Skin cancer lists among one of the dreaded skin conditions across the globe. The current projections show that at least one out of five individuals will suffer from either melanoma or non-melanoma skin cancer in the course of their lifetime. Skin cancer is brought about by various genetic and environmental factors. However, the primary agent behind this dreadful skin condition is exposure to harmful ultraviolet (UV) radiation and chemical carcinogens (1). Research has shown that extended exposure of solar UV radiation to the skin may bring about various types of skin cancer including melanoma, squamous cell carcinoma, and basal cell melanoma.
It is worth noting that ultraviolet radiation (mostly Short Wave Ultraviolet (UVB) rays) attacks the superficial epidermal layer of the skin causing sunburns, skin reddening, and more worryingly, promotes the development of skin cancer (1). Also, UV rays may also act as tumor promoters, tumor initiators or a complete carcinogen thereby damaging various cellular macromolecules such as lipids, proteins, and DNA. Damage to these macromolecules offers the perfect platform for the development of skin cancer.
Numerous topical sunscreens dubbed as the "go to products" in the fight against skin cancer are teeming in the market. However, the majority of them are just marketing hype. They will probably leave you disappointed because of their toxicity, incomplete spectral protection, and inadequate use. The million dollar question is, how can you protect yourself against skin cancer? Consumption of naturally occurring botanicals looks promising and based on recent research, they may help in the prevention of skin cancer. It therefore should not come as a surprise that botanical products have taken the market by storm. One such compound is Silymarin—an extract from milk thistle of the Daisy family.
Silymarin is a compound flavonoid extracted from the seeds and fruits of the milk thistle. Chemically, the extract constitutes three flavonoids namely silychristin, silydianin, and silyblin (the most active component of the three) (2). Pharmacological studies highlight that, what makes Silymarin unique, is its non- toxic form, even in higher dosage, therefore, it may be used as a treatment for many ailments. In regards to skin cancer, various theories have been formulated as to how Silymarin may inhibit skin cancer.
Chemo Protective Mechanism of Silymarin against Chemical Carcinogenesis
Ongoing research has shown that Silymarin has anti-tumor promotion properties. It offers significant chemo protective effects as it inhibits tumor growth, tumor multiplicity, and tumor incidence. Skin tumors have been found to be regressed by Silymarin properties thus it helps in skin cancer treatment. Tumor promoters such as phorbol esters induce oxidative stress once the skin leucocytes have been infiltrated.
Because of oxidative stress, macromolecules such as proteins, lipids, and DNA are damaged thus promoting the development of skin cancer. Silymarin comes in to inhibit the depletion of these macromolecules and enzymes in the epidermis reducing the oxidative stress that may occur therefore preventing the development of skin cancer. In a nutshell, Silymarin brings about immunomodulatory, antioxidant and anti-inflammatory effects which help in tackling skin cancer (2).
Immunomodulatory effects of Silymarin in tackling skin cancer
Ultraviolet radiation brings about adverse effects on the immune system. Experimental and clinical evidence suggests that immune factors contribute to the pathogenesis of solar induced skin cancer. Moreover, reactive oxygen intermediates and UVB radiation induced DNA photoproducts tends to damage cutaneous immunity leading to the development of cancer (2).
Exposure to ultraviolet radiation may also result in the release of cytokines, which brings about UVB induced immunosuppression, that aid in the development and growth of immunogenic UV induced skin tumors. Studies on Silymarin have so far suggested that topical treatment of Silymarin offers protection against UVB induced suppression, thus the development and growth of UV induced skin tumors.
Antioxidant effect of Silymarin in tackling skin cancer
Free radical generating agents such as ultraviolet radiation constantly attack the skin causing oxidative stress which may bring about skin carcinogenesis. Besides, the moment the skin is exposed to UVB rays, it induces infiltration of the leucocytes resulting to oxidative stress. UV radiation also depletes antioxidant enzymes in the skin, therefore promoting the development of skin cancer.
Using topical Silymarin could inhibit UV induced infiltration of leukocytes and as a result impede the development of skin cancer (3). Further, Silymarin inhibits UVB induced expression of prostaglandin metabolites and cyclo oxygenase-2, which leads to the development of tumors. The above findings show that the antioxidant nature of Silymarin offers photo protection, inhibits enzymes that lead to the free radical formation and reduces the oxidative stress that results to the development of skin cancer(4).
Anti-inflammatory Effects of Silymarin in Tackling Skin Cancer
The body has a natural immune system defensive shield against radicals such as bacteria and chemical irritants in the form of inflammation. However, inflammation has a split personality in that it can promote the development of skin cancer. Inflammatory mediators including free radicals, chemokine's, cytokines and arachidonic acid which abets tumor growth and its development. Silymarin has anti-inflammatory properties which may tackle the level of inflammation thereby inhibiting the development and growth of skin cancers (4).
What is the future of Silymarin?
The use of botanicals has taken center stage in the skin care industry, more so in matters to do with skin cancer prevention. Current research shows that they may help in preventing skin cancer that comes about due to the exposure to harmful ultraviolet rays. One such botanical product that has received considerable interest is Silymarin. Research is still ongoing as to how Silymarin may help in tackling skin cancer.
However, the current experimental observations and clinical research are showing great promise and have proven that Silymarin possesses anti-carcinogenic properties, antioxidant and anti-inflammatory properties may help tackle the dreaded skin cancer. Besides, Silymarin is believed to offer photo protection against immune suppression, non-melanoma skin cancer, DNA damage, and sunburns (all these aspects promote the development and growth of skin cancer). The currently available information shows certainty that Silymarin could prevent skin cancer induced by the harmful ultraviolet rays.