Galdieria sulphuraria Relieves Oily and Seborrheic Skin By Inhibiting the 5-α Reductase Expression in Skin Cells and Reducing Sebum Production In Vivo

The sebum has important protective functions for the skin, although its overproduction may lead to undesired aesthetic problems and even more serious skin diseases. Sebum overproduction is caused by the androgen hormone testosterone, which is regulated by the enzyme 5-α Reductase, and can be associated with an over-proliferation of parasitic microbes that cause serious infections linked to skin inflammatory reactions. From the extremophile microalga Galdieria sulphuraria, we obtained a water-soluble extract and we found that it was capable of inhibiting the enzyme 5-α Reductase, inducing the expression of the β-defensins, which represents the first defense response mechanism triggered by the skin cells to fight against undesired microbes, and stimulating the wound healing process in skin cell cultures. The microalga extract was finally employed in clinical tests on human volunteers and it was confirmed its capacity to regulate sebum production. The results suggested that the Galdieria extract had interesting potentialities as active ingredient in cosmetic and dermatological formulas, in particular in those addressed to oily and seborrheic skins.