Evidence and potential mechanism of action of indigo naturalis and its active components in the treatment of psoriasis

Indigo naturalis is effective against psoriasis. Indigo, indirubin and tryptanthrin, the main active components of indigo naturalis, have anti-inflammatory properties. To evaluate the efficacy and safety of indigo naturalis and its active components in the treatment of psoriasis. Seven databases were searched for studies of indigo naturalis and its active components for the treatment of psoriasis. The findings demonstrated a higher response rate in the Chinese herbal medicine (CHM) formula groups than in the control group for Psoriasis Area and Severity Index 60 (PASI60) (Rate difference [RD] = 0.22, <i>p</i> &lt; .0001). Among all adverse events, only the incidence of gastrointestinal adverse reactions was higher in the CHM formula group than in the control group (RD = 0.09, <i>p</i> &lt; .0001). In preclinical <i>in vivo</i> studies, indirubin showed better performance in improving the phenotype of psoriasis-like mice compared to that in controls, including the PASI score (mean difference [MD] = −3.58, <i>p</i> &lt; .0001), epidermal thickness (MD = −29.13, <i>p</i> &lt; .0001), interleukin-(IL) 17 A mRNA expression (MD = −2.27, <i>p</i> = .0066) and IL-23 mRNA (MD = −5.36, <i>p</i> = .01). Indigo naturalis combined with conventional treatments is useful for treating psoriasis. Indigo naturalis display anti-proliferative, anti-inflammatory and anti-angiogenic effects by regulating the TAK1, JAK3/STAT3, Wnt/β-catenin, Akt/PKB, FAK and AP-1/c-Jun pathway. Indigo naturalis, a Chinese herb and its main active components, indigo, indirubin and tryptanthrin are effective in treating psoriasis.Indigo naturalis, indirubin, indigo and tryptanthrin have anti-proliferative, anti-inflammatory and anti-angiogenic effects via regulating the TAK1, JAK3/STAT3, Wnt/β-catenin, Akt/PKB, FAK and AP-1/c-Jun pathways. Indigo naturalis, a Chinese herb and its main active components, indigo, indirubin and tryptanthrin are effective in treating psoriasis. Indigo naturalis, indirubin, indigo and tryptanthrin have anti-proliferative, anti-inflammatory and anti-angiogenic effects via regulating the TAK1, JAK3/STAT3, Wnt/β-catenin, Akt/PKB, FAK and AP-1/c-Jun pathways.