Alpha pinene modulates UVA-induced oxidative stress, DNA damage and apoptosis in human skin epidermal keratinocytes.

AIMS

This study aims to evaluate the protective effect of alpha pinene (AP), an essential oil monoterpene, against ultraviolet-A (UVA; 320-400 nm) induced cellular damages in human skin epidermal keratinocytes (HaCaT cells).

MATERIALS AND METHODS

In this study, HaCaT cells were subjected to single UVA-irradiation (10 J/cm) in the presence and absence of AP (30 μM) then different cellular end points were analyzed. The protective effect of AP against UVA-induced cytotoxicity was evaluated by MTT-based metabolic assay. Generation of reactive oxygen species (ROS), alteration of mitochondrial membrane potential (MMP), DNA single- and double strand breaks (SSBs and DSBs) and apoptotic morphological changes during different treatment conditions were measured by fluorescence microscopy and spectrofluorometry. Modulatory role of AP against UVA-mediated inflammatory markers expression, nucleotide excision repair (NER) proteins and apoptotic markers expression during AP and/or UVA treatment were studied by western blot.

KEY FINDINGS

Pretreatment with AP prevented UVA-induced cytotoxicity, generation of ROS, lipid peroxidation and DNA stand breaks probably through its antioxidant property. AP also inhibited UVA-induced inflammatory mediators such as NF-κB, TNF-α and IL-6 expression in HaCaT cells. Further, AP modulates NER proteins via activation of p53 and p21 thereby subsequently prevent the formation of UVA-induced cyclobutane pyrimidine dimers (CPDs). We also noticed that AP inhibits apoptotic cell death by preventing UVA-induced loss of mitochondrial membrane potential through modulating Bax/Bcl-2 expression in HaCaT cells.

SIGNIFICANCE

The present findings suggest that AP prevent UVA-induced oxidative stress, inflammation, DNA damages and apoptosis in human skin cells.