Hexane/ethanol extract of Glycyrrhiza uralensis licorice exerts potent anti-inflammatory effects in murine macrophages and in mouse skin

Previously, we prepared a hexane/ethanol extract of Glycyrrhiza uralensis (HEGU) containing undetectable amounts of glycyrrhizin, which is known to induce hypertension. This study assessed the effect of HEGU on inflammatory responses in lipopolysaccharide (LPS)-treated Raw264.7 macrophages and in mouse skin treated with 12-O-tetradecanoylphorbol-13-acetate. In the LPS-stimulated macrophages, HEGU (0-2 mu g/ml) reduced nitric oxide (NO) release and the protein expression and transcriptional activity of inducible NO synthase (iNOS). HEGU reduced prostaglandin E-2 release and phospholipase A(2) transcripts. HEGU reduced the secretion and mRNA levels of tumour necrosis factor-alpha, interleukin (IL)-6, and IL-1 beta. HEGU prevented I kappa B alpha degradation, p65 nuclear translocation, NF kappa B DNA binding and transcriptional activities. Additionally, dehydroglyasperin C, isolated from HEGU, reduced NO production, iNOS expression, and NF kappa B transcriptional activity. In the mouse inflammation model, HEGU suppressed skin swelling and iNOS and cyclooxygenase-2 expression. These results indicate that HEGU exerts powerful anti-inflammatory effects, probably mediated via the inhibition of NF kappa B signalling. (C) 2010 Elsevier Ltd. All rights reserved.