<i>In vitro</i> biological activities of Douglas fir essential oil in a human skin disease model

<p>Although essential oils from Douglas fir are popular topical skincare products, research regarding their biological effects on human skin cells is scarce. Here, we studied the biological activity of a commercially available Douglas fir (<i>Pseudotsuga menziesii</i>) essential oil (DEO) in a human dermal fibroblast model of chronic inflammation and fibrosis induced by stimulation with cytokines. Chemical analysis of DEO indicated that its major chemical components (i.e. >5%) were beta-pinene (23%), sabinene (17%), terpinolene (14%), delta-3-carene (11%), and alpha-pinene (9%). We analyzed the effect of DEO on the levels of 17 important protein biomarkers associated with inflammation, immune system modulation, and tissue remodeling. DEO exhibited significant anti-proliferative activity in human fibroblasts. DEO also significantly inhibited the production of vascular cell adhesion molecule 1, collagen III, and plasminogen activator inhibitor 1. We also observed that DEO robustly modulated global gene expression levels in diverse ways. In particular, DEO affected the expression of genes involved in immune modulation and cancer signaling. This study provides the first evidence of biological activity of DEO in human dermal fibroblasts. Our results suggest that DEO may modulate immune responses and tumor signaling processes. Further research about the biological and pharmacological mechanisms of DEO action is recommended.