Also available in 1 mL, 1 mg, 2 mg, 10 mg, 25 mg, 50 mg, 100 mg, 500 mg and bulk. Please contact Fisher for quotes. 4-Methylhistamine hydrochloride has been shown to inhibit the activity of copper-dependent enzymes such as tyrosinase and dopamine beta-hydroxylase and has also been shown to modulate the expression of genes involved in cell cycle regulation and apoptosis. Purity 95%