Denatonium, usually available as denatonium benzoate (under trade names such as BITTERANT-b, BITTER+PLUS, Bitrex or Aversion) and as denatonium saccharide (under trade names such as BITTERANT-s), is the most bitter chemical compound known, with bitterness thresholds of 0.05 ppm for the benzoate and 0.01 ppm for the saccharide.It was discovered in 1958 during research on local anesthetics by MacFarlan Smith of Edinburgh, Scotland, and registered under the trademark Bitrex.