In vitro evidences of the traditional use of Rhus coriaria L. fruits against skin inflammatory conditions.

Rhus coriaria L. (R. coriaria) is a medicinal herb native to the middle east and Mediterranean region and well-known as "sumac" or "sicilian sumac". This herb has a wide range of traditional applications, covering its topical use to treat skin burns or eczemas and to promote wound healing.The present research aims to investigate the potential anti-inflammatory activity of Rhus coriaria L. fruit extracts in human keratinocytes (HaCaT cells), evaluating extracts prepared using different techniques.Water (WRC), ethanol-water (EWRC) and two types of ethanol extracts (mERC and ERC) were prepared. The HaCaT cells were challenged by TNF-α (10 ng/mL) and IL-8, ICAM-1, VEGF, and MMP-9 release, as well as NF-κB translocation, were measured by ELISA assays. The most active extracts were chemically profiled through HPLC-UV-DAD analysis.

Althought all the extracts inhibited the TNF-α-induced IL-8 release, just mERC and EWRC suppressed NF-κB activation, ICAM-1, and MMP-9 secretion. EWRC showed higher inhibition on ICAM-1 and MMP-9 with IC₅₀s of 1.76 ± 0.24 and 1.24 ± 0.33 μg/mL, respectively (mean ± s.d.). On the contrary, mERC significantly decreased VEGF levels whereas EWRC did not show any effect. The HPLC-UV profile of the extracts revealed higher amount of anthocyanins in EWRC in comparison with mERC.

Our results suggest the potential positive effect of R. coriaria fruit extracts, mostly mERC, as preventive agent in the treatment of keratinocyte inflammation through their inhibitory effect on the production of skin pro-inflammatory mediators.