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 μg/ml) reduced nitric oxide (NO) release and the protein expression and transcriptional activity of inducible NO synthase (iNOS). HEGU reduced prostaglandin E2 release and phospholipase A2 transcripts. HEGU reduced the secretion and mRNA levels of tumour necrosis factor-α, interleukin (IL)-6, and IL-1β. HEGU prevented IκBα degradation, p65 nuclear translocation, NFκB DNA binding and transcriptional activities. Additionally, dehydroglyasperin C, isolated from HEGU, reduced NO production, iNOS expression, and NFκB 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 NFκB signalling.