violacein

Violacein is a bacterial metabolite originally isolated from C. violaceum that has antibacterial and antiprotozoal activities.[1] [2] It is produced by C. violaceum as a purple pigment in response to N-hexanoyl homoserine lactone , a property that has been modified to create a strain of C. violaceum used in detecting quorum-sensing molecules.[3] Violacein is active against Gram-positive bacteria, including B. subtilis and S. aureus (MICs = 0.8 and 1.6 µM, respectively). It is also active against P. falciparum, including chloroquine-susceptible and -resistant strains (IC50s = 0.85 and 0.63 µM, respectively).[2] It reduces parasitemia in a mouse model of nonlethal P. chabaudi chabaudi infection when administered at a dose of 7.5 mg/kg and increases survival in a mouse model of lethal P. chabaudi chabaudi infection. Violacein permeabilizes the cytoplasmic membrane of bacterial cells but does not affect the cell wall.[1]

N-acetyltyramine is a metabolite of the biogenic amine tyramine . It enhances cytotoxicity of doxorubicin in resistant P388 murine leukemia cells with an IC50 value of 0.13 μg ml compared with an IC50 value of 0.48 μg ml for doxorubicin alone.

Aculene D, a fungal metabolite, exhibits quorum sensing (QS) inhibitory effects on Chromobacterium violaceum CV026, significantly reducing violacein production in N-hexanoyl-l-homoserine lactone (C6-HSL) induced cultures of C. violaceum CV026 at sub-inhibitory concentrations [1].