Cytotoxicity and potential antiviral evaluation of violacein produced by Chromobacterium violaceum

ABSTRACT

Natural products are an inexhaustible source of compounds with promising pharmacological activities including antiviral action. Violacein, the major pigment produced by Chromobacterium violaceum, has been shown to have antibiotic, antitumoral and anti-Trypanosoma cruzi activities. The goal of the present work was to evaluate the cytotoxicity of violacein and also its potential antiviral properties.The cytotoxicity of violacein was investigated by three methods: cell morphology evaluation by inverted light microscopy and cell viability tests using the Trypan blue dye exclusion method and the MTT assay. The cytotoxic concentration values which cause destruction in 50 percent of the monolayer cells (CC50) were different depending on the sensitivity of the method. CC50 values were > 2.07 ± 0.08 æM for FRhK-4 cells > 2.23 ± 0.11 æM for Vero cells; > 2.54 ± 0.18 æM for MA104 cells; and > 2.70 ± 0.20 æM for HEp-2 cells. Violacein showed no cytopathic inhibition of the following viruses herpes simplex virus type 1 (HSV-1) strain 29-R/acyclovir resistant, hepatitis A virus (strains HM175 and HAF-203) and adenovirus type 5 nor did it show any antiviral activity in the MTT assay. However violacein did show a weak inhibition of viral replication 1.42 ± 0.68 percent, 14.48 ± 5.06 percent and 21.47 ± 3.74 percent for HSV-1 (strain KOS); 5.96 ± 2.51 percent, 8.75 ± 3.08 percent and 17.75 ± 5.19 percent for HSV-1 (strain ATCC/VR-733); 5.13 ± 2.38 percent, 8.18 ± 1.11 percent and 8.51 ± 1.94 percent for poliovirus type 2; 8.30 ± 4.24 percent; 13.33 ± 4.66 percent and 24.27 ± 2.18 percent for simian rotavirus SA11, at 0.312, 0.625 and 1.250 mM, respectively, when measured by the MTT assay