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

Life Sci. 2018 Nov 1:212:150-158. doi: 10.1016/j.lfs.2018.10.004. Epub 2018 Oct 4.


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/cm2) 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.

Keywords: Alpha Pinene; Apoptosis; DNA damage; Inflammation; Ultraviolet A radiation.

MeSH terms

  • Apoptosis / drug effects*
  • Apoptosis / radiation effects
  • Bicyclic Monoterpenes
  • Cells, Cultured
  • DNA Damage / drug effects*
  • DNA Damage / radiation effects
  • Epidermis / drug effects*
  • Epidermis / pathology
  • Epidermis / radiation effects
  • Humans
  • Keratinocytes / drug effects*
  • Keratinocytes / pathology
  • Keratinocytes / radiation effects
  • Lipid Peroxidation / drug effects
  • Lipid Peroxidation / radiation effects
  • Membrane Potential, Mitochondrial / drug effects
  • Membrane Potential, Mitochondrial / radiation effects
  • Monoterpenes / pharmacology*
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Oxidative Stress / drug effects*
  • Oxidative Stress / radiation effects
  • Skin / drug effects*
  • Skin / pathology
  • Skin / radiation effects
  • Ultraviolet Rays*


  • Bicyclic Monoterpenes
  • Monoterpenes
  • NF-kappa B
  • alpha-pinene