Pro-Oxidative Action of Polyphenols as Action Mechanism for their Pro-Apoptotic Activity

Author(s):

Raffaella Marina Lecci, Antonio Logrieco and Antonella Leone   Pages 1363 - 1375 ( 13 )

Abstract:

Polyphenols, secondary metabolites widely present in plant kingdom, are known for their positive effects on human health, such as treatments of degenerative disease and cancer. Many dietary polyphenols show anti-inflammatory, immunomodulatory and antioxidant properties and they are proposed as chemopreventive agents for many skin disorders and cancer. Exposure to solar UV radiation is widely considered to cause skin cancer and a consistent carcinogenic dose derived from UVA causes several skin disorders as a consequence of free radicals generation and DNA damages. </p> <p> In this study, verbascoside, isoverbascoside and tyrosol were investigated for their effects on HEKa (Human Epidermal Keratinocytes adult) cell cultures challenged from UVA-rays. Non-toxic doses of each polyphenol were assayed on HEKa before, during and after the exposure to a damaging dose of UVA. Treatment with polyphenols before and after the UVA-irradiation exerted a pro-oxidant effect, while the simultaneous treatment caused a weak decrease of ROS production. The increasing of ROS levels was associated with a proapoptotic effect on HEKa, detected by AnnexinV/Propidiun Iodide, mainly evident in surviving cells treated with the polyphenols after the UVA-irradiation. The pro-apoptotic effect was confirmed by the immunodetection of significant changes in the Bax and Bcl-x_L protein levels, leading to apoptotic events. </p> <p> The hypothesis that these polyphenols could trigger the apoptosis pathway mainly in UVA-damaged cells, via ROS increase, is here proposed as action mechanism behind their protective effect.

Keywords:

Apoptosis, HEKa, Isoverbascoside, ROS, skin cancer, Tyrosol, UV-A Verbascoside.

Affiliation:

, , National Research Council, Institute of Sciences of Food Production, (CNR, ISPA), Unit of Lecce Via Prov.le Lecce-Monteroni, 73100, Lecce, Italy.

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