Methyl paraben-d3 (Methyl 4-hydroxybenzoate-d3) is the deuterium labeled Methyl paraben (HY-N0349). Methyl Paraben is a standardized methyl paraben allergen isolated from Yunnan hemlock (Tsuga dumosa). Methyl Paraben is commonly used as a stable, non-volatile preservative. Methyl Paraben increases histamine release and cellular regulation of immunity, blocks sodium channels, and prevents ischemia-reperfusion injury[1][2][3][4].