The tetrahydroquinoline ring system is a very common structural motif and is found in numerous biologically active natural products and pharmacologically relevant therapeutic agents. variety of novel 1,2,3,4-tetrahydroquinoline-based natural products, some of which showed interesting biological activities, were reported during the 1995-2010 period. A couple of novel pyrroloquinoline alkaloids, martinellic acid 2a and martinelline 2b, was isolated from the roots of the tropical plant Martinella iquitosensis,8 and they have become synthetic. Tetrahydroquinolines having hydrogenation patterns different from the 1,2,3,4-tetrahydro-one are rarely present in natural products. Some tetrahydroquinolines are also active against antibacterial targets, including DNA gyrase and methionyl tRNA synthetase which has been proposed as an important target in the treatment of infections because of the Gram-positive bacteria resistant to conventional antibiotic therapy. Some tetrahydroquinoline derivatives have interesting activities on ion channels.