Progress in the studies on tryptanthrin, an alkaloid of history

Tryptanthrin, an indoloquinazoline alkaloid, was first obtained by sublimation of natural indigo and later isolated from the culture of fungus Candida lipolytica and a variety of other natural sources. Tryptanthrin showed a variety of intriguing biological properties such as antibacterial, antifungal, antiprotozoal, and antiparasitic activities, inhibitory activities against COX-2, 5-LOX, NO synthase and PGE(2) expression, as well as cytotoxic and antitumor activities. Present review covers recent studies on the natural sources, biological activities and mechanisms of their actions, synthesis, structure-activity relationship, and metabolism of tryptanthrin.