Violacein

Violacein, an indole-derived purple-colored natural pigment produced by Janthinobacterium lividum, displays multiple biological activities, including strong inhibition of Gram-positive pathogens. It inhibits the growth of head and neck carcinoma cell lines both in vitro and in vivo. Violacein permeabilizes the cytoplasmic membrane of bacterial cells but does not affect the cell wall.