(DL-Nicotine-13C6) Labelled rac-Nicotine (N412420). Nicotine is an alkaloid isolated from plants. Nicotine is an active stimulant, having both addictive and carcinogenic properties. Nicotine can be absorbed through the alimentary canal, respiratory tract and intact skin. Nicotine is used in the treatment of smoking withdrawal syndrome. Nicotine has been used as an anthelmintic.