane) identified, the concentrations of sulforaphane were the greatest, ranging from 1,600.5 ?g g-1 (1 mM Na2SO4) to 453.7 ?g g-1 (2.0 mM NaCl), followed by iberin, which ranged from 1,001.4 ± 103.4 ?g g-1 (1.0 mM Na2SO4) to 128.7 ± 19.0 ?g g-1 (2.0 mM NaCl), and erucin, which ranged from 29.8 ± 3.7 ?g g-1 (1.0 mM Na2SO4) to 10.9 ± 7.7 ?g g-1 (2.0 mM NaCl). When fresh broccoli sprout samples were treated with myrosinase, the sulforaphane concentrations increased from 884.3 ?g g-1 to 5,403.6 ?g/g in the sprouts grown in a 1.0 mM Na2SO3 cultivation water (3.78 fold). The greatest rate of increase was observed in the case of control samples. It increased from 482.5 ?g g-1 to 1,905.7 ?g g-1 (3.95 fold). The study demonstrated that the addition of sulfur compounds to cultivation water significantly increased the amounts of sulforaphane and related compounds in broccoli sprouts. In particular, myrosinase treatment increased the level of sulforaphane in broccoli sprouts; appreciable level changes were not observed for the other compounds.