Abstract

Silymarin (SM) is the active component of milk thistle (MT) that is a flavonoid complex consisting of silibinin, silychristin, and silydianin. Silibinin (also known as silybin) is the major active component of the silymarin complex and is credited with giving MT its beneficial properties. Acting as a phyotonutrient silybin also provides a variety of benefits including anti-inflammatory, anti-carcinogenic and cardiovascular benefits. SM may involve suppression of NF-kappa B, a nuclear transcription factor, which regulates the expression of various genes involved in inflammation, cytoprotection, and carcinogenesis. SM blocked TNF-induced activation of NF-kappa B in a dose-and time-dependent manner. This effect was mediated through inhibition of phosphorylation and degradation of Iota kappa B alpha, an inhibitor of NF-kappa B. SM significantly reduces apoptosis, skin oedema, and depletion of catalase activity and induction of cyclooxygenase activity. This provides protection against burn-induced oxidative skin injury and photocarcinogenesis. Furthermore, SM significantly decreased skin cancer number and size in a validated model of tumor promotion. These findings are supported by other studies that show similar effects for Silibinin including protects against UV light-induced DNA damage and cancer cell growth. Moreover, silibinin enhances the powerful tumor suppressor gene p53, a genetic factor that protects against cancer. Silibinin acts by other mechanisms to prevent UV light-induced skin cancer. In fact, some findings suggest that silibinin can help to repair DNA damage caused by previous exposure to UV light.