N-Methyl indoxyl Esters as Substrates for Cholinesterase

Abstract

Several esters were prepared as substrates for cholinesterase: the acetate, propionate and butyrate esters of N-methyl indoxyl, umbelliferone acetate, and the acetate and butyrate esters of 4-methyl umbelliferone. Comparison of these substrates with other fluorogenic esters: indoxyl acetate, indoxyl butyrate, resorufin acetate, B-carbonaphthoxycholine, and β-naphthyl acetate indicated that N-methyl indoxyl butyrate was the best substrate for pseudo cholinesterase. Analysis of as little as 5 × 10⁻⁶ units per ml. of cholinesterase can be performed by a direct initial reaction-rate method in 2–3 minutes with an accuracy and precision of about 1.5%.