Sulforaphane (derived from its cognate glucosinolates glucoraphanin) is among the most extensively studied derivatives of isothiocyanates and the principal bioactive component in broccoli or broccoli sprouts, its molecular formula is C₆H₁₁NOS₂ and  the relative molecular weight is 177.29. In 1992, Professor Paul Talalay from Hopkins University extracted sulforaphane from broccoli and confirmed that sulforaphane was a inducer of Ⅱ phase detoxification enzymes, provided scientific evidence of broccoli anticancer. Ⅱ phase detoxification enzymes include glutathione S-transferase and quinone reductase, which can develop resistance to many carcinogens to play an anticancer role. At the same time, sulforaphane is a common antioxidant, which is the plant active substance with the best anti-cancer effect found in fruits and vegetables.

Sulforaphane exists in broccoli in the form of its precursor, glucoraphanin, which is a glucosinolate with the molecular formula C₁₂H₂₃NO₁₀S₃ and it's relative molecular weight is 437.51. The content of glucoraphanin in broccoli seeds is the most abundant, it can be converted to sulforaphane by hydrolysis of myrosinase or intestinal flora.