Protective Effect of Rehmannia glutinosa on the UV-Induced Apoptosis in U937 Cells

Ultraviolet (UV) radiation has been shown to generate reactive oxygen species (ROS), such as singlet oxygen, superoxide radicals, hydroxyl radicals and hydrogen peroxide in a variety of cells. These ROS have the potential to damage critical cellular components such as DNA, proteins, and lipids and eventually result in physical and chemical damage to tissues that may lead to cell death. The steamed root of Rehmannia glutinosa (Saeng Jihuang, SJH) is reported to have an antioxidant activity. We investigated the effect of SJH on UV-induced apoptosis in U937 cells. Upon exposure to UV, there was a distinct difference between untreated cells and cells pre-treated with 0.5-2 mg/ml SJH for 12 hours in regard to cellular redox status and morphological change to cells. SJH pre-treated cells showed significant suppression of apoptotic features such as DNA fragmentation, damage to mitochondrial function, and modulation of apoptotic marker proteins upon exposure to UV. This study indicates that SJH may play an important role in regulating the apoptosis induced by UV presumably through scavenging of reactive oxygen species.