(Rac)-Shikonin (Anchusin) is a natural red naphthoquinone pigment, has antimicrobial, anti-tumor, and anti-inflammatory effects; a purified shikonin preparation is widely used for the production of medicinals, cosmetics, and some food products; shikonin also enters into the antiinflammatory ointment and cream compositions used for the treatment of burns. It can suppress the cell viability, adhesion, invasion and migratory ability of MGC-803 cells through TLR2- or NF-κB-mediated pathway.

At nanomolar concentrations, shikonin inhibits monocyte chemotaxis and calcium flux in response to a variety of CC chemokines (CCL2 [monocyte chemoattractant protein 1], CCL3 [macrophage inflammatory protein 1α], and CCL5 [regulated upon activation, normal T-cell expressed and secreted protein]), the CXC chemokine (CXCL12 [stromal cell-derived factor 1α]), and classic chemoattractants (formylmethionyl-leucine-phenylalanine and complement fraction C5a). Shikonin down-regulates surface expression of CCR5, a primary HIV-1 coreceptor, on macrophages. The anti-HIV and anti-inflammatory activities of shikonin may be related to its interference with chemokine receptor expression and function[1]. Shikonin inhibits enterocyte calcium-activated chloride channels, the inhibitory effect is partially through inhibition of basolateral K+ channel activity[2].

Freshly isolated human monocytes are plated in a 96-microwell plate (Costar) at 105 cells per well with shikonin at a final concentration of 10, 1, 0.1, 0.01 μM. The numbers of viable cells, as detected by MTS test and the trypan blue exclusion assay, were measured 12 and 24 h after incubation at 37°C in humidified air with 5% CO2. (Only for Reference)