Photo of milk thistle flower
Silibinin, extracted from Milk Thistle, can help protect sun damaged skin

Milk thistle extract aids the fight against skin cancer, say researchers

16 April, 2013

Natural Heath News — Two recent studies have shown that the milk thistle extract, silibinin, kills skin cells mutated by UVA radiation and protects against damage by UVB radiation, thus providing two kinds of benefit against UV-induced skin cancer and photoageing.

“When you have a cell affected by UV radiation, you either want to repair it or kill it so that it cannot go on to cause cancer. We show that silibinin does both,” says Rajesh Agarwal, PhD, lead author of both studies and programme leader of Cancer Prevention and Control at the CU Cancer Center and professor at the Skaggs School of Pharmacy and Pharmaceutical Sciences.

Deadly to cancer cells

The first study, published in the journal Photochemistry and Photobiology worked with human skin cells subjected to UVA radiation, which makes up about 95% of the sun’s radiation that reaches Earth.

Agarwal and colleagues treated these UVA-affected cells with silibinin. With silibinin, the rate at which these damaged cells died increased dramatically.

“When you take human skin cells – keratinocytes – and treat them with silibinin, nothing happens. It’s not toxic. But when you damage these cells with UVA radiation, treatment with silibinin kills the cells,” Agarwal says, thus removing the mutated cells that can cause skin cancer and photoageing.

Specifically, the study shows that pretreatment with silibinin resulted in higher release of reactive oxygen species (ROS) within the UVA-exposed cells, leading to higher rates of cell death.

But protective to skin cells

The second study, published this month by the same authors in the journal Molecular Carcinogenesis shows a different benefit. Instead of beneficially killing cells damaged by UVA radiation, treatment with silibinin protects human skill cells from damage by UVB radiation, which makes up about 5% of the sun’s radiation reaching Earth.

In this case that protection comes from increasing cells’ expression of the protein interleukin-12, which works to quickly repair damaged cells.

“It has been 20 years of work with this compound, silibinin,” Agarwal says. “We first noticed its effectiveness in treating both skin and solid cancers, and we now have a much more complete picture of the mechanisms that allow this compound to work.”

The findings add to a body of research that could lead to, amongst other things, more effective sunscreening and skincare products as well as important cancer treatments.