N-Methyl-β-carboline-3-carboxamide (FG 7142): An anxiogenic agent in cigarette smoke condensate and its mechanism of formation

β-Carboline-3-carboxylic acid methylamide (FG 7142), an anxiogenic agent has been found in cigarette smoke condensate, but not in the cigarette itself. When a cigarette, except its filter portion, was immersed in 20 ml of potassium phosphate buffer, pH 7·4, then heated at 60°C for 2 days with or without presence of methylamine, FG 7142 was detected only in the mixture containing methylamine. Furthermore, when the mixtures of β-carboline derivatives and various amounts of methylamine hydrochloride were heated at 60°C for 5 days, FG 7142 was formed only in the mixtures containing methylamine and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-caroxylic acid (MTCA) or 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (TCCA). FG 7142 was also produced in the mixture of glucose, l-tryptophan and methylamine when heated at 200°C in a dry condition. These observations suggest that FG 7142 is formed through the smoking process and that methylamine in cigarette smoke may play an important role in the formation of FG 7142.