Background: Traditional Chinese medicine is effective in the treatment of psoriasis and can significantly reduce skin inflammation and psoriatic lesions with minimal side effects. Shikonin (SHI) and β,β-dimethylacryloyl alkannin (DMA), the main active components of Lithospermum erythrorhizon, have strong anti-inflammatory effects. This systematic review aimed to evaluate the efficacy and safety of Lithospermum erythrorhizon and its main active components and to elucidate the potential mechanisms of their action in psoriasis treatment.

Methods: PubMed, Embase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, Chinese Scientific Journals, Wan Fang, and Chinese Biomedicine databases were systematically searched for articles published between 1 January 1970, and 31 February 2021. We included clinical and preclinical studies that examined the effects of Lithospermum erythrorhizon and its active components on psoriasis. All data were analyzed using RevMan 5.3 software. The Cochrane and SYRCLE’s risk-of-bias tools were used to assess the quality of all studies.

Results: Eleven clinical trials including 1024 participants and 23 preclinical studies were assessed. Meta-analysis showed that when treating patients with psoriasis, the Chinese herbal medicine (CHM) formulas with Lithospermum erythrorhizon as the sovereign herb can significantly improve psoriatic dermatitis, which can significantly reduce the psoriasis area and severity index (PASI) score (mean difference [MD] = -2.00, 95% confidence interval [CI] [-3.19, -0.80], p = 0.001; I² = 85%). The incidence rates of diarrhea (risk ratio = 0.21, 95% CI [0.06, 0.81], p = 0.02) were higher in the CHM formulas group than in the control group, whereas other adverse events were not significantly different between the two groups (p > 0.05). We evaluated the PASI score of mice on day 7 and found that SHI and DMA also alleviated psoriatic lesions (MD = -3.36, 95% CI [-4.67, -2.05], p < 0.00001, I² = 94%). Furthermore, the epidermal thickness decreased more after SHI or DMA treatment than in the control group (MD = -34.42, 95%CI [-41.25, -27.59], p < 0.00001, I² = 93%). Based on preclinical studies, we also summarized and mapped the mechanisms of SHI and DMA in the treatment of psoriasis.

Conclusion: Available findings demonstrated that Lithospermum erythrorhizon combined with other conventional treatments is useful in treating psoriasis. Preclinical evidence has shown that the active components of Lithospermum erythrorhizon exhibit a potential anti-inflammatory effect, promote keratinocyte apoptosis, inhibit keratinocyte proliferation and angiogenesis, and block the cell cycle. In summary, our findings suggest that Lithospermum erythrorhizon and its active components can be used to treat psoriasis.