Total phenolic content, free radical scavenging capacity, and anti-cancer activity of silymarin

Milk thistle (Silybum marianum) seeds are a good source of dietary polyphenols. The bioactive component of milk thistle seeds, silymarin, contains flavonolignans including silybin A, silybin B, isosilybin A, isosilybin B, silychristin, isosilychristin, and silydiain along with the flavonol taxifolin. Silymarin is used traditionally as a natural herbal medicine with minimal side effects. Structurally, each silymarin component possesses phenolic hydroxyl groups and thus works as an antioxidant. In addition to free radical scavenging capacities, silymarin's anti-cancer activities were reported for many different types of cancers including bladder, breast, colon, gastric, kidney, lung, oral, ovarian, prostate, and skin. The current review will discuss silymarin's chemical components, total phenolic content, free radical scavenging capacities, and anti-cancer activities.