All the reactions were conducted from triplicate in a final reaction volume of 50 L. To a reaction mixture containing carboxylic acid (5 mM), AMFC (25 mM), ATP (5 mM), MnCl2 (5 mM) and MgCl2 (5 mM) in MOPS buffer (50 mM; pH 8) with 2.5 % DMSO for all substrates except compounds 5, 6 and 9: 5 % DMSO (v/v) was added 0.1 mg.mL -1 of purified enzyme. The reactions, in 96-microwell plates, were stirred at 130 rpm in a Cole-Parmer™ shaker incubator at 60 °C for 24 h. Negative control reactions in absence of enzyme or substrate were performed in parallel.