Introduction: Skin cancer is the most common type of cancer, and its incidence has gradually increased in recent years. It is characterized by aberrant cell growth with a potential to invade or spread elsewhere in the body, which involves the complex process of carcinogenesis. Ultraviolet (UV) exposure is one of the main factors inducing skin cancer, and cutaneous cells may be damaged directly by UV radiation or indirectly by UV-mediated reactive oxygen species (ROS) overproduction. However, the role of ROS in skin cancer has not been completely clarified. An elevated oxidative status has been associated with melanoma. Oxidative stress is one of the key players in skin carcinogenesis, and therefore identifying nontoxic strong antioxidants to prevent skin cancer is an important area of research. Silymarin, a plant flavonoid isolated from the seeds of milk thistle (Silybum marianum), has been shown to have chemo preventive effects against chemical carcinogenesis as well as photo carcinogenesis in various animal tumor models. The aim of this study was reviewing recent publications evaluating Silymarin as an antioxidant in Skin Cancer treatments.
Methods: In order to find relevant studies to the research question, an electronic search with time (recent five years, up to 2021) and language (English) restrictions was conducted using PubMed. Most recent studies including case control studies, original research and review articles were selected. Analysis was done and data were synthesized and compiled in a sequential and presentable paradigm.
Results: Wide range of in vivo mechanistic studies indicated that silymarin possesses antioxidant, anti-inflammatory and immunomodulatory properties which may lead to the prevention of skin cancer in in vivo animal models. both animal and cell culture studies have shown that silymarin, a naturally occurring polyphenolic flavonoid antioxidant, exhibits preventive and anticancer effects against skin cancer. For example, silymarin strongly prevents both photo carcinogenesis and skin tumor promotion in mice, in part, by scavenging free radicals and reactive oxygen species and strengthening the antioxidant system. It also has been reported silymarin has an effect by inhibiting endogenous tumor promoter tumor necrosis factor α in mouse skin, a central mediator in skin tumor promotion. Furthermore, silymarin effectively modulates cell-cycle regulators and check points toward inhibition of proliferation, and growth arrest in G0-G1 and G2-M phases of the cell cycle.
Conclusion: Thus, the available experimental information and due to its mechanism-based chemo preventive and anticancer effects in experimental models, silymarin is an important candidate for the prevention and/or therapy of skin cancer, as well as other cancers of epithelial origin in humans. Moreover, silymarin may favorably supplement sunscreen protection and provide additional anti-photocarcinogenic protection.